New Circuits Page 219
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The amplifier can be assembled by a reasonably experienced hobbyist in about three hours. The metalwork will take somewhat longer, and this is especially true for the high continuous power variant. Even so, it is simple to build, compact, relatively....
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This is the schematic of the final design including the tone stack but leaving out the volume, balance, and sonic controls. The right half of the circuit is John Broskie's original White cathode amplifier with a pair of 5687s as output tubes. This lowers the....
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This circuit is a 20W Audio Amplifier kit, based on the TDA2005 IC, a class B dual audio amplifier, specifically designed for car radio applications etc. Power supply - 18 VDC. Output power - 20 W, 4 ?. IC built in Thermal Shut-down, Load dump voltage surge....
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This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while a similar switch S2 controls reverse (volume decrease)....
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Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will....
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The circuit in Figure 1 can solve this problem by providing a constant 300-mV drop between VIN and VOUT at currents as high as 3A. The accuracy of the 300-mV drop is nearly as good as the accuracy of the input voltage, which in this case is approximately 1%.....
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This project is one for the experimenter, but as shown will work extremely well. The sensing circuit can be made so sensitive that a load of only 2.5mA is enough for the circuit to detect, and disconnect the charger.
The idea is that the charger is left....
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This interface circuit provides electrically isolated RS485 communication inteface to the PC serial port the isolation circuit protect the PC from direct connection to hazardous voltages...
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If the voltage at the input exceeds the voltage on the capacitor, then the output of the 741 goes positive, the diode conducts, and the capacitor is charged up to the input voltage-forward voltage drop of diode. When the voltage at the input is less than....
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A small neon lamp is triggered into conduction by the telephone's ringing voltage, passes just enough current to activate the LED in optocoupler Ul, which in turn triggers the 6-A Triac that controls 12—a 117-Vac lamp or bell. (Capacitor Cl is necessary....
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This circuit flashes an LED to indicate that your phone rang during your absence. A differential amplifier with hyste..
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When the light incident on the LASCR is interrupted, the voltage at the anode to the 2N4990 unilateral switch goes positive on the next positive cycle of the power which in turn triggers the switch and the C230 SCR when the switching voltage of the....
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The circuit in Fig. 1 uses a single bicolor LED to
indicate both power-on and blown-fuse conditions.
Regardless of the condition of the fuse, the green
side of the LED is always on for each positive
half-cycle of the ac input. With a 120Vrms ac
input....
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With only three components and a buffer, a line frequency square wave having a 1:1 duty cycle may be derived from the power supply. During the alternate half-cycle, however, A is effectively clamped to - 0.7 V by Dl in the bridge which offsets the forward....
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This circuit will record commentary and/ or music on one track of a tape and put the beeps that change the slides on another track. Gate U2a is used to trigger U1, which is configured as a timer when a pulse is received from either the tape input or via....
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This design notes shows a UHF 3-element portable antenna with gamma-match...
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This is a 3 stage discrete amplifier with gain control. Alternative transistors such as BC109C, BC548, BC549, BC549C may be used with little change in performance. The first stage built around Q1 operates in common base configuration. This is unusuable in....
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Application Note 381 contains information necessary to interface the Motorola MPC8260 processor to the DS2155 T1/E1/J1 Single Chip Transceiver (SCT). The application note covers interfacing both the address and data processor bus and the communications....
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A self-interrupting device connected to a voltage source functions as a switch that repeatedly open..
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Often the frequency of a signal must be doubled: modulator/demodulator chip LM1496 is an ideal basis for this. From..
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The human speech apprehend a small area of frequencies, that is extended from 300HZ until 3KHZ. This spectrum is also internationally recognized for the transmission of speech via telecommunications networks. This is also the mainer use of this circuit, one....
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Voltage is applied to the chip via pins 14 and 7 so that when power is applied to the project, the high and low frequency oscillators will come into operation to produce a wailing sound from the piezo.
The high frequency oscillator is the only tone sent to....
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A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale current of the meter movement. So, if you have a 1 milliamp meter and you want to read 0-10 volts....
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his chapter shows how to connect an analogue signal to a PIC. An analogue signal is similar to a sine wave and is generally less than 5v (5,000mV) in amplitude. Low-level signals are generally expressed in mV, to make them instantly recognisable and easy to....
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The basis for this amplifier has been around now for several years as Project 3A, and requires only relatively small modifications to be able to operate in Class-A. The biggest change is in output power (reduced dramatically from the 60-100W of the Class-AB....
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A stereo power amplifier is limited in its output power by two main factors - the impedance of the load and the internal power supply voltage. To obtain more power, one has very limited choices - other than the purchase of a more powerful amp...
