Circuit Diagram

1TV_MODULATOR

Published:2009/6/25 21:56:00 Author:May

The VHF frequency is generated by a tuned Hartley oscillator circuit. Resistors R2, R3, and R4 bias the transistor, with tapped inductor L1 and trimmercapacitor C1 forming the tank circuit. Adjusting C1 determines the frequdncy. Capacitor C2 provides positive feedback from the tank circuit to the emitter at Q1. Capacitor C4 provides an RF ground for the base of Q1. Bypass capacitor C5 and resistor R1 filter out the radio frequencies generated in the tank circuit to prevent radiation from the power-supply lines. The video signal enters the parallel combination of resistors R5 and R6; this combination closely matches the 75 ohm impedance of most video cables. Resistor R6 is a small screwdrtver-adjusted potentiometer that is used to control the video input level to mixer diodes D1 and D2.   (View)

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TWO_CHANNEL_SWITCH

Published:2009/6/25 21:56:00 Author:May

  (View)

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TV_MODULATOR

Published:2009/6/25 21:53:00 Author:May

The FM oscillator/modulator is a voltage-controlled oscillator, which exhibits a nearly linear output frequency versus input voltage characteristic for a wide deviation. It provides a good FM source with a few inexpensive external parts. It has a frequency range of 1.4 to 14 MHz and can typically produce a ±25 kHz modulated 4.5 MHz signal with about 0.6% total harmonic distortion.   (View)

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HIGH_FREQUENCY_SWITCH

Published:2009/6/25 21:53:00 Author:May

The 2N4391 provides a low ON resistance of 30 ohm and a high OFF impedance (＜0.2 pF) when off. With proper layout and an ideal switch, the performance stated above can be readily achieved.   (View)

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DIFFERENTIAL_ANALOG_SWITCH

Published:2009/6/25 21:52:00 Author:May

The NPD5566 monolithic dual is used in a differential multiplex application where Rd,coN) should be closely matched. Since Rd,coN) for the monolithic dual tracks at better than ±1% over wide temperature ranges (- 25℃ to +125℃), this makes it an unusual but ideal choice for an accurate multiplexer. This close tracking greatly reduces errors due to common-mode signals.   (View)

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TRIAC_ZERO_VOLTAGE_SWITCHING

Published:2009/6/25 21:55:00 Author:Jessie

The triac will be gated on at the start of the positive half cycle by current flow through the 3 μF capacitor as long as the C103 SCR is off. The load voltage then charges up the 1 μF capacitor so that the triac will again be ener-gized during the subsequent negative half cycle of line voltage. A selected gate triac is required because of the triggering mode.   (View)

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TV_MODULATOR

Published:2009/6/25 21:53:00 Author:Jessie

The FM oscillator/modulator is a voltage-controlled oscillator, which exhibits a nearly linear output frequency versus input voltage characteristic for a wide deviation. It provides a good FM source with a few inexpensive external parts. It has a frequency range of 1.4 to 14 MHz and can typically produce a ±25 kHz modulated 4.5 MHz signal with about 0.6% total harmonic distortion.   (View)

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HIGH_FREQUENCY_SWITCH

Published:2009/6/25 21:53:00 Author:Jessie

The 2N4391 provides a low ON resistance of 30 ohm and a high OFF impedance (＜0.2 pF) when off. With proper layout and an ideal switch, the performance stated above can be readily achieved.   (View)

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DIFFERENTIAL_ANALOG_SWITCH

Published:2009/6/25 21:52:00 Author:Jessie

The NPD5566 monolithic dual is used in a differential multiplex application where Rd,coN) should be closely matched. Since Rd,coN) for the monolithic dual tracks at better than ±1% over wide temperature ranges (- 25℃ to +125℃), this makes it an unusual but ideal choice for an accurate multiplexer. This close tracking greatly reduces errors due to common-mode signals.   (View)

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HIGH_TOGGLE_RATE_HIGH_FREQUENCY_ANALOG_SWITCH

Published:2009/6/25 21:49:00 Author:May

Commutator circuit provides low tmpedance gate drive to the PN4091 analog switch for both on and offdrive conditions．This circuit also approaches the ideal gate drive conditions for high frequency signal handling by providing a low ac impedance for off drive and high ac impedance for on drive to the PN4091   (View)

