Digitally-programmable-precision-amplifier

Thu, 21 Mar 2013 00:03:00 MST

The DG419looks into the high input impedance of the op amp, so the effects of Rvs(o"l are negligible. The DG441 is also connected in series with RIN and is not included in the feedback dividers, thus contributing negligible

50Mhz-trigger

Mon, 11 Mar 2013 00:03:00 MST

This has a stable trigger 100 m V sensitivity at 50 MHz. The FETs comprise a simple high-speed buffer and the LT1016 compares the buffer"s output to the potential at tbe trigger level potentiometer, which can be of either polarity. The 10-KO resistor provides hysteresis, eliminating "chattering"" caused by noisy input signals.

Polarity Gain Adjustment Circuit

Sun, 10 Mar 2013 00:03:00 MST

By adjusting one potentiometer, this circuit`s output can be varied from a positive-going version of the input signal, smoothly through zero output, then to a negative-going version of the input (see the figure). If the input signal is a positive pulse of, for example, +2-V peak/the output pulse amplitude can be smoothly varied from +2-V through ground (no output) to a -2-V peak. Taking a closer look at the setup, assume that the signal has a +2-V peak input. The A section of the quad op amp is an input buffer, op amp 0 provides a fixed negative-going output of -4-V peak, and op amp supplies a positive-going output that varies from +2-V to +6-V peak.

Buffer-amplifier-for-multiplexers

Thu, 07 Mar 2013 00:03:00 MST

The precision input characteristics of the HA-5147 help simplify system error budgets, while its speed and drive capabilities provide fast charging of the multiplexer"s output capacitance. This speed eliminates an increased multiplexer acquisition time, which can be induced by more limited amplifiers.

Noninverting Ac Amplifier Circuit

Thu, 28 Feb 2013 00:02:00 MST

A general-purpose noninverting ac amplifier for audio of other low-frequency applications is shown. Design equations are in the figure.

Safe-opamp-circuit

Wed, 20 Feb 2013 00:02:00 MST

In intrinsically safe applications, it is sometimes necessary to separate sections of circuitry by resistors which limit current under fault conditions. The circuit shown provides an accurate analogue output with effectively zero output impedance, despite having resistors in series with the output. which is independent of RA and RB.

Low Noise And Drift Composite Amp Circuit

Sun, 17 Feb 2013 00:02:00 MST

This circuit offers the best of both worlds. It can be combined with a low input offset voltage and drift without degrading the overall system`s dynamic performance. Compared to a standalone FET input operational amplifier, the composite amplifier circuit exhibits a 20-fold improvement in voltage offset and drift. In this circuit arrangement, A1 is a highspeed FET input op amp with a closed-loop gain of 100 (the source impedance was arbitrarily chosen to be 100 kfl). A2 is a SuperBeta bipolar input op amp. It has good dc characteristics, biFET-level input bias current, and low noise.

Cable bootstrapping

Mon, 11 Feb 2013 00:02:00 MST

Bootstrapping input shield for a follower reduces cable capacitance, leakage, and spurious voltages from cable flexing

Power Op Amp Circuit

Sat, 09 Feb 2013 00:02:00 MST

This circuit from Apex Microtcchnology can deliver 180 V p-p @ 90 kHz into a 4- load.

High Gbw Op-Amp Circuit

Wed, 30 Jan 2013 00:01:00 MST

You can build a composite amplifier featuring high gain, wide bandwidth, and good dc accuracy by cascading the sections of a dual video amplifier and adding two appropriate phase-compen-sation components.

Unity-Gain Noninverting Amplifier Circuit

Tue, 22 Jan 2013 00:01:00 MST

Biasing methods for an N-channel MOSFET to form a unity-gain noninverting amplifier

Nonlinear Operational Amplifier Circuit

Sun, 20 Jan 2013 00:01:00 MST

Using resistor and transistor feedback elements, this operational amplifier circuit can be used as a nonlinear amplifier.

Amplifier-for-signal-supply

Mon, 14 Jan 2013 00:01:00 MST

This unity-gain follower amplifier has a CMOS p-channel input, an npn second-gain stage, and a CMOS inverter output. The IC building blocks are two CA3600E"s (CMOS transistor pairs) and a CA3046 npn transistor array. A zener-regulated leg provides bias for a 400-I"A p-channel source, feeding the input stage, which is terminated in an npn current mirror. The amplifier voltage-offset is nulled with the 10-K!l balance potentiometer. The second-stage current level is established by the 20-K!lload, and is selected to approximately theiirst-stage current level, to assure similar positive and negative slew rates.

Constant-bandwidth-amplifier

Wed, 09 Jan 2013 00:01:00 MST

The traditional restnct1on of constant gainbandwidth products for a voltage amplifier can be overcome by employing feedback around a current amplifier. Two current mirrors, constructed from transistors in a CA3096AE array, effectively turn the LF351 op amp into a current amplifier. Feedback is then applied by using R2 and R1, turning the whole circuit into a feedback voltage amplifier with a noninverting gain of G of 1 + R112R2.

Op Amp Regulator

Sun, 30 Dec 2012 00:12:00 MST

This op amp offers a straightforward method of developing a single-polarity stable voltage source (see the figure). TVansi

Thermocouple-preamplifier

Fri, 28 Dec 2012 00:12:00 MST

The MAX420 is operated at a gain of 191 to convert the 52 p.VI o C output of the type J thermocouple to a 10 mV/Â°C signal. The -2.2 mV/Â°C tempco of the 2N3904 is added into the summing junction with a gain of 42.2 to provide cold-junction compensation. The ICL8069 is used to remove the offset caused by the 600-m V initial voltage of the 2N3904.

Precision-Increasing Buffer

Fri, 28 Dec 2012 00:12:00 MST

Adding an unity-gain buffer to your analog circuit can increase its precision. For example, by itself, the op a

Wide-range-digitally-controlled-variable-gain-amplifier

Sat, 22 Dec 2012 00:12:00 MST

The circuit uses the LTC1043 in a variable gain amplifier which features continuously variable gain, gain stability of 20 ppm/Â°C, and single-ended or differential inputs. The circuit uses two separate LTC1043s. LTC1043B is continuously clocked by a 1-kHz source, which could also be processor supplied. Both LTC1043s function as the sampled data equivalent of a resistor within the bandwidth set by Al"s 0.01-I"F value and the switched-capacitor equivalent feedback resistor.

Fast Composite Amplifier Circuit

Fri, 21 Dec 2012 00:12:00 MST

An ultra-low-noise, low-distortion op ampthe AD797is combined with the ADS 11 op amp, which offers a high bandwidth and a 100-mA output drive capability. The composite-amplifier circuit serves quite well when driving high resolution ADC`s and ATE systems. The fast AD811 operates at twice the gain of the AD797 so that the slower amplifier need only slew one-half of the total output swing. Using the component values shown, the circuit is capable of better than -90 dB THD with a 5-V, 500-kHz output signal. If a 100-kHz sine-wave input is used, the circuit will drive a 600- load to a level of 7 V rms with less than -109 dB THD, as well as a 10-kQ load at less than -117 dB THD.