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This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen.
When power supply is restored,....
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Amateur Radio Transmitters using valves such as 807 or1625 works well with a plate voltage between 600V to 700 Volts.The circuit described here is a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output will....
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The MC34012 tone-ringer chip derives its power by rectifying the ac ringing signal. That signal is normally at 20 Hz and measures between 70 and 130 volts rms. It uses that power for the tone generator and to drive the piezoelectric transducer. The sound....
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Simple half-wave motor speed control is effective for use with small universal (ac/dc) motors. Maximum current capability 2 amps RMS. Because speed-dependent feedback is provided, the control gives excellent torque characteristics to the motor, even at low....
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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....
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Two simple arrangementsfor resistive loads are shown in A & B. The circuit in A will provide load power when the actuating contact is closed, and no power when the contact is open. B provides the reverse of this action-power being supplied to the load when....
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The three-channel amplifier output distribution uses a single TL084. The first step is to capacitive coupling with a p. 1.0 ~ electrolytic capacitor. The entries are railways Vee Y2 or 4.5 V. This allows using a single 9 V power supply A voltage gain of 10....
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The heart of the circuit is a 555 oscillator /timer, Ul, configured for monostable operation. The output of Ul at pin 3 is tied to the gate of SCRl. As long as Sl-S5, which are connected to the trigger input of Ul, are open, the circuit remains in the....
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Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope"s three-pronged power plug. You can avoid this problem by using the ground-noise tester shown. Powered by two 9-V batteries, the circuit....
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This closed-loop peak detector circuit uses a Schottky diode inside feedback loop to obtain good accuracy. The 20- resistance RQ isolates the 0.01- load and prevents oscillation. The dc value is read with a DVM. At a low frequency, the error is small and....
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Two important properties of the 8043 are used to advantage in this circuit. The low input bias currents give rise to slow output decay rates (droop) in the hold mode, while the high slew rate at 6 V/p,s improves the tracking speed and the response time of....
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Here is a simple method of series connection into the telephone set suitable for PABX or short line applications. When the telephone handset is lifted, Cl is charged via D1 to (Vz1 -0.7) V and DF320 power on reset occurs. When the first keyed digit is....
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* Flashing frequency can be varied by changing R1 value in the 1M - 4M7 range.
* This circuit is very efficient when driving a small 3.2V incandescent lamp. In this case omit the LED and R3, connecting the bulb across Q2 Collector and positive supply,....
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The design goals of this circuit were efficiency, simplicity, reliability and the use of field replaceable parts. A medium power solar system can be built with the SCC3, a 12V (nominal) solar panel that is rated from 100 milliamps to 20 amps, and a lead acid....
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When the power is connected to the circuit by turning on SW2, RELAY1 get energized for the time it get for it to load C3 through R1 and R3. After that the relay get de-energized, C3 gets discharged through R2 and R4. The setting of R2 determines the....
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This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the....
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The LT®1316, a
micropower step-up DC/DC converter with peak switch
current control, meets these needs. The device draws 33mA
quiescent current and contains a 0.6W, 30V switch that can
be programmed for a maximum peak current between
30mA and 600mA with....
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The add-on circuit presented here is useful for stereo systems. This circuit has provision for connecting stereo outputs from four different sources/channels as inputs and only one of them is selected/connected to the output at any one time.
When power....
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The circuit is a preamplifier with digital regulation intensity of sound. He is separated in three departments. In first schematic (Fig.1), is found the circuit of control of electronic potesometer. The control become from two pressing switches. The S1 (UP),....
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The level at which the limiter kicks in audio can be adjusted with the selector knob LIMIT LEVEL. When this level is exceeded, the output of the half-LIMITING detector of the op-amp (used as a comparator) turns the LED causes the resistance of the....
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This document is an introduction to the Wideband Fuel Mixture Display (FMD). We modified the original Silicon Chip Fuel Mixture Display (that used a narrowband sensor) for use as a display for the DIY-WB wideband oxygen sensor controller. After first....
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It will accept AC from 6v to 18v or DC from 9v to 18v and any current up to 1 amp.
The diode bridge on the input converts AC to DC and it doesn't matter which way around the leads are connected as the diodes compensate for either direction.
If a DC plug....
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Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere. It detects RF via a square law detector, basically its a crystal set with....
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The design shown will test PNP and NPN transistors, diodes and SCRs both "in-situ" (equipment of course de-energised) and also by direct connection to a stand-alone component. It is a simple GO/NOGO test which can identify diode and transistor action and....
