Electronic Circuits for the Hobbyist, by VA3AVR Circuits for the Hobbyist by VA3AVR Tony's Message Forum Ask your questions here. Someone may answer them. Relays - Sound Activated Active Power Zener Relays - Transistor Boosted Active Antenna for AM-FM-SW Relays - Delayed Turn-on Active Antenna for HF-VHF-UHF Relays - Automatic Turn-off Active FM Antenna Amplifier Relays - Long Duration Aviation Band Receiver 2SC2570 Pin- Relays - Long Duration--1 to 100 min out, 12-17-2004 Relays - Long Duration--1 min to 20 hrs Alternating On-Off Switch Relays - Self Latching Audio Booster with 1 Transistor RF Transmitter, light sensing Audio Pre-Amplifier #1 RJ45 Cable Tester Modified version (Bruce Automatic 9-Volt NiCad Battery Charger Auto-Fan, automatic temperature control Marcus) ScanMate Your (Radio) scanner buddy! Basic IC MonoStable Multivibrator Simplest R/C Circuit Basic RF Oscillator #1 Simplest RF Transmitter Basic LM3909 Led Flasher Simple Transistor Audio PreAmplifier Battery Monitor for 12V Lead-Acid Single IC Audio Preamplifier Battery Tester for 1.5 & 9V Single Cell Sealed Lead Acid Charger - by Battery (NiCad) Rejuvenator Bench Top Power Supply, Part 1 Søren Solar Cell NiCad Charger Bench Top Power Supply, Part 2 Solid State Relay Bench Top Power Supply, Part 3 Stun Gun circuits on Chemelec's site Bench Top Power Supply, Part 4 Pics Third Brake Light Pulser Bench Top Power Supply, Auto-Fan Touch Activated Alarm System Bicycle Light with charger (soon) Birdie Doorbell Ringer Touch Switch using Transistors Broadcast-Band RF Amplifier Two-Tone Trainhorn 'Bug' Detector with Beep Universal Flasher Circuit Variable Power Supply, 1 - 30V @ 1.5A Car Back-up Alarm Wailing Alarm Car Converter for 12V to 9V Water-level Sensing and Control Car NiCad Charger Waterpump Safety Guard for Fish-pond Christmas Lights Tester Weller WLC100 Electronic Soldering Station Clock Generator Continuity Tester, Low-Voltage Wireless Microphone Continuity Tester, Smart Xmas Lights Tester Continuity Tester, Latching Zap Adapter Cut Phone Line Detector 1.5V Tracking Transmitter Dark/Light Activated Relay 4-Transistor Tracking Transmitter Dazer 7.2V Field Charger (.pdf file) DC Motor Reversing Circuit 9-V Stabilized Powersupply DC Motor Control Circuit 9 to 9 pin (Female) Nullmodem Cable DSL Filter (phone-line) 12V to 9V with a LM317 Amp Booster added Dual 12V Power Supply 30-Meter QRP Transmitter for Morse Code Fluid-Level Detector 555 DC-AC Inverter Fox & Hound, wire tracer 555 Timer IC Tester Gadgets for Radio Control Page 555 Go No/Go Tester More advanced Gel Cell Charger, I Electronic Symbols Template - Paint Shop Pro 10-27-2004 Gel Cell Charger, II Headlight Alarm Heat Sensor -- OFF-LINE (performance problems) Lantern Flasher/Dimmer 555 Timer/Oscillator Led Flasher, 2 transistor 741 Op-Amp Leds Flasher, alternately Capacitors Added Fig.3b, 10-27-2004 LED Pilot Light (AC or DC) Electronic Template Light Sensor With Hysteresis MosFet Test Logic Probe(1), with pulse, TTL/CMOS Piezo Education/Tutorial Logic Probe(2), with pulse, TTL/CMOS PLL Logic Probe(3), Audible, TTL/CMOS Resistor Color Code Tutorial Spelling, 8-05- Micro-Spy with FET's 2004 Micro-Spy with USW SCR Tester Micro-Spy with TTL Triac Test Miniature FM Transmitter #1 UJT Test Miniature FM Transmitter #2 Coils Miniature FM Transmitter #3 Integrated Circuits Miniature FM Transmitter #4 Make Your Own Shunts Mini-Drill variable Powersupply Relays, Relay Drivers, Solid-State Missing Pulse Detector (Basic) Morse Code Practice Keyer, I "Green" means on-line, "Red" means off-line Morse Code Practice Keyer, II Motor Accu Lader (Dutch language) Motorcycle Battery Charger Bookmark this valuable page with 'Ctrl-D'. No-Hassle Third Brake Light Power Supply Converted from a PC (link) Practical Intercom Pulse Timer, 555 Pulse Width modulator, 555 Pulse Width modulator, 4093 Radio Shack Special - Transmitters by Patrick Cambre Just in case you're gonna ask: All drawings are created with Paint Shop Pro Circuits Archive - Older circuits. Most are working, some are not. Could be still useful. Tony's Data Sheets - Data Sheet for common Semiconductors Data Sheets Archive - Link to tons of data sheets. Radio Shack Partnumbers - Most common order numbers for my circuits Resistor Value Calculator - By Danny Goodman, AE9F Tandy Corporation - European/Australian counterpart of Radio Shack Transistor 'SM' marking codes by Philips TUP/TUN/DUS/DUG European transistor replacement system PN100/200 - Data Sheets for the PN100 and PN200 LF13741 - Monolitic JFET Input OpAmp Data Sheet Toroids, RF/EMI Cores - Variety of commonly used toroids, colors, etc. Guelph Amateur Radio Club - GARC--Official Homepage Jonathan's Electronics Message Forum - More help if you need it! Other Interesting Links - Links to other interesting and informative Electronics Websites. November 1, 2004 DISCLAIMER: I take no responsibility whatsoever for the use and/or implementation thereof, or the misuse leading to damage to equipment, property, or life, caused by the above circuits. Check with local, provincial and federal laws before operating some of these devices. You may also check your life insurance and/or the fact if they cover death by electrocution if you intend to play with Micro-wave ovens and other possible lethal HV devices. Safety is a primary concern when working with high power circuits or con/inverters. Play it safe! Copyright © 1995, Tony van Roon (VA3AVR). ALL RIGHTS RESERVED. Last Updated December 17, 2004 http://www.uoguelph.ca/~antoon/circ/circuits.htm [1/2/05 12:23:36 PM] Alternating ON-OFF Switch Back to Circuits page Page Copyright © 1995 -- Tony van Roon http://www.uoguelph.ca/~antoon/circ/pwrzener.html [1/2/05 12:23:37 PM] AM-FM-SW Active Antenna Active Antenna for AM/FM/SW: This simple little circuit can be used for AM, FM, and Shortwave(SW). On the shortwave band this active antenna is comparable to a 20 to 30 foot wire antenna. It is further more designed to be used on receivers that use untuned wire antennas, such as inexpensive units and car radios. L1 can be selected for the application. A 470µH coil works on lower frequencies and lie in AM, for shortwave try a 20µH coil. This unit can be powered by a 9 volt alkaline battery. If a power supply is used, bypass the power supply with a 0.04µF capacitor to prevent noise pickup. The antenna used on this circuit is a standard 18-inch telescoping type, but a thick piece of copper, bus-bar, or piano wire will also work fine. The heart of this circuit is Q1, a JFET-N-Channel, UHF/VHF amplifier in a TO-92 case. It can be replaced with an NTE451. Output is taken from jack J1 and run to the input on the receiver. Source: "Popular Electronics" magazine, July 1989 issue. Copyright © Gernsback Publications, Inc. 1989. (Gernsback no longer in business). Back to Circuits page Copyright © 2003 - Tony van Roon http://www.uoguelph.ca/~antoon/circ/activant.html [1/2/05 12:23:38 PM] Active Antenna AA-7 HF/VHF/UHF, 3-3000MHz, Antenna booster Active Antenna AA-7 HF/VHF/UHF, 3 to 3000 MHz By Fred Blechman "Lift those hard-to-hear signals out of the mud with this handy receiver accessory." If you have a shortwave or high-frequency receiver or scanner that is struggling to capture signals with a short, whip antenna, and you'd like the kind of performance that a 60-foot longwire antenna can provide but lack the space to put one up, consider building the AA-7 HF/VHF/UHF Active Antenna described in this article. The AA-7 is a relatively simple antenna that is designed to amplify signals from 3 to 3000 MegaHertz, including three recognized ranges: 3-30Mhz high-frequency (HF) signals; 3-300Mhz very- high frequency (VHF) signals; 300-3000MHz ultra-high (UHF) frequency signals. Those bands are typically occupied by shortwave, ham, government, and commercial radio signals. Active Antennas: In its simplest form, an active antenna uses a small whip antenna that feeds incoming RF to a preamplifier, whose output is then connected to the antenna input of a receiver. Unless specifically designed otherwise, all active antennas are intended for receive-only operation, and thus should not be used with transceivers; transmitting into an active antenna will probably destroy its active components. A well designed broadband active antenna consider field strength of the desired signal (measured in microvolts per meter of antenna length), atmospheric and other noise, diameter of the antenna, radiation resistance, and antenna reactance at various frequencies, plus the efficiency and noise figure of the amplifier circuit itself. Circuit Description: Fig. 1 shows the schematic diagram of the AA-7, which contains only two active elements; Q1 (an MFE201 N-Channel dual-gate MOSFET) and Q2 (a 2SC2570 NPN VHF silicon transistor). Those transistors provide the basis of two independent, switchable RF pre-amplifiers. Two double-pole double-throw (DPDT) switches play a major role in this operation of the AA-7. Switch S1 is used to select one of the two preamplifier circuits (either HF or VHF/UHF). Switch 2 is used to turn off the power to the circuit, while coupling the incoming RF directly to the input of the receiver. That gives the receiver non-amplified access to the auxiliary antenna jack, at J1, as well as the on-board telescoping whip antenna. With switch S2 in its power-on position, the input and ouput jacks are disconnected and B1 (a 9 volt battery) is connected to the circuit. With switch S1 in the position shown in the schematic, incoming RF is directed to the HF preamp circuit built around Q1 (an MFE201 N-Channel dual-gate MOSFET). The HF preamp operates with an exceptionally low noise level, and is ideal for copying weak CW and singe-side band signals.