3Input And Gate Comparator

Tue, 18 Dec 2012 00:12:00 MST

This circuit has high output only when all three inputs are high. The noninverting-input current, when all thre

Low-Offset Simple Video Buffer Circuit

Tue, 11 Dec 2012 00:12:00 MST

This circuit has proved to be an effective video buffer and will easily drive a 75- load to 1.5-V p-p output. BW is better than 20 MHz and there is less than 0.05-V dc offset, which is the difference in VBE of Ql and Q2.

Make Lm324 Op Amp Swing Rail-To-Rail

Sat, 08 Dec 2012 00:12:00 MST

By using two CMOS inverters, the output for an LM324 op amp can be increased from 3.5 Vpp to 4.9 Vpp.

Summing-amplifier

Sat, 01 Dec 2012 00:12:00 MST

This circuit uses a CA3193 BiMOS op amp. Because input noise of the amplifier is increased by Rp/ Rl//R2/ /R3, and the gain that a single input will amplify is the gain of only one of the input channels (Rp/ Rl),

Programmable-gain-differential-input-amplifier

Sat, 01 Dec 2012 00:12:00 MST

This programmable gain circuit employs a CD4051 CMOS Analog Multiplexer as a two to four line decoder,

Current-booster

Sat, 24 Nov 2012 00:11:00 MST

The LT1012 corrects de errors in the booster stage, and does not set high-frequency signals. Fast signals are fed directly to the stage via Q5 and the 0.01-uF coupling capacitors. De and low-frequency signals drive the stage via the op-amp"s output. The output stage consists of current sources, Q1 and Q2, driving the Q3-Q5 and Q4-Q7 complementary emitter follows. The diode network at the output steers drive away from the transistor bases when output current exceeds 250 mA, providing fast short-circuit protection.

Instrumentation-amplifier

Thu, 22 Nov 2012 00:11:00 MST

LTC1043 and LT1013 dual op amps are used to create a dual instrumentation amplifier using just two packages. A single DPDT section converts the differential input to a ground-referred single-ended signal at the LT1013"s input. With the input switches closed, C1 acquires the input signal. When the input switches open, C2"s switches close and C2 receives charge. Continuous clocking forces C2"s voltage to equal the difference between the circuit"s inputs.

Wideband-instrumentation-amplifier

Wed, 07 Nov 2012 00:11:00 MST

Has an input resistance of 1-MO, a bandwidth from de to about 35 MHz, and a gain of 10 times. Lowfrequency gain is provided by a CA3130 BiMOS op amp operated as a single-supply amplifier. High-frequency gain is provided by a 40673 dual-gate MOSFET.

Differential-instrumentation-amplifier

Mon, 05 Nov 2012 00:11:00 MST

This circuit relies on extremely high input impedance for effective operation. The HA-5180 with its JFET input stage, performs well as a preamplifier. The standard three amplifier configuration is used with very close matching of the resistor ratios R5/R4 and (R7 + R8)/R6, to insure high common-mode rejection (CMR). The gain is controlled through R3 and is equal to 2RI/R3. Additional gain can be had by increasing the ratios R5!R4 and (R7 + R8)!R6.

Wide-band-agc-amplifier

Wed, 24 Oct 2012 00:10:00 MST

The NE592 is connected in conjunction with a MC1496 balanced modulator to form an excellent automatic gain control system. The signal is fed to the signal input of the MC1496 and re-coupled to the NE592. Unbalancing the carrier input of the MC1496 causes the signal to pass through unattenuated. Rectifying and filtering one of the NE592 outputs produces a de signal which is proportional to the ac signal amplitude.

Noninverting-programmable-gain-amplifier

Sat, 20 Oct 2012 00:10:00 MST

This is a noninverting amplifier configuration with feedback resistors chosen to produce a gain of 0, 1, 2, 4, or 8, depending on the digital control inputs.

Buffer Amplifiers Circuit

Thu, 18 Oct 2012 00:10:00 MST

These two buffer/amplifiers that have been successfully used with VFOs: one (shown in A) is based on a pair of bipolar npn transistors,

Composite-amplifier

Mon, 15 Oct 2012 00:10:00 MST

A composite configuration greatly reduces de errors without compromising the high-speed, wideband characteristics of HA-2539. The HA-2540 could also be used, but with slightly lower speeds and bandwidth response. The HA-2539 amplifies signals above 40 kHz which are fed forward via C2; R2 and R5 set the voltage gain at -10. The slew rate of this circuit was measured at 350 V /p.s. Settling time to a 0.1 % level for a 10-V output step is under 150 ns and the gain bandwidth product is 300 MHz.

Strain-gauge-instrumentation-amplifier

Mon, 15 Oct 2012 00:10:00 MST

This circuit has an overall gain of 320. More gain can easily be obtained by lowering the value of R2. Untrimmed Vas is 10 11V. and Vas tempco is lessÂ· than O.lJIV/Â°C.

Inverting Summing Amplifier Circuit

Thu, 04 Oct 2012 00:10:00 MST

The output of Ul is the sum of Vv and multiplied by Rx/Rv RJRV and respectively. Rlj R2, R3 are selected as required for individual gains.

Photodiode-amplifier

Tue, 02 Oct 2012 00:10:00 MST

Adding two passive components to a standard photodiode amplifier reduces noise. Without the modification, the shunt capacitance of the photodiode reacting with the relatively large feedback resistor of the transimpedance (current-to-voltage) amplifier, creates excessive noise gain. The improved circuit, Fig. 3-18b, adds a second pole, formed by R3 and C2. The modifications reduce noise by a factor of 3. Because the pole is within the feedback loop, the amplifier maintains its low output impedance.

Low-input-capacitance-buffer

Tue, 02 Oct 2012 00:10:00 MST

Ql and Q2 constitute a simple, high-speed FET input buffer.Â·Ql functions as a source follower, with the Q2 current-source load setting the drain-source channel current. The LT1010 buffer provides output drive capability for cables or whatever load is required. The LTC1052 stabilizes the circuit by comparing the filtered circuit output to a similarly filtered version of the input signal. The amplified difference between these signals is used to set Q2"s bias, and hence Ql"s channel current.

Efficient Power Booster

Tue, 25 Sep 2012 00:09:00 MST

This power booster functions as a high-efficiency "power multiplexer" or, if you supply an external signal-source,

Protected Intrinsically Safe Op Amp Circuit

Mon, 10 Sep 2012 00:09:00 MST

The circuit is designed to drive an external load. A fault condition in the external load circuit could feed excessive current or voltage back into the line drive circuit. If excessive voltage appears from the load, the two zener diodes will clamp that voltage to a safe level, which in this case is 10 V.The current in the zener diodes, op amp, and the remainder of the circuitry is limited to a safe level by resistors Rl, R2, and R3. D1 protects the op-amp output stage from 10 V appearing across the clamp diodes under a fault condition.

