Circuit Diagram

UHF_AMPLIFIER

Published:2009/6/18 1:55:00 Author:May

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SIMPLE_455_kHz_IF_AMPLIFIER

Published:2009/6/18 1:54:00 Author:May

The ZN416E can be configured as a simple 455-kHz IF amplifier. In this case, the drcuit's center frequency and bandwidth are set by RES1 (a Murata CSB455E ceramic resonator).   (View)

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20_W_1296_MHz_AMPLIFIER_MODULE

Published:2009/6/18 1:53:00 Author:May

Using a Mitsubishi M57762 amplifier module, this amplifier delivers 20-W output on 1296 MHz. A single 12-V nominal power supply can be used.   (View)

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RECEIVER_SCANNER_PREAMP_USING_MAR_1_MMIC

Published:2009/6/18 1:50:00 Author:May

The low-cost Mini-Circuits MAR-X series of chips offer the RF builder a real advantage, with their inherent 50-Ω input and output impedances (needed for RF systems). An MAR-l-based re-ceiver/scanner preamplifier is shown. C1 and C2 are chip capacitors. Use 0.01 μF for HF, 0.001 for VHF, and 100 pF for above 100 MHz, depending on the low-frequency limit that you desire. C3 can be a ceramic disc of 0.01 μF or 0.001 μF, de-pending on frequency range. L1 is an RF choke that is suitable for the frequency range that you desire (0.1 to 10 μH).   (View)

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2_METER_FET_POWER_AMPLIFIER_FOR_HTs

Published:2009/6/18 1:48:00 Author:May

Using a power MOSFET, this amplifier can boast a 2-W handie-talkie power level to around 10 W on 2 meters. A transmission-line RE switch is used for T/R switching.   (View)

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10_W_10_METER_LINEAR_AMPLIFIER

Published:2009/6/18 1:45:00 Author:May

This linear amplifier delivers 10-W PEP output with 1.25-W drive on 10 m. T1, T2, and T3 are 10 turns of bifilar windings on an FT-50-43 toroidal core. The transformers are broadband. Filters for other bands, if desired, are shown.   (View)

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TV_SOUND_SYSTEM

Published:2009/6/18 1:43:00 Author:May

An LM2808 performs IF amplification of the 4.5-MHz sound subcarrier, limiting, detection, and audio amplification. If the center frequency must be changed, then change L1/C4. Audio out-put is 0.5 W. R3 is the volume control.   (View)

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WIDEBAND_POWER_AMPLIFIER

Published:2009/6/18 1:43:00 Author:May

Using TRW P/N CA-815H, a 17-dB gain am-plifier that delivers 100 mW over 10 to 1000 MHz can be constructed. The CA-2870 will yield 0.4 W with 34-dB gain from 20 to 400 MHz.   (View)

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20_W_450_MHz_AMPLIFIER

Published:2009/6/18 1:41:00 Author:May

Delivering 20-W output, this amplifier has a gain of 21 dB at 450 MHz. A 12-V supply powers this circuit.   (View)

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30_MHz_AMPLIFIER

Published:2009/6/18 1:40:00 Author:May

Using a CLC406 op amp, this video amplifier has a voltage gain of +2 and is flat to 30 MHz. The circuit should be useable in video switching and interfacing applications.   (View)

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MINIATURE_WIDEBAND_AMPLIFIER

Published:2009/6/17 23:39:00 Author:May

Except for the coupling and decoupling capacitors, IC1 is a complete wideband amplifier that has a fixed gain of 20 dB to 450 MHz. No external compensation is required.   (View)

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70_MHz_RF_POWER_AMPLIFIER

Published:2009/6/17 23:38:00 Author:May

The SD1143 transistor provides a gain of about 14 dB in this circuit. It uses the fact that a 175-MHz device has a much higher gain when used at lower frequencies. The amplifier was originally de-signed to be used with a transverter. The output is 8 to 10 W for a 300- to 500-mW input.   (View)

