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Electronic circuit : Two Simple Crystal Test Circuits

Two simple test circuits to check operation of quartz crystals.

Electronic circuit : Low Frequency Oscillator

A low frequency test oscillator for testing tone controls and experimenting.

Electronic circuit : Other EMF Probe Version

An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has switchable gain, a frequency response up to 400kHz and independent audio and meter monitoring.

Electronic circuit : Transistor Tester

A test circuit for BJT (Bipolar Junction Transistors). This circuit can measure both small signal hfe and DC current gain hFE of a low to medium power power transistor.

Electronic circuit : RF Probe

This RF probe can be used at High Frequency (HF) or Ultra High Frequency (UHF) on both 50 and 75 ohm coaxial cables.

Electronic circuit : Zener Diode Tester

I have teamed up with Magazine Mikro Elektronica for this project. Please visit their site. I am very grateful to Aleksandar Dakic for the kind translation into Serbian and Romanian languages.

Electronic circuit : EMF Probe with Meter

An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has a meter output and headphone socket as well.

Electronic circuit : Logic Probe

This logic probe uses a single CMOS 4001 IC and can display high, low and pulsing outputs.

Electronic circuit : Multi Wire Cable Tester

A multi wire cable tester with a separate LED for each wire. Will show open circuits, short circuits, reversals, earth faults, continuity and all with four IC's. Designed initially for my intercom, but can be used with alarm wiring, CAT 5 cables and more.

Electronic circuit : Connection Tester

A low resistance ( 0.25 - 4 ohm) continuity tester for checking soldered joints and connections.

Electronic circuit : Sine Wave Generator

A classic Wien Bridge oscillator using an Op-Amp covering a frequency range of 15 to 150kHz in four switched steps.

Electronic circuit : Electronic Mouse Trap

This circuit uses a conventional spring loaded mouse trap, available from hardware stores. However when a mouse is caught, the circuit triggers and transmits an interrupted tone on the commercial FM band to a nearby radio receiver.

Electronic circuit : Decimal to BCD Convetor

This circuit will provide an output in Binary Coded Decimal from any of the input switches. The input switches may be expanded to 16 switches, providing a Hexadecimal to BCD conversion.

Electronic circuit : Telephone In-Use Indicator

Please note that it is illegal to make a physical permanent connection to your telephone line in some countries (this includes the UK and Ireland). If building this circuit it is advisable to use a plugin cord so that the unit can be unplugged should a fault occur. If in doubt consult either your telephone or cable operator.

Electronic circuit : Combinational Conjuring Trick

The simple circuit of Fig.1 emulates a similar conjuring trick which sells for hundreds of Pounds. The trick seems to do the almost-impossible from an electronic point of view, let alone from the point of view of common sense.

Electronic circuit : High Quality Intercom

A very high quality intercom, which may also be used for room monitoring.

Electronic circuit : Infra Red Link

A basic Infra Red Link for audio communication for distances upto 3 metres.

Electronic circuit : Insect Repellent Circuit

Repell those repugnant insects from your Garden this Summer with this insect repellent circuit.

Electronic circuit : Quiz Circuit

I've had a few requests for a quiz circuit, so here is a 4 input design which can easily be modified.

Electronic circuit : Neon Desklamp

This circuit will power a 6 inch 4 Watt fluorescent tube off a 12 volt supply, consuming 300 mA. It may also be powered by a suitably rated universal AC/DC adapter. Advantages of the design are: good light, low power consumption, and readily available stock parts.
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