15V-chopper-amplifier

Sun, 09 Sep 2012 00:09:00 MST

This simple circuit is a gain-of-1000 inverting amplifier. It will amplify submillivolt signals up to signal levels suitable for further processing. In almost all system applications, it is best to use as OUTPUT much gain as possible in the MAX420, thus minimizing the effects of later-stage offsets.

Programmable-amplifier

Sat, 08 Sep 2012 00:09:00 MST

Often a circuit will be called upon to perform several functions. In these situations, the variable gain configuration of this circuit could be quite useful. This programmable gain stage depends on CMOS analog switches to alter the amount of feedback, and thereby, the gain of the stage. Placement of the switching elements inside the relatively lowcurrent area of the feedback loop, minimizes the effects of bias currents and switch resistance on the calculated gain of the stage.

Current-shunt-amplifier

Tue, 04 Sep 2012 00:09:00 MST

This circuit measures the power -supply current of a circuit without really having a currentshunt resistor: R1 is only 3 em of #20 gauge copper wire. A length of the power distribution wiring can be used for Rl.

Cascaded-amplifier

Tue, 14 Aug 2012 00:08:00 MST

Cascaded amplifier sections are used to extend bandwidth and increase gain. Using two HA-2539 devices,

Ultra-precision-instrumentation-amplifier

Tue, 07 Aug 2012 00:08:00 MST

This circuit will run from a single 5 V power supply. The LTC1043 switched-capacitor instrumentation building block provides a differential-to-single-ended transition using a flying-capacitor technique. Cl alternately samples the differential input signal and charges ground referred C2 with this information. The LTC1052 measures the voltage across C2 and provides the circuit"s output. Gain is set by the ratio of the amplifier"s feedback resistors. Normally, the LTC1052"s output stage can swing within 15 mV of ground.

Inverting-programmable-gain-amplifier

Mon, 06 Aug 2012 00:08:00 MST

This circuit can be programmed for a gain of 0, -1, -2, -4, or -8. This could also be accomplished with one input resistor and one feedback resistor per channel in the conventional manner, but this would require eight resistors.

Norton-amplifier

Thu, 02 Aug 2012 00:08:00 MST

The noninverting amplifier has a gain of R2/R3 (1 in this case) and produces a voltage of V,"" during a positive excursion of Vin with respect to ground. The inverting amplifier accommodates the negative excursions of V..; its gain is given by -R6/R7, which equals -1 to maintain symmetry with the noninverti;1g amplifier. R9 provides adjustment for the symmetry, supply variations, and offsets.

Increased Feedback-Stabilized Amplifier

Mon, 16 Jul 2012 00:07:00 MST

The usual method for using a current-feedback amplifier to drive a capacitive load isolates the loa

Write-amplifier

Fri, 29 Jun 2012 00:06:00 MST

The proliferation of industrial and computerized equipment containing programmable memory has increased the need for reliable recording media. The magnetic tape medium is presently one of the most widely used methods. The primary component of any magnetic recording mechanism is the write mechanism. The concept of the write generator is very basic. The digital input causes both a change in the output amplitude, as well as a change in frequency.

Compound Op Amp Vco Driver

Thu, 28 Jun 2012 00:06:00 MST

This circuit produces 5- to 25-V output to drive a VCO from a standard Â± 15-V supply system. R7 and CI supply fr

Stabilized-amplifier

Wed, 27 Jun 2012 00:06:00 MST

This amplifier functions over a wide range of gains, typically 1-10. It combines the LT1010 and a fast discrete stage with an LT1008 based de stabilizing loop. Q1 and Q2 form a differential stage which single-ends into the LT1010. The circuit delivers 1 V pk-pk into a typical 75-0 video load. At A = 2, the gain js within 0.5 dB to 10 MHz with the - 3-dB point occurring at 16 MHz.

Differential-amplifier

Mon, 25 Jun 2012 00:06:00 MST

This differential amplifier uses a CA3193 BiMOS op amp. This classical, differential input-tosignal- ended output converter when used with lowresistance signal

Noise Blanker

Fri, 22 Jun 2012 00:06:00 MST

This noise blanker takes a sample of IF input voltage, amplifies it, and drives a switch. The switch (when activated by a noi

Single supply AC buffer amplifier

Wed, 20 Jun 2012 00:06:00 MST

The input is dc biased to mid-operating point and is ac coupled. Its input impedance is 11 - OUTPUT approximately 500K at low frequencies

Gain-Controlled Op Amp

Sun, 17 Jun 2012 00:06:00 MST

The gain controller uses a 4066 quad bilateral switch to electronically select a feedback resistor for the 741 op am

Operational-amplifiers

Sat, 09 Jun 2012 00:06:00 MST

This is a single gain-of-100 amplifier with a gain-bandwidth product of 20 MHz! The primary limitation in the performance is the low slew rate (0.3 VIJ1s) imposed by IoH charging CcoMPÂ· The effects of slew rate and compensation are shown. A lower gain amplifier requires a larger CcoMP, which in turn further reduces slew rate. For this reason, it might actually be advantageous in certain areas to lower the gain by placing a resistive divider at the input rather than raising R1.

High impedance low capacitance wideband buffer

Tue, 05 Jun 2012 00:06:00 MST

The 2N5485 has low input capacitance which makes this compound series-feedback buffer a wide-band

Bidirectional Compound Op Amp

Mon, 04 Jun 2012 00:06:00 MST

Using two transistors (Ql and Q2), a bidirectional op amp can source or sink up to 50 mA. Dl and D2 provide b

Biomedical-instrumentation-differential-amplifier

Mon, 30 Apr 2012 00:04:00 MST

This differential amplifier uses the isolated high-impedance inputs of the CA3420 BiMOS op amp.

Active-limiting-amplifier

Fri, 20 Apr 2012 00:04:00 MST

The modified inverting amplifier uses an active clamp to limit the output swing with precision. Allowance must be made for the V8E of the transistors. The swing is limited by the base-emitter breakdown of the transistors.

Oscillator Buffers

Tue, 10 Apr 2012 00:04:00 MST

CMOS buffers added to an op amp oscillator improve performance, largely as a result of nonsymmetry and variability of th

PAL powers universal ISA bus interface

Sun, 24 Mar 2013 00:03:00 MST

A pc board bearing the 16-bit ISA data-bus interface in Fig 1 can adapt automatically to either 8- or 16-bit motherboard slots. The interface comprises three bidirectional octal buffers and glue logic. The glue logic controls transfer direction and output enables.

CCD Array Reader Project

Wed, 20 Mar 2013 00:03:00 MST

The CCD Array Reader project began with a free sample of the Texas Instruments TC102-1 CCD Linear Image Sensor and its rather terse data sheet. The TC102-1 provides virtually no support circuitry, only the raw CCD (with a few special pixels) and a simple output buffer. The board shown below was designed to continously scan the TC102-1 and output a stream of digital data in parallel format. A PC computer displays the data graphically using a simple program.