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Sound effects generators trying to imitate rain sound or sea surf are well known to hobbyists from many years: their purpose is to induce relaxation and sleep or to help in concentration and study. The sound generated is restrained to a background level and....
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The first idea they was to work with 8.867238 MHz crystal (2 times the color carrier). When I read more about PAL video composite signal creation, I saw that, if you want to product colors entire-in-software you must to create the color-carrier (4.43 MHz),....
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The block diagram in Figure 1 shows how to make a cable-free, direct-video system. The system allows users to walk from booth to booth at an exhibition to interview people and to display the interviews in real time on three screens at key locations...
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This circuit is an oscillator at frequency 10MHZ, using IC 1A and IC1B and a frequency divider. Using the IC2 it divides the pulses to 10. IC1C is a buffer. The variable capacitor 39pF is microtunig the frequency . The pin 12 of the IC2 is the output, where....
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The circuit in Figure 1 is a simple, low-cost voltage-to-time converter using the ubiquitous 555 timer chip. You can use the IC`s monostable multivibrator as a voltage-to-time converter by connecting the analog-voltage input to the charging resistor, R,....
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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....
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The circuit of Figure 1 shows how you can configure a FIFO memory, a static SRAM, and a bus register to generate fast hardware histograms for linearity tests and still allow straight data acquisition for other tests. The main purpose of the FIFO memory is to....
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The analog input is fed into the span resistor of a DAC. The analog input voltage range is selectable in the same way as the output voltage range of the DAC. The net current flow through the ladder termination resistance; i.e., 2 KO for HI-562A; produces....
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Capable of 2kW peak and a minimum of 1.5kW continuous, it has to be said that this amplifier will blow up any speaker connected to it. Regardless of the claimed power that various drivers can handle, they can`t. To put this whole issue into perspective, take....
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This circuit protects microprocessor systems from "brownouts" without the expense of an uninterruptible power supply. Designed around a small 9-V nickel cadmium battery the circuit continues to provide a constant 5-V output during brownouts of up to a few....
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The MIDI Drum Machine began in the Fall of 1991 as a project for a microprocessor system design course, shortly after I wrote PAULMON1, the 8051 monitor/debugger. A friend, Rod Seely, both a musician and electronics hobbiest suggested I design something....
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There have been a lot of transistor tester circuits in recent electronics magazines, but this one is different. It has more features and includes a signal injector so you can test audio sections of radios and the front end of FM transmitters etc. The major....
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Since the circuit operates at greater than mains potential and is not isolated by a transformer, it is extremely dangerous. The DC operating potential is about 340V, and there is more than enough stored charge to kill you many times over (although in my....
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Many times we needed to strengthen a small signal in the region of VHF or FM. The preamplifier that to you we propose offers 20dB in all the region of VHF and it still can reach also their 500MHZ. The amplifier is a circuit of high frequency RF with....
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The Elect. Sel. 8 is a simple circuit, with a choice of 8 sources of any sort ,of 8 independent switches. Each switch corresponding with a relay for example the switch S1 activates the RL1 e.t.c. The uses of the circuit are quite a few, choice of entrances....
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This circuit uses a CA3240 dual BiMOS op amp to sense small currents flowing between the contact points on a touch plat..
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This SCR pre-regulator keeps the filter capacitor Vc, in a variable output power supply, a few volts above the output voltage V0. The benefits include: less heat dissipated by the pass transistor and therefore small heatsink, cooler operation and higher....
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Here is the latest and greatly improved TX200 VFO/VCO FM transmitter. The most versatile transmitter to date that can be turned into high fidelity stereo PLL based 200mW FM transmitter. It is a perfect circuit for transmitting your music around the house and....
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The TX500 is a simple to build 500mW FM Transmitter. It consists of three blocks; modulator / oscillator, two stage 500mW VHF amplifier and LED based power meter. The TX500 allows to transmit audio signals to FM band at frequencies from 88 MHz to 108 MHz.....
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This is two three pole bandpass filters with the HPF Fo about 50Hz and the LPF Fo about 15kHz. This limits the input bandwidth to the phase sequence array, which can produce 90° phase shifts only over a limited bandwidth. The array is driven with a true and....
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This PWM control circuit provides the control pulse to the DMOS Power Switch in the flyback circuit. The output of the PWM is a pulse whose width is proportional to the input control voltage and whose repetition rate is determined by an external clock....
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This project takes advantage from -HOLD input, which is connected to push-button P1. As long as the -HOLD input is low, truth table's timeouts have no effect because this input serves to disable any state change provoked by timers. The effect is to freeze....