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VIDEO_ATTENUATOR

Published:2009/6/25 21:52:00 Author:Jessie

FETs in T attenuator provide optimum dynamic linear range for at-tenuation of video signals with ganged 1-meg-ohm pots. If complete turnoff is desired, atten-uatlon greater than 100 dB can be obtained at 10 MHz by using appropriate RF construction to minimize leakage. ON resistance of transistor (between drain and source) is less than 30 ohms.- FET Databook, National Semicon-ductor, Santa Clara, CA, 1977, p 6-26-6-36.   (View)

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50_MHz_POWER

Published:2009/6/25 21:49:00 Author:May

Developed for use with 50 MHz microtransistor crystal oscillator,using additional GE microtransistor for boosting RF output to about 75 mW，Article covers construction with microcomponents and gives other microtransistor circuits for low-power amateur tadiouse and possible bugging applications，-B.Hoisington、Introduction to″Microtransistors,″73 Magazit， Oct.1974,p 24-30.   (View)

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DTL_TTL_CONTROLLED_BUFFERED_ANALOG_SWITCH

Published:2009/6/25 21:48:00 Author:May

This analog switch uses the 2N4860 JFET for its 25 ohm ron and low leakage. The LM102 serves as a voltage buffer. This circuit can be adapted to a dual trace oscilloscope chopper. The DS7800 monolithic IC provides adequate switch drive controlled by DTL/TTL logic levels.   (View)

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PREAMP_F0R_O5_Hz_T0_2_MHz

Published:2009/6/25 21:50:00 Author:Jessie

Provides 11-dB gain over entire frequency range, with input impedance of 32 megohms. Q3 is GE-2 or HEP-52, and other transistors are SK3020 or HEP-53.-Circuits, 73Magazine, Jan. 1974, p 125.   (View)

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20_dB_VIDEO_LINE_DRIVER

Published:2009/6/25 21:50:00 Author:Jessie

RCA CA3100 wideband opamp and power transistor output stage together provide gain of 20 dB at video frequencies for driving 50-ohm line. Peak output voltage ranges from 8V at 1MHz to 1V at 8MHz Upper frequency limit for unity galn is about 38MHz．- Linear Integrated Circuits and MOS/FET's、″RCA Solid State Division,Somerville,NJ,1977,p 225-227   (View)

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CB_MODULATION_MONITOR

Published:2009/6/25 21:48:00 Author:May

Connect this circuit to a transceiver with a coaxial T connector in the transmission line. Key the transmitter (unmodulated), set S1 to CAL, and adjust R2 for a full scale reading. Return S1 to MOD position. The meter will read % modulation with 10% accuracy.   (View)

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HIGH_TOGGLE_RATE_HIGH_FREQUENCY_ANALOG_SWITCH

Published:2009/6/25 21:49:00 Author:Jessie

Commutator circuit provides low tmpedance gate drive to the PN4091 analog switch for both on and offdrive conditions．This circuit also approaches the ideal gate drive conditions for high frequency signal handling by providing a low ac impedance for off drive and high ac impedance for on drive to the PN4091   (View)

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STEREO_BALANCE_METER_1

Published:2009/6/25 21:47:00 Author:May

Play any stereo disc or tape and then set the amplifier to mono. Adjust left and right channel balance until meter M1 indicates zero; then the left and right output level are identical.   (View)

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50_MHz_POWER

Published:2009/6/25 21:49:00 Author:Jessie

Developed for use with 50 MHz microtransistor crystal oscillator,using additional GE microtransistor for boosting RF output to about 75 mW，Article covers construction with microcomponents and gives other microtransistor circuits for low-power amateur tadiouse and possible bugging applications，-B.Hoisington、Introduction to″Microtransistors,″73 Magazit， Oct.1974,p 24-30.   (View)

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DTL_TTL_CONTROLLED_BUFFERED_ANALOG_SWITCH

Published:2009/6/25 21:48:00 Author:Jessie

This analog switch uses the 2N4860 JFET for its 25 ohm ron and low leakage. The LM102 serves as a voltage buffer. This circuit can be adapted to a dual trace oscilloscope chopper. The DS7800 monolithic IC provides adequate switch drive controlled by DTL/TTL logic levels.   (View)

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