Simple FIFO provides data-width conversion

Wed, 20 Mar 2013 00:03:00 MST

Many designs require FIFO elastic buffers to form a bridge between subsystems with different clock rates and access requirements. However, in some applications, you need FIFO buffers for data conversion. One example is the case in which you need to connect an 8-bit ADC to a 16-bit data-bus microprocessor through a FIFO buffer (Figure 1).

Homemade PBX

Tue, 05 Mar 2013 00:03:00 MST

This is not a low-cost design intended for publication and exact reproduction by others. It was completely tailored to what components I already had and what was cheap to buy. It is also not terribly efficient; if in doubt I insert an extra op-amp buffering stage or more clamping diodes just to be sure. The low-tech relay switching matrix is because I had tons of relays but no CMOS switches, and didn`t know how to use the latter at the time anyway. Eight telephone extensions with roughly telco spec voltages and currents (48V onhook, 90VRMS 20Hz sinusoidal ringing, about 25mA loop current offhook.) Ring trip is sub-spec but can handle at least 3 "500" type rotary dial telephone sets in parallel without false tripping. Lines are not balanced, nor is one side ground. Telco standard call progress tones (dial, busy, fast busy, audible ringing.)

Off-the-shelf ICs make 10-bit convolver

Mon, 04 Mar 2013 00:03:00 MST

LED Display controller

Wed, 27 Feb 2013 00:02:00 MST

Driving these displays takes a little work. Since they are multiplexed only one row/column can be active at a time. I found that lighting up a column at a time is best (less flicker due to only 5 columns per pass as opposed to 7 rows per pass). To get even brightness each column must be left on the same amount of time and each common anode needs a current limited connection to +5. I accomplished this by connecting the output of a 7407 open collector TTL buffer to the anode along with the current limited +5. When the buffer was on it would sink the current and the LED would not light. If the buffer was off then the current flowed through the LED and it would light up.

4-Way Intercom

Mon, 25 Feb 2013 00:02:00 MST

The Link telephone intercom is designed around two ICs. The first, IC1, is an NE 556 dual timer chip, which is wired up to provide dial tone, ring tone (busy tone too, which will be explained along with a few add-ons to be mentioned later on) and ring pulses for the ringer circuit attached to each line circuit. The other chip, IC 2, is a CD 4017B decade counter, which is wired to count each train of dial pulses as they are received and buffered by the two opto-couplers, OC1 and OC 2 and their associated R/C networks.

LED or Lamp Pulser

Thu, 21 Feb 2013 00:02:00 MST

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds.

dot-matrix LED

Mon, 18 Feb 2013 00:02:00 MST

To add tones or shades of the main colors to the tricolor LED, you do not need to modify the circuit in Figure 1; you need only consider the software. Software modifications consist of adding more color planes or pages of display buffer, adding memory locations (mapped onto the LED dots), and increasing the number of refresh times, in which the controller updates all LED dots to cover all added color planes. For example, if you decide to use four color planes, divided into two red and two green planes, for dot i of the dot-matrix LED, you`ll obtain the shades listed in Table 1.

Video amplifier

Mon, 11 Feb 2013 00:02:00 MST

Got some questions about video amps. I`ve seen an NE592 used as a video buffer amp at the end of a 75 ohm line. Used so that the 75 ohm line could drive all kinds of neat processing stuff without affecting the signal (that`s what a buffer is after all, right?) Now National Semiconductor makes an LM592 that`s also a video amp. Do these two chips cross reference to eachother?

VERY LOW POWER GATED CRYSTAL OSCILLATOR

Sun, 03 Feb 2013 00:02:00 MST

The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed. The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed. The method keeps the standby power consumption to a very low 1uA when used with a 3v supply.

Tunable IF with TDA7000

Sun, 03 Feb 2013 00:02:00 MST

This circuit has `suffered` a lot of modifications over its long life... Even the lettering on the integrated circuit was partially erased of the years. The main motive of the mods was not that the circuit didn`t work right, but were several tries to add some kind of frequency indicator to the receiver. The left RCA plug and associated components are witnesses to the last version, adding a FET buffer amplifiera and taking signal from the oscillator coil.

4-transistor H-bridge

Sat, 02 Feb 2013 00:02:00 MST

When I first started tinkering with this circuit, I made the assumption that the inverters pictured in Steve`s diagram were not intrinsic parts of the bridge, but instead were examples of the outputs coming from the "driving" circuit. This is very, very wrong. If you don`t include inverters (or, at least buffers) on the control inputs, you now have to take great care to avoid having the bridge influence the circuit that`s driving it.

PC controls inexpensive waveform generator

Wed, 23 Jan 2013 00:01:00 MST

The circuit in Figure 1 is a simple cost-effective waveform generator using PC control. You calculate the digital image of the desired waveform and store it in the 32k X 8-bit RAM (62256) through the 74HCT245 data buffer and the 16-bit local-address bus generator built with the 74LS393 binary counters. The 74LS244, acting like a selection switch, selects the clock input of the binary counter.

The "BEAM Stepper" drive circuit

Mon, 21 Jan 2013 00:01:00 MST

The 74AC240 stepper driver works by alternately enabling each half of the buffer. Only one half can be enabled at a time. Let`s assume that the top half of the driver is enabled. U1A & U1B along with R8, C1, and the input protection resistor R7 form a square wave oscillator. The outputs of U1A & U1B directly drive one coil of a bipolar stepper motor.

Active SubWoofer

Sat, 19 Jan 2013 00:01:00 MST

The controller is quite (actually very) simple. An input buffer ensures that the input impedance of the source does not affect the integrator performance, and allows summing of left and right channels without any crosstalk. The output provides a phase reversal switch, so that the sub can be properly phased to the rest of the system. If the mid-bass disappears as you advance the level control, then the phase is wrong, so just switch to the opposite position.

Accelerometer Scale Factor and Offset Adjustments

Thu, 17 Jan 2013 00:01:00 MST

The ADXL50 and ADXL05 accelerometers are small, low cost, easy to use devices. These modern integrated circuits have an onboard buffer amplifier that allows the user to change the output scale factor and 0 g bias level.

PC monitors two-way RS-232 transmission

Mon, 14 Jan 2013 00:01:00 MST

The method in Figure 1a needs no access or knowledge of the communicating devices. A C program opens two COM ports and installs interrupt-service routines for IRQ4 and IRQ3. Upon the reception of an interrupt, the routine stores a byte in a common circular buffer with the COM identifier and error flags. The main program displays the contents of the buffer, indicating time intervals in milliseconds between consecutive transfers. Although the program simplifies the time measurement, it preserves the original byte order and correctly reflects time relationships as long as the main program keeps up with transmission speed.

STK200/STK300 ISP Header

Sun, 06 Jan 2013 00:01:00 MST

If you`ve got a friend`s STK200/STK300 ISP cable, here is the signal designation needed to be tied to AVR chips. If you don`t have it, let build the buffer cable that compatible with STK200/STK300 and try also a free download "ATMEL AVR ISP" from ATMEL website.

