Published:2012/12/3 20:37:00 Author:muriel | Keyword: Square Wave Oscillator
A very basic square wave generator using a CMOS 4011 NAND gate. (View)
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Published:2012/12/3 20:36:00 Author:muriel | Keyword: EMF Probe , Meter
An electromagnetic field probe designed to detect changing electric and magnetic fields. The probe has a meter output and headphone socket as well. (View)
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Published:2012/12/3 20:36:00 Author:muriel | Keyword: Infra Red, Remote Control, Tester
A simple IR receiver to facilitate in testing of Infra Red Remote Control handsets. (View)
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Published:2012/12/3 20:35:00 Author:muriel | Keyword: 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. (View)
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Published:2012/12/3 20:34:00 Author:muriel | Keyword: 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. The transmitter and tone are adjustable so it is possible to build more than one unit and monitor several mouse traps simultaneously. (View)
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Published:2012/12/3 20:33:00 Author:muriel | Keyword: Solar Flasher
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Published:2012/12/3 20:33:00 Author:muriel | Keyword: Three Doorbells, Hearing Impaired
When the push switch is operated - the buzzer will sound and the LEDs will begin to flash. For the hearing members of the household - the buzzer acts as a regular doorbell. It also re-assures the visitor that the doorbell is working. When the push switch is released the buzzer will stop - but the LEDs will continue to flash. The length of time they will go on flashing is set by the values of R2 & C1. With the values shown in the diagram - the LEDs will flash for a further 30 seconds or so. If you make R2 a variable resistor, you can adjust the time period. If you want longer than 30 seconds - increase the value of C1 or R2. (View)
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Published:2012/12/3 20:32:00 Author:muriel | Keyword: Room Monitor
This circuit allows audio monitoring of a remote location and so doubles as a room monitor or baby alarm. It can be run from a 12 Volt battery or mains power supply as shown below. Interconnect uses 3 wires, so multi core cable can be used; alarm or telephone cable is suitable just leave any extra wires free. (View)
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Published:2012/12/3 20:31:00 Author:muriel | Keyword: Wart Zapper
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Published:2012/12/3 20:30:00 Author:muriel | Keyword: LED Flasher
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Published:2012/12/3 20:30:00 Author:muriel | Keyword: Ignition Coil Driver
This design uses a 555 timer and three 2n3055 switching transistors to provide a variable frequency, variable voltage input to an automotive ignition coil. Normal output is 25kV when run at 12v input and at the coil's resonant frequency (8kHz). Increasing the voltage output to about 50kV is possible if the input voltage is increased to 34v, however this risks burning out the switching transistors when the system is operated for an extended time.
Electrical Diagram:
Capacitors: rated at 50v
Resistors: 1/2w, 5% tolerance
Output frequency to the coil is controlled by VR1, output voltage is controlled by VR2.
V+ is connected to pin 3 on the 5v regulator. (View)
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Published:2012/12/3 20:28:00 Author:muriel | Keyword: Xenon Strobe
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Published:2012/12/3 20:28:00 Author:muriel | Keyword: Privacy Circuit
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Published:2012/12/3 20:27:00 Author:muriel | Keyword: Telephone In-Use Indicator
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Published:2012/12/3 20:26:00 Author:muriel | Keyword: LED Torch
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Published:2012/12/3 20:26:00 Author:muriel | Keyword: LED Flasher
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Published:2012/12/3 20:24:00 Author:muriel | Keyword: Monitor Splitter
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Published:2012/12/3 20:23:00 Author:muriel | Keyword: IR , Remote Volume, Controller
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Published:2012/12/3 20:22:00 Author:muriel | Keyword: Audio Indicator
This circuit can be used to remotely monitor a loudspeaker, alarm, or audio source for presence of an audio waveform. It can also be directly connected across loudspeaker terminals used as a peak indicator. (View)
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Published:2012/12/3 20:20:00 Author:muriel | Keyword: Decimal to BCD Convetor
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