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The FM modulator is built with a Motorola MC1648P oscillator. Two varactors, Motorola MV-209, are used to frequency modulate the oscillator. The 5000- potentiometer is used to bias the varactors for best linearity. The output frequency of approximately 100....
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A quick circuit showing how to control the speed of a DC motor with a potentiometer with your Arduino board. Also shows how to use a TIP120 transistor to allow the Arduino control a larger power supply...
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so what happens when you flip a switch? When you try to stop the flow of current in 'zero' time its equivalent to trying to stop a freight train instantaneously. you get a huge voltage buildup "dv/dt" = "X/0=infinity This is one example of the use of a....
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The capacitors needed for the power supply are massive to try to get rid of hum, and massive means expensive. The "improved" Zen is a little better, since it uses an inductor (or choke) in the supply - obviously the hum drove someone mad. Inductors are....
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This headphone buffer is based on Greg Szekeres' MOSFET Headphone Driver. It is a robust and reliable zero feedback, class A circuit. [Editor: And like the Szekeres MOSFET amp, this amp has unity voltage gain. Therefore, the audio source must supply adequate....
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The circuit in Figure 1 adapts a small key-chain voice recorder to the Tip and Ring lines of a phone line that has been disconnected from the central office. The purpose is to play a prerecorded message into any phone on the line when its receiver goes....
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Various embodiments of the BB metal detector have been published, and it has been widely described in the press as a new genre. Instead of using a search and a reference oscillator as with BFO, or Tx and Rx coils as with IB, it uses two transmitters or....
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This circuit is a simple adapter for PC parallel port to think that there is a printer connected to computer. This adapter is useful for testing printing speed with different software and as a part of your own designs. You can use this circuit to connect....
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In this project it was used the ?Piranha Super-flux RGB? Led of common anode, and the PIC18F25K20, in order to generate combinations of colors. It has two function modes, automatic that generate the color sequence that is stored in the ?C memory, and the....
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Simple, portable phase-sequence indicator determines the proper phase rotation in polyphase circuits. Major components are two neon lamps, two resistors, and a capacitor. In operation, the leg voltages are unbalanced, so that the lamp with the maximum....
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In this circuit, data at input C is amplified by IC2 and then fed to modulator IC1. IC1 g..
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Otherwise properly mixed sounds often suffer from a predominant solo voice (which might, of course, be the intention). If ..
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A simple method of deriving a center or third channel without the use of an extra transformer or ampli..
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This circuit lights up ten bulbs sequentially, first in one direc- tion and then in the opposite direction, thus presenting a nice visual effect. In this circuit, gates N1 and N2 form an oscillator. The output of this oscillator is used as a clock for BCD....
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Here is a simple audio amplifier circuit that is easy to build and has few components. This circuit is built around the LM386 (click for datasheet) audio amplifier integrated circuit, useful when you need to power medium sized speakers from a music player....
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The problems that exist in common crossover networks are known. The low-pass filter causes delay in the signal. On the contrary the high-pass filter causes be pre-ahead in the signal that it in goes through from this. So, the cross-frequency are created....
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This novel buzzer circuit uses a relay in series with a small audio transformer and speaker. When the switch is pressed, the relay will operate via the transformer primary and closed relay contact. As soon as the relay operates the normally closed contact....
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4 simple 12Vdc power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you....
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A simple tester can be used for routine checks for resistance on production lines of relays, coils, or similar components where frequent changes in resistance to be tested are not required. The tester is built around a single quad op amp chip, the LM324. R,....
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This circuit is basically a system that generates a pulsed modulation signal for a Gunn diode microwave oscillator. Several speed settings are preset (S3 a and b). A 555 timer is used with a frequency divider chain to produce Doppler shift equivalents of....
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Here is a telephone line vigilant circuit to guard against mis- use of your telephone lines. It monitors telephone lines round the clock and provides visual as well as an audio warning (when someone is using your telephone lines) which can be heard anywhere....
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A basic circuit of the 89C2051 shown here can be made easily using point-to-point soldering with a universal PCB. Use an ordinary 20-pin socket, do not use a circle-pin socket. D1 is a small dot LED. U2 can be either 7805 or 78L05. U3 is optional for....
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A simple detector of radar signals uses the junctions of the input transistors of an LM1458 op amp as RF detectors. The lead..
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The base of Ql is connected to the car"s ignition circuit. One side of the piezoelectric buzzer is connected to the instrument-panellight fuse. When the headlights are off,. no current reaches the buzzer, and therefore nothing happens. What happens when....