Off-the-shelf ICs make 10-bit convolver

Tue, 01 Jan 2013 00:01:00 MST

The block diagram in Figure 1 shows how you can implement a 333 10-bit kernel using two dual FIR-filter and two delay-buffer ICs. This configuration operates with clock speeds of 32 MHz. With the appropriate modifications, the technique is also applicable to convolutions that require greater than 10-bit resolution. The block diagram implements the 333 convolution as the sum of three row vectors` dot products. FIR 1A and 1B implement the top two row vector dot products, and dual FIR 2B implements the bottom row vector dot product. FIR 2A provides a path for summing the three dot products to obtain the convolution sum.

Zero-power A/D converter uses printer port

Tue, 25 Dec 2012 00:12:00 MST

You can use a desktop or laptop PC to monitor physical variables such as temperature or pressure. A convenient way to do this is to connect an A/D converter through the ubiquitous Centronics printer port (Fig 1). The current requirement of the ADC0804LCN used here is less than 1.5 mA at 5V supply voltage with a 640-kHz clock. Tristate-buffer 74HC244 multiplexes 8 bits of A/D-converter data through 4 bits (54 through 57) of the status port of the printer adapter.

40 Meter CW/DSB Transceiver

Mon, 24 Dec 2012 00:12:00 MST

It uses 22 each 2N2222`s and will run from 12 Volts. The Receiver is a direct-conversion design with a switchable input attenuator and RF preamp, diode balanced mixer (diodes were allowed), a switchable low-pass-band-pass passive filter, and audio amplifier. (I may replace the audio final with the version presented by K8IQY, which I like much better). The Local Oscillator also serves as the VFO during transmit. The oscillator is a Colpitts design with varactor tuning, and two-stage buffer. Tuning is provided by two front-panel pots, Main and Bandspread, and an offset is provided during transmit.

Hot Swap and Buffer I2C Buses

Wed, 19 Dec 2012 00:12:00 MST

As server systems have grown, the number and complexity of input/output (I/O) cards that contain control circuitry to monitor the servers have grown in proportion.

An 89C2051 CPU 8 driver outputs

Sat, 08 Dec 2012 00:12:00 MST

This document describes the HSETI PCB. This PCB is a small simple application for the Atmel AT89C2051 microprocessor - a 20 pin 8051 variant, with FLASH (reprogrammable) program memory. The board has just two chips on it, the CPU and a driver/buffer.

Differential amp drives high-speed ADC

Sat, 08 Dec 2012 00:12:00 MST

The schematic in Figure 1 is the discrete-element version of an A/D-converter drive circuit. The circuit converts a single-ended input to a differential output. The ADC`s reference voltage determines the common-mode range of the differential outputs. The circuit contains two AD9631 amplifiersone connected in noninverting mode, and the other connected in inverting mode. The OP279 amplifiers buffer and scale the ADC`s reference voltage to set the common-mode range of the two outputs.

NE555 Basic Monostable

Sat, 08 Dec 2012 00:12:00 MST

Here the popular 555 timing IC, is wired as a monostable. The timing period is precise and equivalent to:- 1.1 x R1 x C1 With component values shown this works out at approximately 1.1msec.The output duration is independant of the input trigger pulse, and the output from the 555 is buffered and can directly interface to CMOS or TTL IC`s, providing that the supply voltages match that of the logic family.

Guitar Tremolo Unit

Tue, 27 Nov 2012 00:11:00 MST

The unit is simple to build, and does not need really low noise opamps, since they only act as a modulator oscillator. I used 1458 dual types in the prototype, and they are more than good enough. The transistors can be any low noise NPN type, and they are simply buffers, ensuring a high input impedance and low output impedance. If the unit is to built into an amplifier, it may well be possible to leave out the input transistor, since a low impedance drive circuit is probably already available from an existing opamp. It may also be possible to leave out the second transistor if a high impedance input is available at the insertion point. This is somewhat unlikely, since the most common place to have the modulator is before the tone controls.

74*245-based motor driver

Mon, 12 Nov 2012 00:11:00 MST

A simple, time-honored approach is to use one or more 74*245 chips (normally the 74AC245 is used for maximum current capability) to provide motor drive current. Here, each channel of drive power is provided by one or more buffer on the chip.

Modular Class A Buffer preamplifier

Sun, 11 Nov 2012 00:11:00 MST

A unit which is often very useful, if we need to isolate, in sound circuits, two stage between them. Then we can use this circuit which has an amplified unit, which gain X1, we do not use total negative feedback, only local, with the result that distortion remains at a very low level. Matching must be done with great care to the types of transistors, resistor between them. There must also be thermal union between the transistors, as well as the diodes LED D1-2 with the transistor Q5 and Q2 respectively.

Parametric MID Frequence EQ

Fri, 09 Nov 2012 00:11:00 MST

The circuit constitutes a natural extension of Mic-Line balance unit, but can be adapted to any other audio circuit. It is made up of two units in the series : A) A classic unit bass/ Treble and B) a parametric unit of mid frequencies. Both units can also be used autonomously or each one separately, with the required buffer unit, from previous and subsequent circuits. With the R2 we requlate the High frequencies +/- 18 db/oct at 20 KHZ, with R5 the Low frequencies +/- 18bd/oct at 20 KHZ, with R11 the Mid freq. +/- 15 db/oct and with R10 the center of mid freq. at 200 HZ - 6 KHZ band.

PC serial port buffer

Fri, 09 Nov 2012 00:11:00 MST

The circuit is a simple buffer which adds more driving capacity to PC serial port for the signal to go succesfully from PC computer to terminal server (other direction had no problems). The computer is connected to connector CON1 and the buffered output is available ar CON2. With this circuit the speed of RS232 connection to termial server could be succesfully raised for 9600 bps to 38400 bps.

2N2222 40 Meter CW/DSB Transceiver

Tue, 06 Nov 2012 00:11:00 MST

My version is a 40 Meter CW/DSB (Double-Side-Band) Transeciver. It uses 22 each 2N2222`s and will run from 12 Volts. The Receiver is a direct-conversion design with a switchable input attenuator and RF preamp, diode balanced mixer (diodes were allowed), a switchable low-pass-band-pass passive filter, and audio amplifier. (I may replace the audio final with the version presented by K8IQY, which I like much better). The Local Oscillator also serves as the VFO during transmit. The oscillator is a Colpitts design with varactor tuning, and two-stage buffer. Tuning is provided by two front-panel pots, Main and Bandspread, and an offset is provided during transmit.

Short-circuit finder uses few parts

Tue, 30 Oct 2012 00:10:00 MST

The simple tester in Figure 1 detects short circuits on assembled pc boards and also rings out cables and harnesses. The short finder has a narrow zone of threshold uncertainty and very low "insertion" voltage and current, and it`s not confused by capacitors. The circuit uses an LM10, an IC that combines a precision 200-mV reference, a reference buffer, and an independent, high-quality op amp. It can operate from supply voltages of 1.1 to 40V.

