Circuit Diagram

PRECISION_PEAK_VOLTAGE_DETECTOR_WITH_A_LONG_MEMORY_TIME

Published:2009/6/25 22:29:00 Author:Jessie

Circuit Notes The circuit has negative feedback only for positive signals. The inverting input can only get some feedback when diode Dl is forward biased and only occurs when the input is posi-tive. With a positive input signal, the output of the op amp rises until the inverting input signal reaches the same potential. In so doing, the capacitor C is also charged to this potential.When the input goes negative, the diode Dl becomes reverse biased, the voltage on the capacitor remains, being slowly discharged by the op amp input bias current of 10 pico amps.Thus the discharge of the capacitor is domin-antly controlled by the resistor R, giving a time constant of 10 seconds. Thus, the circuit de-tects the most positive peak voltage and remembers it.   (View)

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SUMMING_AMPLIFIER

Published:2009/6/25 22:23:00 Author:May

Uses RCA CA3018 four-transistor array as current-mirror triad with low 4 mpedance buffered output, to serve as high-performance summing amplifier. Mea-sured harmonic distortion is less than 170 at voltage gains up to 50 and with output swing of 10V P-P. High output impedance of 51 kil-ohms can be buffered by Q2 connected as emitter-follower.-W.G.Jung. Monolithic-Triad Cument Summer, EDNIEEE Magazine, July 1,1971,p52.   (View)

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FET_CASCODE_VIDEO

Published:2009/6/25 22:22:00 Author:May

Use of 2N5485 FETs gives very low input loading, with feedback reduced almostto zero，Bandwidth of amplifier is limited only by load resistance and capacitance．-″FET Databook,″ National Semiconductor,Santa Clara,CA,1977、p 6-26-6-36   (View)

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40_265_MHz_VMOS

Published:2009/6/25 22:21:00 Author:May

Wideband power amplifier using Siliconix Mospower FET in negative-feed-back circuit has flat gain within 0.5 dB over entire operational range of 40 to 265 MHz. Use 6 to 8 turns of No.30 on 1/2-W 1-megohm resistor for L1 (not commercially molded choke). T1 is 4 turns No.22 twisted- pair on Indiana General F625-902 toroid core. Avoid static charges until transistor is soldered into circuit.-E. Oxner, Mospower FET as a Broadband Amplifier, Ham Radlio, Dec.1976, p 32-35.   (View)

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TELEPHONE_CONTROLLED_TAPE_STARTER_TCTS

Published:2009/6/25 22:18:00 Author:May

This circuit converts a tape recorder into a completely automatic telephone conversation recording instrument that needs no external power source. Voltage at the switch terminals of tape recorder applied to a pair of Darlington-connected transistors, Q1 and Q2, will turn on and start the tape recorder. To turn the transistors off, and thereby stop the machine, apply a negative voltage to the base of Q1 from the phone line. When the telephone receiver is on the hook, there is typically about 50 volts dc across the phone divided across R1, R2, and R4 in such a way that the base of Q1 is sufficiently negative to keep the tape recorder off. When the phone's receiver is picked up, the voltage on the telephone line drops to about 5 volts, which leaves insufficient negative vol-tage on the base of Q1 to keep it cut off, so the tape recorder starts and begins to record.   (View)

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VHF_MODULATOR

Published:2009/6/25 22:17:00 Author:May

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TELEPHONE_RELAY

Published:2009/6/25 22:17:00 Author:May

Connected across the bell circuit of phone, this circuit closes a relay when the phone is ringing. Use the delay contacts to actuate any bell, siren, buzzer or lamp.   (View)

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TONE_DIAL_DECODER

Published:2009/6/25 22:16:00 Author:May

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TELEPHONE_OFF_HOOk_INDICATOR

Published:2009/6/25 22:27:00 Author:Jessie

The LED flickers when the phone is ringing or being dialed. It glows steadily when the phone is off the hook.   (View)

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4PULSE_WIDTH_MODULATOR

Published:2009/6/25 22:16:00 Author:May

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REMOTE_RING_EXTENDER_SWITCH

Published:2009/6/25 22:15:00 Author:May

The circuit can operate lamps and buzzers from the 120V, 60 Hz power line while main-taining positive isolation between the tele-phone line and the power line. Use of the iso-lated tab triac simplifies heat sinking by removing the constraint of isolating the triac heat sink from the chassis.   (View)

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3PULSE_WIDTH_MODULATOR

Published:2009/6/25 22:14:00 Author:May

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TONE_DIAL_SEQUENCE_DECODER

Published:2009/6/25 22:14:00 Author:May

The circuit takes active low inputs from a Touch Tone decoder and reacts to a proper sequence of digits. The proper sequence is determined by which Touch Tone digits the user connects to the sequence decoder inputs TT1, TT2, TT3, and TT4.   (View)

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TV_MODULATOR_USING_A_MOTOROLA_MC1374

Published:2009/6/25 22:13:00 Author:May

This one-chip modulator requires some outboard circuitry and a shielded box.   (View)

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TONE_DIAL_ENCODER

Published:2009/6/25 22:13:00 Author:May

Tone dial encoder with automatic PTT control uses the 555 timers.   (View)

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TONE_DIAL_GENERATOR

Published:2009/6/25 22:12:00 Author:May

The circuit requires a minimum of parts and uses a low cost standard 3.579545-MHz television color-burst crystal. The speaker can be eliminated and the output fed directly into the microphone input of a transmitter.   (View)

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AM_MODULATOR

Published:2009/6/25 22:11:00 Author:May

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2PULSE_WIDTH_MODULATOR

Published:2009/6/25 22:10:00 Author:May

The monostable circuit is triggered by a continuous input pulse train and the threshold voltage is modulated by a control signal. The resultant effect is a modulation of the output pulse width, as shown. A sine-wave modulation signal is illustrated, but any wave-shape could be used.   (View)

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RC_COUPLED_DIFFERENTIAL

Published:2009/6/25 22:10:00 Author:May

Input signal is applied to base of first differential amplifier and pushpull output is obtained from pins 8 and 10 for transfer to inputs of second IC. Feedback is transferred through RC combination back to pin 6 of first IC. Gain is varied with AGO voltage ap-plied to pin 2 of first IC. Gain is over 60 dB with flat response from 100 Hz to 100 kHz.-E.M.Noll, Linear IC Principles, Experiments, and Projects, Howard W. Sams, Indianapolis, IN, 1974, p 89-91.   (View)

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25_MHz_BANDWIDTH_LOW__NOISE

Published:2009/6/25 22:09:00 Author:May

RCA CA3018 fourtransistor array is connected as two pairs of common-emitter emitter-follower combinations, with two feedback loops providing high DC stabilhy. One path goes from emitter of Q3 back to input, and other goes from collector of Q4 to collector of Q1. Values of C1, C2, and C3 give low-frequency cutoff (3 dB down) of 800 Hz.Upper cutoff is 32 MHz.-E.M.Noll, Linear IC Principles, Experiments, and Projects, Howard W. Sams, Indianapolis, IN,1974, p 165-168 and 174.   (View)

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