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8051 / 8052
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H Bridge Circuit
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4 Band Resistor
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Astable Oscillator Circuits
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Crystal Oscillator Circuits
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RF Oscillator Circuits
Sine Wave Oscillator Circuits
Square Wave Oscillator Circuits
Volt Controlled Oscillator Circuits
Wein Bridge Oscillator Circuits
Pierce Oscillator Circuits
Low-Frequency Crystal Oscillator Circuit
Ql, Q2, and the associated circuitry form a modified astable multivibrator in which the loop gain is automatically adjusted to the threshold of oscillation by means of field effect transistor Q3. Q4 linearly amplifies the signal present at the collector of Q2 and isolates the oscillator section of the circuit from the output. This stage...
Easy Crystal Impedance Checker Circuit
On occasion, microprocessors/microcomputers and microprocessor crystals just aren`t compatible with each other. Many microprocessor data sheets specify maximum values for a crystal`s equivalent series resistance (Rs) that aren`t met by some crystals advertised for microprocessor/ microcomputer use. As a result, a crystal with an Rs value...
Frequency Multiplier Without Pll Circuit
An input rectangular signal is differentiated and short impulses are formed from its edges. These impulses write the content of counter A to a latch that clears the counter after a very short time. Counter A counts impulses of the frequency fo that are much greater than that of the input signal. The pulses come from an impulse generator. Thus,...
Function Generator Circuit
A quad op amp makes up the heart of this function generator. Ul-a generates a square wave, and outputs this to J8. J1 and J2 are pulse outputs obtained by differentiating the square wave. Integrator Ul-b generates a triangle-wave shaper to obtain a sine wave.
Triangle-Wave Generator Circuit
This is a simple triangle-wave generator using two IC devices and a transistor. The triangle wave is used as feedback to the square-wave generator. SI allows range switching in three ranges from 100 Hz to 100 kHz.
Triangle- And Square-Wave Generator Circuit
The circuit will generate precision triangle and square waves. The output amplitude of the square wave is set by the output swing of op amp Al, xndRl/R2 sets the triangle amplitude. The frequency of oscillation in either case is approximately l/0.69ftC. The square wave will maintain 50% duty cycleeven if the amplitude of the oscillation is not...
Second-Order Polynomial Generator Circuit
By using a circuit built with a single analog multiplier and five precision resistors, an output voltage (Ko) can be made to create a second- order polynomial. The circuit implements the quadratic shown. The input terminals of IC1 are connected to create a positive square term and present the Vr signal to the output with a 1-10-V scale factor....
Furnace Fuel Miser Circuit
A timer (LM555CN) and decode counter is used to generate duty cycles from 10% to 100% to control the time a heating system can operate. V2 is a decode counter that can be switched from 10% to 100% duty cycle. V3A and form a latch that drive Al, LED1, and V4. The triac TRI is used as an ac switch, in series with the thermostat that controls the...
Add-On Pulse Generator Circuit
This pulse generator can supplement a standalone pulse generator. Using a transistor and a 555 timer, pulse widths of 5 to 500 can be produced. The value of C3 is approximately found from the formula: C3 uF = 1.1 x10-5 T where T is the shortest pulse width (uS) desired in a 10:1 range (T should be greater than 5uS).
Precise One Shot Circuit
This approach uses a Hip-Hop, a shift register, and two gates (A). Before the one-shot pulse, the output of the NOR gate is 0. Consequently, the data input of the D-type flip-flop is equivalent to the trigger. When a trigger pulse is present, the flip-flop initiates the one-shot pulse, and the n-stage sliift register controls the pulse width,...
6.5Mhz Vfo Circuit
Fixed-value capacitors are disc ceramics. CI, C4, C5, C6, and C8 are NPO ceramic or polystyrene. C2 is a 25-pF ceramic trimmer and C3 is a 15- pF miniature air variable capacitor. The resistors are -W carbon film or composition. The RF chokes are miniature Mouser Electronics No. 43LR103 units. For LI, use 32 turns of #28 enamel wire on an...
Rf Signal Generator Circuit
This circuit uses a VFO operating from 15 to 18 MHz (Ul), which feeds a balanced mixer (U2). A fixed oscillator signal is mixed with this signal to generate an output from 0.4 to 33 MHz. FL1 and FL2 are low- and high-pass filters that are used to eliminate undesired mixer products.
Ham Band Vfo Circuit
This basic VFO for the 3- to 6-MHz range is coirimonly used in amateur applications, using a Colpitis circuit. For 5 to 5.5 MHz, C = C2 = 70 pF and for 3.5 to 4.0 MHz, use 1000 pF. C3 is typically 10 to 220 pF, depending on the frequency. C4, C5, and C6, together with C3, determine the frequency along with LI.
Highly Stable 60Hz Sine-Wave Source Circuit
A highly-stable 60-Hz sine wave can be delivered with this circuit, which offers a different and much simpler approach to gaining a stable amplitude.