Serial MIDI Interface

Sat, 27 Oct 2012 00:10:00 MST

This page describes how to build this full-bandwidth single-port (one input and one output) MIDI interface. The interface is buffered (that is, if the PC gets behind you won`t lose data) and it works in Windows 3.1 and Windows 95 using a special (and very well-behaved) device driver. A simpler version, using an Atmel AT89C2051 microprocessor, is described here.

The "BEAM Stepper" drive circuit

Tue, 23 Oct 2012 00:10:00 MST

Baxendall Tone Control

Sun, 21 Oct 2012 00:10:00 MST

Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10KHz and 50Hz. As the controls are passive, the first transistor, Q1, is configured as common - collector to act as a buffer stage. The last transistor, Q2, provides a slight boost. Note that the gain of the output of the Baxendall circuit is less than one because of passive nature of it. The output is designed to feed an amplifier with input impedance of 10kohms to 250kohms.

7 by 10 LED Moving Sign

Fri, 19 Oct 2012 00:10:00 MST

This sign I designed uses no microprocessor. It has an eprom and multiple counters. As in most electric signs, the LEDs are matrixed, and strobed very quickly to make it possible for all 70 LEDs to appear lit. This sign is strobed horizontally, unlike most large signs which are strobed vertically. I did it this way because electrically it was simpler. The eprom has 8 outputs, of which I used 7 of them to drive the 7 horizontal rows. The eprom outputs are not strong, so they are buffered. The 10 vertical columns are activated in sequence, giving a 1/10 duty cycle. I used the 8th output of the eprom to drive the reset for all the counters, so the circuit loops when empty memory is reached, allowing for short or long messages. With a 27C512 eprom(64k bytes), messages and animations can be almost a minute long!

Ping-Pong Buffering

Tue, 16 Oct 2012 00:10:00 MST

This Application Note describes the two-endpoint case, using endpoints EP1 (TXFIFO-1) and EP3 (TXFIFO-2) for transmitting, and EP2 (RXFIFO-1) and EP4 (RXFIFO-2) for receiving data to/from the host. For simplicity, the packet data size is the same as the FIFO length (64 bytes each).

Feedback circuit eliminates CCD-driver delay mismatch

Sat, 06 Oct 2012 00:10:00 MST

In a CCD (charge-coupled device), packets of charges shift across the array. The transistor array, also called a bucket-brigade shift register, receives drive from a dual-phase clock signal. Dual-phase clock signals comprise two synchronized clock signals that are 180° out of phase. High peak-output-current CCD drivers can buffer the logic-level clock signals and turn them into high-voltage and high-peak-current signals to drive the heavily capacitive gates of the many CCD transistors.

Serial Cable for Casio Digital Cameras

Sat, 06 Oct 2012 00:10:00 MST

I built this cable for my Casio QV-200 digital camera, it should work for many Casio models. It`s basically a inverting buffer/converter to/from RS-232 voltage levels from/to CMOS levels. Why Casio didn`t put this inside the camera like everyone else does is beyond me. I built the circuit inside the hood of the DB9F connector.

MICROPOWER C-MOS OSCILLATOR

Thu, 04 Oct 2012 00:10:00 MST

If truly low power oscillators interest you, this circuit draws a mere 2 microwatts (500nA) from a 6v battery. It uses a very inexpensive C-MOS IC to produce a frequency of 2Hz. However, by changing the component values you can push it to 300Hz. The circuit draws much less current than traditional C-MOS oscillators using a Schmitt trigger inverter. It also produces fast leading edges. However, if you need more drive current, a C-MOS buffer should be included.

Serial Cable for Casio Digital Cameras

Tue, 25 Sep 2012 00:09:00 MST

7 by 10 LED Moving Sign

Tue, 18 Sep 2012 00:09:00 MST

Buffer amplifier and LED improve PWM power

Thu, 06 Sep 2012 00:09:00 MST

Figure 2 shows another approach that requires additional components but delivers the full magnitude of the voltage ramp to Pin 3 of IC1 and provides the approximately 1V-dc offset that Reference 1 requires. Transistors Q1 and Q2, resistors R1 and R2, and LED D3 form an emitter-follower amplifier for the ramp voltage available at IC1, Pin 7 across timing capacitor C1. This arrangement provides reliable current-mode operation over the full range from no-load to full-load output current by delivering a sawtooth drive with a dc offset to IC1`s ramp input. Diode D3, a yellow LED, performs a 1.7V level translation without introducing any substantial signal loss. The component values not shown depend on the application.

Balanced Microphone Preamp

Mon, 03 Sep 2012 00:09:00 MST

The circuit is differential in and out and therefore requires a balanced to unbalanced buffer to give suitable output for the next signal stages of a channel in a mixing desk. This is provided by a high performance op-amp differential gain stage, which can be a TL071 or similar IC of your choice. The stage has a gain of six or 15 dB and that sets the maximum input level at about 1.5 volts rms before clipping. This equals an SPL of over 150dB with a typical microphone!

MICRO POWER GATED CRYSTAL OSCILLATOR

Fri, 31 Aug 2012 00:08:00 MST

18-MHz oscillator with automatic level control

Thu, 30 Aug 2012 00:08:00 MST

A recent Design Idea described a method for designing simple, high-frequency LC oscillators with few passive components (Reference 1). However, for best results, practical hardware design of a stable oscillator requires more parts and greater complexity. Figure 1 shows a stable, 18-MHz oscillator with automatically leveled output amplitude control and an output buffer that delivers a sine wave with low harmonic content (Reference 2).

Inexpensive peak detector requires few components

Wed, 29 Aug 2012 00:08:00 MST

Requiring no rectifier diodes, the positive peak-detector circuits in figures 1 and 2 exploit the open-drain output of a Texas Instruments TLC372 fast comparator, IC1. Both versions of the detector are simple and inexpensive and provide a buffered, low-impedance output at VOUT. In addition, the TLC372`s high typical input impedance of 1012 eliminates any need for an input buffer stage. As Figure 1 shows, the detector`s output voltage at the output of op amp IC2A applies a feedback signal for the comparator and acts as a reference level for comparison with the input signal`s amplitude. Upon first application of input signal VIN, the voltage on the hold capacitor, C1, is 0V, and VOUT is also 0V.

PC serial port buffer

Mon, 27 Aug 2012 00:08:00 MST

The circuit is basically a two transistor buffer consistong of transistors Q1 and Q2 which can drive up to 1A current pulses, but the maximum putput current of the circuit is limited by resistor R2. Value R2 was experimentally selected by testing resistor values in range of 22 ohm to 270 ohm and value 140 ohm gave best results (it provides quite good impedance matching to cable used). It is a good idea to use at least 1W resistor in place of R2 to make sure that it does not overheat in output short circuit situation (RS232 devices must withstand that to meet the standard).