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These circuits provide a means of altering the YELLOW output of RED / GREEN type two colour light emitting diodes. These circuits use the LM555 timer chip...
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Using ac-line power sources and batteries for remote humidity sensors is undesirable because these sources can be troublesome if you mount them in inaccessible points, such as smokestacks, cold-storage chambers, or darkrooms, where maintenance is difficult....
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U1A, an op amp, oscillates at the frequency at which the phase shift in the Wien bridge network is exactly zero degrees. Changing bridge component values changes the oscillator frequency. In this circuit, we need change only the two resistors to do this. S1A....
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This circuit allows a microprocessor system to measure its own battery voltage. A Texas Instrument TI43..
The amplifier can be assembled by a reasonably experienced hobbyist in about three hours. The metalwork will take somewhat longer, and this is especially true for the high continuous power variant. Even so, it is simple to build, compact, relatively....
This is the schematic of the final design including the tone stack but leaving out the volume, balance, and sonic controls. The right half of the circuit is John Broskie's original White cathode amplifier with a pair of 5687s as output tubes. This lowers the....
This circuit is a 20W Audio Amplifier kit, based on the TDA2005 IC, a class B dual audio amplifier, specifically designed for car radio applications etc. Power supply - 18 VDC. Output power - 20 W, 4 ?. IC built in Thermal Shut-down, Load dump voltage surge....
This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch S1 controls the forward (volume increase) operation of both channels while a similar switch S2 controls reverse (volume decrease)....
Each zone uses a normally closed contact. These can be micro switches or standard alarm contacts (usually reed switches). Zone 1 is a timed zone which must be used as the entry and exit point of the building. Zones 2 - 5 are immediate zones, which will....
The circuit in Figure 1 can solve this problem by providing a constant 300-mV drop between VIN and VOUT at currents as high as 3A. The accuracy of the 300-mV drop is nearly as good as the accuracy of the input voltage, which in this case is approximately 1%.....
This project is one for the experimenter, but as shown will work extremely well. The sensing circuit can be made so sensitive that a load of only 2.5mA is enough for the circuit to detect, and disconnect the charger. The idea is that the charger is left....
This interface circuit provides electrically isolated RS485 communication inteface to the PC serial port the isolation circuit protect the PC from direct connection to hazardous voltages...
If the voltage at the input exceeds the voltage on the capacitor, then the output of the 741 goes positive, the diode conducts, and the capacitor is charged up to the input voltage-forward voltage drop of diode. When the voltage at the input is less than....
A small neon lamp is triggered into conduction by the telephone's ringing voltage, passes just enough current to activate the LED in optocoupler Ul, which in turn triggers the 6-A Triac that controls 12—a 117-Vac lamp or bell. (Capacitor Cl is necessary....
This circuit flashes an LED to indicate that your phone rang during your absence. A differential amplifier with hyste..
When the light incident on the LASCR is interrupted, the voltage at the anode to the 2N4990 unilateral switch goes positive on the next positive cycle of the power which in turn triggers the switch and the C230 SCR when the switching voltage of the....
With only three components and a buffer, a line frequency square wave having a 1:1 duty cycle may be derived from the power supply. During the alternate half-cycle, however, A is effectively clamped to - 0.7 V by Dl in the bridge which offsets the forward....
This circuit will record commentary and/ or music on one track of a tape and put the beeps that change the slides on another track. Gate U2a is used to trigger U1, which is configured as a timer when a pulse is received from either the tape input or via....
This is a 3 stage discrete amplifier with gain control. Alternative transistors such as BC109C, BC548, BC549, BC549C may be used with little change in performance. The first stage built around Q1 operates in common base configuration. This is unusuable in....
A self-interrupting device connected to a voltage source functions as a switch that repeatedly open..
Often the frequency of a signal must be doubled: modulator/demodulator chip LM1496 is an ideal basis for this. From..
The human speech apprehend a small area of frequencies, that is extended from 300HZ until 3KHZ. This spectrum is also internationally recognized for the transmission of speech via telecommunications networks. This is also the mainer use of this circuit, one....
Voltage is applied to the chip via pins 14 and 7 so that when power is applied to the project, the high and low frequency oscillators will come into operation to produce a wailing sound from the piezo. The high frequency oscillator is the only tone sent to....
A milliamp meter can be used as a volt meter by adding a series resistance. The resistance needed is the full scale voltage reading divided by the full scale current of the meter movement. So, if you have a 1 milliamp meter and you want to read 0-10 volts....
his chapter shows how to connect an analogue signal to a PIC. An analogue signal is similar to a sine wave and is generally less than 5v (5,000mV) in amplitude. Low-level signals are generally expressed in mV, to make them instantly recognisable and easy to....