Simple Sine-Wave Generator Circuit
A 555 timer operating in the astable mode generates the driving pulses and two 4518 dual BCD (binary coded decimal) counters provide the square waves. A TL081 op amp serves as an output buffer-amplifier, and potentiometers Rl and R2 are used in order to control the pulse`s frequency and amplitude, respectively. The output-frequency range can be...
Sine Wave Generator Circuit
In this circuit, a square wave is filtered by a high-order low-pass filter so that a -3-dB frequency will eliminate most harmonics of the waveform. As a result, the filter outputs a fundamental sine wave. This method is applied to generate a sine wave by using a switched- capacitor filter (MAX292) (see the figure). This circuit offers wide...
Pure Sine-Wave Generator Circuit
A TTL counter, an 8-channel analog multiplexer, and a fourth-order low-pass filter can generate 10- to 25-kHz sine waves with a THD better than -80 dB. The circuit cascades the two second-order, continuous-time Sallen-Key filters within ICS to implement the fourth-order low-pass filter. To operate the circuit, choose the filter`s cutoff...
Video Line Bar Generator Circuit
A 555 and a dual 556 timer generate a rudimentary video signal, as shown in the schematic. The first timer generates 4.7-8 synch pulses operating in the astable mode with a 64-8 period. The second timer generates a delay pulse, which triggers the third timer to generate a bar,
Sinusoidal 3Hz To 300Khz Vco Circuit
This circuit uses Analog Devices` AD639 universal trigonometric function generator to convert a triangle waveform, the basic waveform of the VCO itself, into a very low-distortion sine wave. By using the AD639 in its frequency tripler mode , the frequency range 3 Hz to 300 kHz is now covered. The circuit has been drawn here--so that the...
Vco Circuit Circuit
The output frequency of this simple low-cost active voltage-controlled oscillator circuit is based upon the inherent frequency dependent characteristics of our operational amplifier. The oscillator circuit shown uses a TL082 op amp. When power is applied, the circuit generates a sinusoidal wave.
The microprocessor-controlled oscillator has a 8159 to 1 frequency range covering 2 Hz to 20 kHz. An exponential, current output IC DAC functioning as a programmable current source alternately charges and discharges a capacitor between precisely-controlled upper and lower limits
Channell is wired as a conventional integrator, and channel2 as a voltage follower. When channel2 is switched on, the output will follow VJN and C will discharge to maintain 0 V across it. When channel! is then switched on, the output will initially be at the instantaneous value of VJN, and then will commence integrating towards the opposite...
Inexpensive Pulse Generator For Logic Troubleshooting
Built around a 555 timer IC, this pulse generator can be built into a probe for logic
Three-Decade 15Hz To 15Khz Wien-Bridge Oscillator
In this circuit, an LM741 op amp drives a Wien-bridge network using two zener diodes as
Pattern Generator For Radio Direction Finding Circuit
In order to display polar quantities (magnitude and direction of a received radio signal), a sine and cosine voltage proportional to an angle (antenna direction) is needed. In this case, a sine-cosine potentiometer coupled to a directional antenna and a sample of a voltage proportional to received signal is used to display
Adjustable Vfo Temperature Compensator Circuit
Use of a differential capacitor allows temperature compensation of LC circuit using an NFO and N1500 ceramic. C6 is a differential capacitor that has two stators and one common rotor. When one capacitance (stator) is maximum, the other is minimum.
Pulse Generator With Variable Duty Cycle Circuit
Using only one IC and six passive components, this pulse generator has a frequency range of 400 to 4000 Hz and an adjustable duty cycle of 1 to 99%. A threshold detector (ICA) and an integrator (ICB) generate a triangular waveform. A positive voltage at the output of ICA causes the output of ICB to become a negative-going ramp. When the output...
Crystal-controlled signal source
This general purpose signal source serves very well in signal-tracing applications. The output level is variable to more than 1 Vrms into a 50 O load. Almost any crystal in the 1 to 15 MHz range can be used. Ql forms a Colpitis oscillator with the output taken from the emitter. A capacitive voltage divider (across the 2.2 emitter resistor)...
High-frequency crystal oscillator
A high speed oscillator is possible by combining an MECL 10 crystal oscillator with an MECL III frequency doubler as shown. One section of the MC10101 is connected as a 100 MHz crystal oscillator with the crystal in series with the feedback loop. The LC tank circuit tunes the 100 MHz harmonic of the crystal and may be used to calibrate the...
The output of a video amplifier is differentiated before being fed to a Schottky comparator. The propagation delay is reduced to typically 10ns. The output pulse width is set by the value of C, lOOpf giving a pulse of about 90ns duration.
The circuit has both square-wave and triangle-wave output. The left section is similar in function to a comparator circuit that uses positive feedback for hysteresis. The inverting input is biased at one-half the Vcc voltage by resistors R4 and R5. The output is fed back to the non-inverting input of the first stage to control the frequency. The...
Monostable photocell circuit
A photocell circuit provides automatic threshold adjustment. Monostable action prevents undesired retriggering of the output. With only one op amp IC, the circuit offers: Automatic adjustment of its trigger level to accommodate various light sources, changes in ambient light and misalignments; A built-in monostable action to provide only a...
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
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