Inverters form three-phase VCO

Mon, 27 Aug 2012 00:08:00 MST

The inspiration for the VCO in Figure 1 came from Texas Instruments application notes of years ago, detailing the use of unbuffered U-type inverters for use in ring oscillators. The application notes circuit consists of only the inverters. The circuit generates relatively squarish waveforms. Any ring oscillators operation depends on the fact that an odd number of inversions exists around the loop.

Balanced Microphone Preamp

Wed, 15 Aug 2012 00:08:00 MST

The design consists of differential compound pairs of transistors with a common mode (floating) gain control connecting the emitters of the pair. The compound pairs of 2N4403 and BC549s are far more linear than any single transistor. The circuit is differential in and out and therefore requires a balanced to unbalanced buffer to give suitable output for the next signal stages of a channel in a mixing desk. This is provided by a high performance op-amp differential gain stage, which can be a TL071 or similar IC of your choice. The stage has a gain of six or 15 dB and that sets the maximum input level at about 1.5 volts rms before clipping. This equals an SPL of over 150dB with a typical microphone!

Limiting amplifier makes efficient A/D-converter driver

Sun, 12 Aug 2012 00:08:00 MST

Limiting amplifiers are useful for protecting circuitry that has a limited input range. A classic example is an input buffer for an A/D converter. Many A/D converters are susceptible to damage if the input significantly exceeds the specified range. In addition to providing the necessary input-voltage clamping, a limiting amplifier can provide the peak currents required to charge the A/D converter`s input capacitance and remain stable with step changes in input voltage.

Stepper Motor Driver

Thu, 09 Aug 2012 00:08:00 MST

Figure 7 shows all that is necessary to use the FMMT619 in a printers steppermotor driver. Running from a switched 24V-12V supply, the 4-phase motor takes a peak current of around 0.8A. With just 10mA base drive from a CMOS logic buffer the FMMT619 gives a saturation voltage of only 100mV.

7-Segment & Keypad

Mon, 06 Aug 2012 00:08:00 MST

Since the output buffer of P1 can sink 20mA (each output pin, but maximum IOL for all outputs was limited at 80mA), thus we can use P1 to drive LED display directly. As shown in the circuit, Two common-anode 7-segment LEDs are connected to P1 with 180 Ohms current limiting resistor. Each segment of two LED are tied in parallel to P1. Q1 and Q2 are activated by logic low of P3.0 and P3.1, sourcing +5V to common anode pins. P3.4 read logic low if either S1 or S2 was pressed while scanning period have made.

VERY LOW POWER GATED CRYSTAL OSCILLATOR

Mon, 23 Jul 2012 00:07:00 MST

Multiplexers convert FIFO buffer to bidirectional

Sat, 21 Jul 2012 00:07:00 MST

The circuit converts a 32k½§16 SuperSync FIFO design to bidirectional (half-duplex) using QuickSwitch QS3390 16-to-8 multiplexer/demultiplexer ICs. This implementation has the following advantages over the traditional tristate-multiplex/demultiplex approach:

5 band graphic equalizer using a single IC/chip

Sun, 15 Jul 2012 00:07:00 MST

This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems.The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low distortion, low noise, and wide dynamic range, and is an ideal choice for Hi-Fi stereo applica-tions. It also has a wide operating voltage range (3.5V to 16V), which means that it can be adapted for use with most types of stereo equipment.

7 by 10 LED Moving Sign

Sun, 15 Jul 2012 00:07:00 MST

IC forms differential line driver/receiver

Sat, 14 Jul 2012 00:07:00 MST

You can use the HFA1212 dual video buffer to implement differential line drivers and receivers (Fig 1) with a minimum of external components. Common-mode rejection is a function of the internal matched thin-film resistors, which you can pin-strap to set the required loop gains. VIN terminates in 75½º and drives both amplifiers in IC1. IC1A and IC1B have gains of -1 and +1, respectively.

Microphone uses phantom power

Sat, 14 Jul 2012 00:07:00 MST

Phantom-powered microphones derive power for their active circuitry from the receiving-end circuit through the same leads that transmit the audio signal. The output of a phantom-powered microphone is a low-impedance differential signal. IC1 is a simple voltage buffer that provides low-impedance drive for one output.

Guitar Reverb Pedal project

Fri, 13 Jul 2012 00:07:00 MST

This circuit was inspired by a friend who wanted a reberb for his portable guitar amplifier. I originally tried using NE5532 low noise op-amps for the buffer stages but they were too noisy for the low level circuits so I switched to discrete 2N3904 transistors, they seem to be fairly quiet. This circuit has a nice feature not found in most reverbs, a drive control for the spring amp. The drive can be turned way up and a nice smooth distortion effect will come out of the spring. The circuit will run on a 9V battery but will probably run it down fairly quickly, it draws about 30ma idle and around 100ma with a full signal going through.

7 by 10 LED Moving Sign

Mon, 09 Jul 2012 00:07:00 MST

Video amplifier

Mon, 09 Jul 2012 00:07:00 MST

Anyway, here`s a simple discrete video output stage. Can`t get much simpler than this. Note that there`s a serial matching resistor on the output, so you`ll have to feed 2Vp-p video into the buffer to get the usual 1Vp-p into the equipment you`re driving. This is the way it`s usually done. Sorry for the crude transistors, but I hate doing ASCII graphics.

Low Voltage Preamplifier

Sun, 24 Jun 2012 00:06:00 MST

This is a special low voltage version of my audio preamp. T1`s emitter voltage is biased close to half supply voltage (1.5V) to allow for maximum output voltage swing. Both transistors are direct coupled and have closed loop feedback to aid temperature stability. T2 realizes the amplifiers full voltage gain, and for low noise operation, T2 collector current is about 70uA. T1 merely buffers T2 and operates in emitter follower mode providing a good low output impedance. The overall S/N ratio measured at the output is shown below:

Cheap 40KHz clock

Sat, 16 Jun 2012 00:06:00 MST

This circuit has worked for me in many applications. (it might be an idea to buffer the signal befor using it. (There are still 5 unused gates in the `C14.. :-)

A Buffered Headphone Driver

Mon, 11 Jun 2012 00:06:00 MST

I started this project after reading an article in Stereophile magazine called "Aunt Corey`s Buffered Passive Preamplifier" by Cory Greenberg (Stereophile, November 1991, pg. 91). My version can be both a great headphone driver and preamp. The 4 ohm output of the buffers will drive headphones without reaching their maximum output current. The idea with buffers is that with unity gain you should be minimizing any distortion added to your signal. And trust me, the idea works.

1.5 Volt LED Flasher Circuits

Mon, 04 Jun 2012 00:06:00 MST

The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 ohm resistor while the buffer output is at +1.5 volts. When the buffer output switches to ground (zero volts) the charged capacitor is placed in series with the LED and the battery which supplies enough voltage to illuminate the LED. The LED current is approximately 3 mA, so a high brightness LED is recommended.