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BROADCAST_BAND_RF_AMPLIFIER

Published:2009/6/17 23:36:00 Author:May

The circuit has a frequency response that ranges from lO0 Hz to 3 MHz; the gain is about 30 dB. Field-effect transistor Q1 is configured in the common-source self-biased mode; optional resistor R1 allows you to set the input impedance to any desired value. Commonly, it will be 50 Ω. The signal is then direct-coupled to Q2, a common-base circuit that isolates the input and output stages and pro-vides the amplifier's exceptional stability. Last, Q3 functions as an emitter-follower, to provide low output impedance (about 50 Ω). If you need higher output impedance, include resistor R8. It will af-fect impedance according to this formula:R8≈ROUT - 50. Otherwise, connect output capacitor C4 directly to the emitter of Q3.   (View)

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MOTORCYCLE_ALARM

Published:2009/6/17 23:34:00 Author:May

A dual tinter is used to generate a long pulse, which gates a second timer, producing a square wave (nonsymmetrical) and controls the on/off time of the hom. Siren operation can be selected with a jumper. In this case, the output of Q1 will be continuously on and not cycled. Sensor S1 is a row of adjacent circuit board traces with a stainless steel ball bearing laying on them. Any movement causes momentary shorting and opening of the circuit, triggering U1-a.   (View)

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CAR_ALARM_DECOY

Published:2009/6/17 23:32:00 Author:May

The device will simulate the presence of a burglar alarm in automobiles or homes. Mount RI where daylight can fall on it. During darkness, LED1 flashes, making potential intruders think an alarm system is installed.   (View)

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FLASHING_BRAKE_LIGHT_FOR_MOTORCYCLES

Published:2009/6/17 23:31:00 Author:May

When brake-light switch 51 is closed, power is applied to UI and U2. Two inverters of U2, a 4049 hex inverting buffer, are connected in a low-frequency oscillator circuit that feeds clock pulses into UI, a 4017 decade counter/divider. Outputs 0, 2, 4, 6, and 8 of U1 are coupled to the gate of Ql through a 1N914 diode. As the 4017 counts down, it turns the brake light on and offfour times and then leaves it on until the brake switch is released. The on/off rate can be set by potentiometer R2; for best results, the on/off rate should be set so that it is rapid.   (View)

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AUTO_SECURITY_SYSTEM_RECEIVER

Published:2009/6/17 23:28:00 Author:May

This receiver is a superheterodyne type tuned to 49 MHz. U2 is a mixer, followed by a 10.7-MHz filter and two-stage IF (U3, U4) and detector. The encoded received RE pulse signal from the an-tenna produces detected pulse from the MC1330P. These pulses are arrtplified by U5 and fed to de-coder IC U6, and MC1450278. Two channels are available at the output, which drives K1 and K2.   (View)

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HOME_SECURITY_SYSTEM

Published:2009/6/17 23:25:00 Author:May

At the heart of the main-control unit is U16, Zilog's Z8-8-bit microcontroller, which receives its program instruction from U17, a 27C64 8K x 8 EPROM. The home security system in its most basic form, features eight individual protection zones, adjustable entry and exit delays, a panic switch (for emergency situations), automatic system reset, support for an auto-dialer (which, in case of emergency, dials pre-programmed telephone numbers), it's X-10 compatible (allowing it to control house lights and ap-pliances), has a backup battery (to keep the system on-line during a power failure), and there is also an optional zone-status panel that is used to individually show the condition of each protection zone.This system's power supply provides 12 Vdc for the sirens and digital keypad, and 5 Vdc for the on-board electronics, while also providing a constant 12-V output that's used to charge the backup-battery.   (View)

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LOW_NOSIE_GASFET_PREAMP_FOR_435_MHz

Published:2009/6/17 23:21:00 Author:May

This circuit is a low-noise preamplifier for the 435-MHz amateur satellite frequencies. The cir-cuit uses a Mitsubishi MGF1302. A 28-Vdc source is shown, although by changing the 400-Ω 5-W re-sistor lower voltages can be used.   (View)

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AUTO_SECURITY_SYSTEM_TRANSMITTER

Published:2009/6/17 23:20:00 Author:May

This transmitter operates at 49 MHz and uses an M145026 programmable digital encoder to generate a unique digital code, depending on the positions of S2 and S3, to control ignition and lights or horn. Q1 is the oscillator, Q2 the power amplifier. The antenna is a 36-inch whip or wire antenna.   (View)

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