Latest Blog Posts - projects pack
- Signal Tracer and Injector CircuitDescription: A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an audio tracer. a single pole double throw sitch is used to switch between inject a...
- Electromagnetic Field Probe with Meter Output Circuiton Sep 23, 2013 in Tools MeasurementThis tester is designed to locate stray electromagnetic (EM) fields. It will easily detect both audio and RF signals up to frequencies of around 100kHz. Note, however that this circuit is NOT a metal detector, but will detect metal wiring if it condu...
- Voltage Comparator Switch Circuiton Sep 23, 2013 in Microcontroller Projects MicrocontrollerThis circuit will provide an indication whenever the input voltage differs from two defined limits, V1 and V2. The supply voltage, Vcc must be higher than the highest input voltage by at least 2 volts. One application here is to monitor a 12V car bat...
- Two Simple Crystal Test Circuiton Sep 23, 2013 in TesterDescription. Two simple test circuits to check operation of quartz crystals.In the first circuit, above the BC548 is wired as a colpitts oscillator, the frequency tuned by insertion of a crystal. A good crystal will create high frequency oscillations...
- PBS Switch Debouncing Circuiton Sep 23, 2013 in 555 Timer Project Circuits MicrocontrollerDescription: This circuit will remove the transient spikes and contact bounces from a non-latching push button switch.Using a 555 timer as a monostable circuit, it is easy to build a good switch debouncer circuit. There are many circuits for SPDT deb...
- 2 Transistor FM Voice Transmitter Circuiton Sep 23, 2013 in Radio (RF)Take care with transmitter circuits. It is illegal in most countries to operate radio transmitters without a license. Although only low power this circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres. Circuit Diag...
- Multi Wire Cable Tester Circuiton Sep 23, 2013 in TesterDescription 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...
- DC Motor Reversing Circuiton Sep 23, 2013 in motorDescription: A DC motor reversing circuit using non latching push button switches. Relays control forward, stop and reverse action, and the motor cannot be switched from forward to reverse unless the stop switch is pressed first. Except for the back...
- Water Activated Relay Circuiton Sep 21, 2013 in Microcontroller Projects MicrocontrollerThis circuit Marin has used two transistors wired as a high gain compound pair. Transistor T1 may be a 2N2222A and T2 a BC108. The current gain will be the product of each transistors beta, which will be a minimum of 140 x 110 or 15400. The power sup...
- Bench Amplifier CircuitDescription: A small 325mW amplifier with a voltage gain of 200 that can be used as a bench amplifier, signal tracer or used to amplify the output from personal radios, etc. the circuit is based on the National Semiconductor LM386 amplifier. In the d...
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