Instrumental Graphic Equaliser

Mon, 28 May 2012 00:05:00 MST

The input circuit is completely conventional, and uses 1/2 of a dual opamp as the initial gain stage. This is followed by the volume control, second gain stage and buffer. The output of the buffer is fed to the inputs of the filter stages, each of which has a slider for its specific frequency. The outputs of the sliders are summed using another opamp, and a distortion effect is included in the final output stage. This can be left out altogether if distortion is not desired. If used for guitar, the frequencies needed only have to range from 80Hz to about 7kHz, but to make the unit more versatile I suggest that the lowest frequency should be 31Hz, and the highest around 12kHz. This can be extended if you want.

Audio Tone Control

Sun, 27 May 2012 00:05:00 MST

Based on the classic Baxendall tone control circuit, this provides a maximum cut and boost of around 10dB at 10K and 50Hz. The first BC109C transistor (left hand side) is acting as a buffer. It provides the circuit with a high input impedance, around 250k has a voltage gain of slightly less than unity.

LED Audio Power Indicator

Wed, 16 May 2012 00:05:00 MST

This circuit is intended to indicate the power output level of any audio amplifier. It is simple, portable, and displays three power levels that can be set to any desired value. IC1A is the input buffer, feeding 3 voltage comparators and LEDs drivers by means of a variable dc voltage obtained by R5 and C4 smoothing action. The simplest way to connect this circuit to the amplifier output is to use a twisted pair cable terminated with two insulated crocodile clips.

Transistor Voltage buffer Follower

Sun, 13 May 2012 00:05:00 MST

Two examples of the most common types of Voltage followers (buffers). You can find some theory behind them in our amplifier gain and buffer amplifier pages.his first circuit is a very simple one transistor voltage follower. Consist of two biasing resistors, and one other resistor at the emitter to acquire the output voltage from. The first to resistors connected to the transistor's base are forming a voltage divider, in order to set a biasing point for the transistor to work in our desired range. Then the transistor, our gain component for the circuit which in this case is only used as a gateway to isolate two circuit stages.

High Q Notch Filter

Sat, 05 May 2012 00:05:00 MST

The twin ``T`` network is one of the few RC filter networks capable of providing an infinitely deep notch. By combining the twin `T`` with an LM102 voltage follower, the usual drawbacks of the network are overcome. The Q is raised from the usual 0.3 to something greater than 50. Further, the voltage follower acts as a buffer, providing a low output resistance; and the high input resistance of the LM102 makes it possible to use large resistance values in the ``T`` so that only small capacitors are required, even at low frequencies.

CMOS Logic Inverter Amplifier

Fri, 04 May 2012 00:05:00 MST

This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers.

Simple FIFO provides data-width conversion

Wed, 25 Apr 2012 00:04:00 MST

Interfacing PECL to LVDS

Mon, 16 Apr 2012 00:04:00 MST

This application note illustrates the simple resistor network required for interfacing a PECL driver and an LVDS receiver. Both PECL and LVDS buffers implement differential low-voltage signaling techniques, but with different swing and offset voltage levels. A PECL driver`s differential output signal is more positive than is expected by the input circuit of an LVDS receiver. Implementing pulldown resistors in a Thevenin parallel termination resistor divider network will properly bias the PECL DC voltage level to within range of the LVDS receiver.

Deglitching Techniques for High-Voltage R-2R DACs

Tue, 10 Apr 2012 00:04:00 MST

In an R-2R DAC design with supply voltages exceeding ±5V, large voltage glitches (up to 1.5V) can occur during the DAC`s major-carry transitions. These glitches can propagate through the output buffer amplifier and appear at output. The slewing of the level shifters that control the top (VREF+) and bottom (VREF-) single-pole double-throw switches (S0 to SN) causes the glitches (Figure 1).

Low Voltage Preamplifier

Fri, 06 Apr 2012 00:04:00 MST

This is a special low voltage version of my audio preamp. T1`s emitter voltage is biased close to half supply voltage (1.5V) to allow for maximum output voltage swing. Both transistors are direct coupled and have closed loop feedback to aid temperature stability. T2 realises the amplifiers full voltage gain, and for low noise operation, T2 collector current is about 70uA. T1 merely buffers T2 and operates in emitter follower mode providing a good low output impedance.

eSyndiCat Directory v2.3.05

Stabilized-capacitance-buffer

Digitally-programmable-precision-amplifier

50Mhz-trigger

Polarity Gain Adjustment Circuit

Buffer-amplifier-for-multiplexers

Noninverting Ac Amplifier Circuit

Safe-opamp-circuit

Low Noise And Drift Composite Amp Circuit

Cable bootstrapping

Power Op Amp Circuit

High Gbw Op-Amp Circuit

Unity-Gain Noninverting Amplifier Circuit

Nonlinear Operational Amplifier Circuit

Amplifier-for-signal-supply

Constant-bandwidth-amplifier

Op Amp Regulator

Thermocouple-preamplifier

Precision-Increasing Buffer

Wide-range-digitally-controlled-variable-gain-amplifier

Fast Composite Amplifier Circuit

3Input And Gate Comparator

Low-Offset Simple Video Buffer Circuit

Make Lm324 Op Amp Swing Rail-To-Rail

Summing-amplifier

Programmable-gain-differential-input-amplifier

Current-booster

Instrumentation-amplifier

Wideband-instrumentation-amplifier

Differential-instrumentation-amplifier

Wide-band-agc-amplifier

Noninverting-programmable-gain-amplifier

Buffer Amplifiers Circuit

Composite-amplifier

Strain-gauge-instrumentation-amplifier

Inverting Summing Amplifier Circuit

Photodiode-amplifier

Low-input-capacitance-buffer

Efficient Power Booster

Protected Intrinsically Safe Op Amp Circuit

15V-chopper-amplifier

Programmable-amplifier

Current-shunt-amplifier

Cascaded-amplifier

Ultra-precision-instrumentation-amplifier

Inverting-programmable-gain-amplifier

Norton-amplifier

Increased Feedback-Stabilized Amplifier

Write-amplifier

Compound Op Amp Vco Driver

Stabilized-amplifier

Differential-amplifier

Noise Blanker

Single supply AC buffer amplifier

Gain-Controlled Op Amp

Operational-amplifiers

High impedance low capacitance wideband buffer

Bidirectional Compound Op Amp

Biomedical-instrumentation-differential-amplifier

Active-limiting-amplifier

Oscillator Buffers

PAL powers universal ISA bus interface

CCD Array Reader Project

Simple FIFO provides data-width conversion

Homemade PBX

Off-the-shelf ICs make 10-bit convolver

LED Display controller

4-Way Intercom

LED or Lamp Pulser

dot-matrix LED

Video amplifier

VERY LOW POWER GATED CRYSTAL OSCILLATOR

Tunable IF with TDA7000

4-transistor H-bridge

PC controls inexpensive waveform generator

The "BEAM Stepper" drive circuit

Active SubWoofer

Accelerometer Scale Factor and Offset Adjustments

PC monitors two-way RS-232 transmission

STK200/STK300 ISP Header