The basis for this amplifier has been around now for several years as Project 3A, and requires only relatively small modifications to be able to operate in Class-A. The biggest change is in output power (reduced dramatically from the 60-100W of the Class-AB....
A stereo power amplifier is limited in its output power by two main factors - the impedance of the load and the internal power supply voltage. To obtain more power, one has very limited choices - other than the purchase of a more powerful amp...
This circuit is permanently plugged into a mains socket and NI-CD batteries are trickle-charged. When a power outage occurs, the lamp automatically illuminates. Instead of illuminating a lamp, an alarm sounder can be chosen. When power supply is restored,....
Amateur Radio Transmitters using valves such as 807 or1625 works well with a plate voltage between 600V to 700 Volts.The circuit described here is a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output will....
The MC34012 tone-ringer chip derives its power by rectifying the ac ringing signal. That signal is normally at 20 Hz and measures between 70 and 130 volts rms. It uses that power for the tone generator and to drive the piezoelectric transducer. The sound....
Simple half-wave motor speed control is effective for use with small universal (ac/dc) motors. Maximum current capability 2 amps RMS. Because speed-dependent feedback is provided, the control gives excellent torque characteristics to the motor, even at low....
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....
Two simple arrangementsfor resistive loads are shown in A & B. The circuit in A will provide load power when the actuating contact is closed, and no power when the contact is open. B provides the reverse of this action-power being supplied to the load when....
The three-channel amplifier output distribution uses a single TL084. The first step is to capacitive coupling with a p. 1.0 ~ electrolytic capacitor. The entries are railways Vee Y2 or 4.5 V. This allows using a single 9 V power supply A voltage gain of 10....
The heart of the circuit is a 555 oscillator /timer, Ul, configured for monostable operation. The output of Ul at pin 3 is tied to the gate of SCRl. As long as Sl-S5, which are connected to the trigger input of Ul, are open, the circuit remains in the....
Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope"s three-pronged power plug. You can avoid this problem by using the ground-noise tester shown. Powered by two 9-V batteries, the circuit....
This closed-loop peak detector circuit uses a Schottky diode inside feedback loop to obtain good accuracy. The 20- resistance RQ isolates the 0.01- load and prevents oscillation. The dc value is read with a DVM. At a low frequency, the error is small and....
Two important properties of the 8043 are used to advantage in this circuit. The low input bias currents give rise to slow output decay rates (droop) in the hold mode, while the high slew rate at 6 V/p,s improves the tracking speed and the response time of....
Here is a simple method of series connection into the telephone set suitable for PABX or short line applications. When the telephone handset is lifted, Cl is charged via D1 to (Vz1 -0.7) V and DF320 power on reset occurs. When the first keyed digit is....
* Flashing frequency can be varied by changing R1 value in the 1M - 4M7 range. * This circuit is very efficient when driving a small 3.2V incandescent lamp. In this case omit the LED and R3, connecting the bulb across Q2 Collector and positive supply,....
The design goals of this circuit were efficiency, simplicity, reliability and the use of field replaceable parts. A medium power solar system can be built with the SCC3, a 12V (nominal) solar panel that is rated from 100 milliamps to 20 amps, and a lead acid....
When the power is connected to the circuit by turning on SW2, RELAY1 get energized for the time it get for it to load C3 through R1 and R3. After that the relay get de-energized, C3 gets discharged through R2 and R4. The setting of R2 determines the....
This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor`s output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the....
The add-on circuit presented here is useful for stereo systems. This circuit has provision for connecting stereo outputs from four different sources/channels as inputs and only one of them is selected/connected to the output at any one time. When power....
The circuit is a preamplifier with digital regulation intensity of sound. He is separated in three departments. In first schematic (Fig.1), is found the circuit of control of electronic potesometer. The control become from two pressing switches. The S1 (UP),....
The level at which the limiter kicks in audio can be adjusted with the selector knob LIMIT LEVEL. When this level is exceeded, the output of the half-LIMITING detector of the op-amp (used as a comparator) turns the LED causes the resistance of the....
This document is an introduction to the Wideband Fuel Mixture Display (FMD). We modified the original Silicon Chip Fuel Mixture Display (that used a narrowband sensor) for use as a display for the DIY-WB wideband oxygen sensor controller. After first....
It will accept AC from 6v to 18v or DC from 9v to 18v and any current up to 1 amp. The diode bridge on the input converts AC to DC and it doesn't matter which way around the leads are connected as the diodes compensate for either direction. If a DC plug....
