Published:2009/6/24 2:23:00 Author:May
High gain op amp combines up to four individually controlled input signals. The dc power source should be well filtered (battery is ideal), and the circuit should be well shielded to prevent hum pickup. (View)
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Published:2009/6/24 2:22:00 Author:May
IC1a and b are biased into the linear regions by R3 and R4. (IC1 must be 4011A). Outputs from gates are combined by op amp IC2, which provides low impedance output. (View)
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Published:2009/6/24 2:33:00 Author:Jessie
ircuit uses a simple RC network to pro-duce an exceptionally shrill tone from a minia-ture speaker. With the parts values shown, the circuit oscillates at a frequency of 3.6 kHz and drives a miniature 2 1/2 speaker with ear-piercing volume. The output waveform is a square wave with a width of 150 pts, sloping rise and fall times, and a peak-to-peak amplitude of 4.2 volts (when powered by 9 volts). Current drain of the oscillator is 90 mA at 9 volts, and total power dissipation at this voltage is 0.81 watt, which is well below the 1.25 watts the 14-pin version will absorb (at room temperature) before shutting down. (View)
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Published:2009/6/24 2:33:00 Author:Jessie
With only a minor circuit change, the basic LM3909 oscillator configuration can be turned into a code-practice oscillator. (View)
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Published:2011/7/27 5:38:00 Author:Sue | Keyword: Division Circuit
The picture shows the division circuit composed of voltage-frequency converter and amplitude modulator. The input voltage V1 controls field effect tube 2N4222's inner resistance value through operational amplifier A1, so the oscillate frequency of the nonstable multivibrator will be changed.A2 is the amplitude modulator. After the input signal V2 is modulated, it will be output. Presume field effect tube's pinch-off voltage is Vp. If Vp=(1+R1/R2), then the relation between input and output is : Vo=-V2/V1. V1 and V2 are required to have a range of 0-10V. The output Vo is an average value which can be obtained through the filter. It can also be obtained by reading the damped voltmeter. (View)
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Published:2009/6/24 2:32:00 Author:Jessie
Using the 2N5457 JFET as a voltage vari-able resistor in the amplifier feedback loop, produces a low distortion, constant amplitude sine wave getting the amplifier loop gain just right. The LM103 zener diode provides the voltage reference for the peak sine wave amplitude. (View)
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Published:2009/6/24 2:21:00 Author:May
Two or more signals can be switched and/or mixed without annoying clicks by using FETs and a low input-impedance op amp circuit. (View)
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Published:2009/6/24 2:31:00 Author:Jessie
This circuit will provide both a sine and square wave output for frequencies from below 20 Hz to above 20 kHz. The frequency of oscillation is easily tuned by varying a single resistor. (View)
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Published:2009/6/24 2:31:00 Author:Jessie
The oscillator delivers a high-purity sinusoid with a stable frequency and amplitude. (View)
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Published:2009/6/24 2:20:00 Author:May
Three or more inputs with individual level controls feed into the base of Q1 that provides a voltage gain of 20. (View)
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Published:2009/6/24 2:31:00 Author:Jessie
A dc power-distribution system for a stable oscillator should use a separate voltage regulator just for the oscillator circuit. (View)
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Published:2009/6/24 2:30:00 Author:Jessie
This supply uses IC regulators to supply +5, +6, +9, and +12 volts regulated from a nominal 12-V supply. (View)
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Published:2009/6/24 2:30:00 Author:Jessie
Almost any transistor will work. R1 and C1 will vary the tone. (View)
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Published:2009/6/24 2:29:00 Author:Jessie
This identifier can be used to drive a hidden transmitter in a radio fox hunt activity, where the object is to locate a hidden transmitter. (View)
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Published:2009/6/24 2:19:00 Author:May
This keyer uses a PIC16C54 micro-controller to generate a Morse code message. The microcon-troller must be programmed to suit users call IC or desired message. (View)
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Published:2009/6/24 2:19:00 Author:May
This simple circuit can be used to combine stereo signals to produce a mnaural output. R1 and R2 isolate both circuits and R3 controls the level of the combined output signal. (View)
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Published:2009/6/24 2:17:00 Author:May
General purpose preamplifier/mixer accepts up to four inputs, has a gain of 1600, and provides bass and treble controls that can be varied ±10 dB at 100 kHz resectively. IC1 and IC2 = LM301A. (View)
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Published:2009/6/24 2:16:00 Author:May
The audio filter shown has a bandpass of 200 Hz centered on 700 Hz. Resistors are 1% tolerance and capacitors should be 5% tolerance. (View)
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Published:2009/6/24 2:13:00 Author:May
Four inputs can be mixed by duplicating the circuit to the left of C3 and using the fourth gate of IC1. Two gates are used in a touch-operated switching circuit that controls the voltage on the base of switching transistor Q2. Touching TP1 and TP2 alternately turns the circuit on and off. (View)
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Published:2009/6/24 2:12:00 Author:May
This panning circuit (short for panoramic control circuit) provides the ability to move the apparent position of one microphone's input between two output channels. This effect is oftern required in recording studio mixing consoles. Panning is how recording engineers manage to pick up your favorite pianist and float the sound over to the other side of the stage andback again. (View)
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