Useful as a transmitter tune-up meter or an RF sniffer, this is an RF field strength indicator that is loosely based on the Broad Band RF Field Strength Probe, described elsewhere. It detects RF via a square law detector, basically its a crystal set with....
The design shown will test PNP and NPN transistors, diodes and SCRs both "in-situ" (equipment of course de-energised) and also by direct connection to a stand-alone component. It is a simple GO/NOGO test which can identify diode and transistor action and....
Sound effects generators trying to imitate rain sound or sea surf are well known to hobbyists from many years: their purpose is to induce relaxation and sleep or to help in concentration and study. The sound generated is restrained to a background level and....
The first idea they was to work with 8.867238 MHz crystal (2 times the color carrier). When I read more about PAL video composite signal creation, I saw that, if you want to product colors entire-in-software you must to create the color-carrier (4.43 MHz),....
This circuit is an oscillator at frequency 10MHZ, using IC 1A and IC1B and a frequency divider. Using the IC2 it divides the pulses to 10. IC1C is a buffer. The variable capacitor 39pF is microtunig the frequency . The pin 12 of the IC2 is the output, where....
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....
The analog input is fed into the span resistor of a DAC. The analog input voltage range is selectable in the same way as the output voltage range of the DAC. The net current flow through the ladder termination resistance; i.e., 2 KO for HI-562A; produces....
Capable of 2kW peak and a minimum of 1.5kW continuous, it has to be said that this amplifier will blow up any speaker connected to it. Regardless of the claimed power that various drivers can handle, they can`t. To put this whole issue into perspective, take....
This circuit protects microprocessor systems from "brownouts" without the expense of an uninterruptible power supply. Designed around a small 9-V nickel cadmium battery the circuit continues to provide a constant 5-V output during brownouts of up to a few....
The MIDI Drum Machine began in the Fall of 1991 as a project for a microprocessor system design course, shortly after I wrote PAULMON1, the 8051 monitor/debugger. A friend, Rod Seely, both a musician and electronics hobbiest suggested I design something....
There have been a lot of transistor tester circuits in recent electronics magazines, but this one is different. It has more features and includes a signal injector so you can test audio sections of radios and the front end of FM transmitters etc. The major....
Since the circuit operates at greater than mains potential and is not isolated by a transformer, it is extremely dangerous. The DC operating potential is about 340V, and there is more than enough stored charge to kill you many times over (although in my....
Many times we needed to strengthen a small signal in the region of VHF or FM. The preamplifier that to you we propose offers 20dB in all the region of VHF and it still can reach also their 500MHZ. The amplifier is a circuit of high frequency RF with....
The Elect. Sel. 8 is a simple circuit, with a choice of 8 sources of any sort ,of 8 independent switches. Each switch corresponding with a relay for example the switch S1 activates the RL1 e.t.c. The uses of the circuit are quite a few, choice of entrances....
This circuit uses a CA3240 dual BiMOS op amp to sense small currents flowing between the contact points on a touch plat..
This SCR pre-regulator keeps the filter capacitor Vc, in a variable output power supply, a few volts above the output voltage V0. The benefits include: less heat dissipated by the pass transistor and therefore small heatsink, cooler operation and higher....
Here is the latest and greatly improved TX200 VFO/VCO FM transmitter. The most versatile transmitter to date that can be turned into high fidelity stereo PLL based 200mW FM transmitter. It is a perfect circuit for transmitting your music around the house and....
The TX500 is a simple to build 500mW FM Transmitter. It consists of three blocks; modulator / oscillator, two stage 500mW VHF amplifier and LED based power meter. The TX500 allows to transmit audio signals to FM band at frequencies from 88 MHz to 108 MHz.....
This is two three pole bandpass filters with the HPF Fo about 50Hz and the LPF Fo about 15kHz. This limits the input bandwidth to the phase sequence array, which can produce 90° phase shifts only over a limited bandwidth. The array is driven with a true and....
This PWM control circuit provides the control pulse to the DMOS Power Switch in the flyback circuit. The output of the PWM is a pulse whose width is proportional to the input control voltage and whose repetition rate is determined by an external clock....
This project takes advantage from -HOLD input, which is connected to push-button P1. As long as the -HOLD input is low, truth table's timeouts have no effect because this input serves to disable any state change provoked by timers. The effect is to freeze....
The FM modulator is built with a Motorola MC1648P oscillator. Two varactors, Motorola MV-209, are used to frequency modulate the oscillator. The 5000- potentiometer is used to bias the varactors for best linearity. The output frequency of approximately 100....
A quick circuit showing how to control the speed of a DC motor with a potentiometer with your Arduino board. Also shows how to use a TIP120 transistor to allow the Arduino control a larger power supply...
so what happens when you flip a switch? When you try to stop the flow of current in 'zero' time its equivalent to trying to stop a freight train instantaneously. you get a huge voltage buildup "dv/dt" = "X/0=infinity This is one example of the use of a....
The capacitors needed for the power supply are massive to try to get rid of hum, and massive means expensive. The "improved" Zen is a little better, since it uses an inductor (or choke) in the supply - obviously the hum drove someone mad. Inductors are....
This headphone buffer is based on Greg Szekeres' MOSFET Headphone Driver. It is a robust and reliable zero feedback, class A circuit. [Editor: And like the Szekeres MOSFET amp, this amp has unity voltage gain. Therefore, the audio source must supply adequate....
Various embodiments of the BB metal detector have been published, and it has been widely described in the press as a new genre. Instead of using a search and a reference oscillator as with BFO, or Tx and Rx coils as with IB, it uses two transmitters or....
This circuit is a simple adapter for PC parallel port to think that there is a printer connected to computer. This adapter is useful for testing printing speed with different software and as a part of your own designs. You can use this circuit to connect....
In this project it was used the ?Piranha Super-flux RGB? Led of common anode, and the PIC18F25K20, in order to generate combinations of colors. It has two function modes, automatic that generate the color sequence that is stored in the ?C memory, and the....
Simple, portable phase-sequence indicator determines the proper phase rotation in polyphase circuits. Major components are two neon lamps, two resistors, and a capacitor. In operation, the leg voltages are unbalanced, so that the lamp with the maximum....
In this circuit, data at input C is amplified by IC2 and then fed to modulator IC1. IC1 g..
Otherwise properly mixed sounds often suffer from a predominant solo voice (which might, of course, be the intention). If ..
A simple method of deriving a center or third channel without the use of an extra transformer or ampli..
This circuit lights up ten bulbs sequentially, first in one direc- tion and then in the opposite direction, thus presenting a nice visual effect. In this circuit, gates N1 and N2 form an oscillator. The output of this oscillator is used as a clock for BCD....
Here is a simple audio amplifier circuit that is easy to build and has few components. This circuit is built around the LM386 (click for datasheet) audio amplifier integrated circuit, useful when you need to power medium sized speakers from a music player....
The problems that exist in common crossover networks are known. The low-pass filter causes delay in the signal. On the contrary the high-pass filter causes be pre-ahead in the signal that it in goes through from this. So, the cross-frequency are created....
This novel buzzer circuit uses a relay in series with a small audio transformer and speaker. When the switch is pressed, the relay will operate via the transformer primary and closed relay contact. As soon as the relay operates the normally closed contact....
4 simple 12Vdc power supply circuits with output voltages around 12V. First power supply circuit is built with BD139, one zener diode and a few passive components. Each of the schematic is very simple to construct and will function without problems if you....
A simple tester can be used for routine checks for resistance on production lines of relays, coils, or similar components where frequent changes in resistance to be tested are not required. The tester is built around a single quad op amp chip, the LM324. R,....
This circuit is basically a system that generates a pulsed modulation signal for a Gunn diode microwave oscillator. Several speed settings are preset (S3 a and b). A 555 timer is used with a frequency divider chain to produce Doppler shift equivalents of....
Here is a telephone line vigilant circuit to guard against mis- use of your telephone lines. It monitors telephone lines round the clock and provides visual as well as an audio warning (when someone is using your telephone lines) which can be heard anywhere....
A basic circuit of the 89C2051 shown here can be made easily using point-to-point soldering with a universal PCB. Use an ordinary 20-pin socket, do not use a circle-pin socket. D1 is a small dot LED. U2 can be either 7805 or 78L05. U3 is optional for....
A simple detector of radar signals uses the junctions of the input transistors of an LM1458 op amp as RF detectors. The lead..
The base of Ql is connected to the car"s ignition circuit. One side of the piezoelectric buzzer is connected to the instrument-panellight fuse. When the headlights are off,. no current reaches the buzzer, and therefore nothing happens. What happens when....
These circuits provide a means of altering the YELLOW output of RED / GREEN type two colour light emitting diodes. These circuits use the LM555 timer chip...
U1A, an op amp, oscillates at the frequency at which the phase shift in the Wien bridge network is exactly zero degrees. Changing bridge component values changes the oscillator frequency. In this circuit, we need change only the two resistors to do this. S1A....
This circuit allows a microprocessor system to measure its own battery voltage. A Texas Instrument TI43..
