Random circuits

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Mini High-Voltage Generator

Here’s a project that could be useful this summer on the beach, to stop anyone touching your things left on your beach towel while you’ve gone swimming; you might equally well use it at the office or workshop when you go back to work. In a very small space, and powered by simple primary cells or rechargeable batteries, the proposed circuit generates a low-energy, high voltage of the order of around 200 to 400 V, harmless to humans, of course, but still able to give a quite nasty ‘poke’ to anyone who touches it.... [read more]

Time Delay Relay II

When activated by pressing a button, this time delay relay will activate a load after a specified amount of time. This time is adjustable to whatever you want simply by changing the value of a resistor and/or capacitor. The current capacity of the circuit is only limited by what kind of relay you decide to use.... [read more]

Stereo Power Amplifier 4W-8W with TDA2005

This circuit [Fig.1] is a class AB stereo audio power amplifier designed by Quasar for quality hi-fi applications using a TDA2005 module. It is easy to construct and has a minimum of external components. The module has output current protection and thermal protection. This is circuit, which produces an excellent sound. The supply voltage required 9V-18V DC at 1 to 2 Amps. Maximum output power will only be obtained with a power supply of at least 2A at 15V DC, and using 2 Ohm speakers or 2 by 4 Ohm speakers in parallel. However approximately 4W/ch. can be obtained with only a 15V DC, 1A supply into 4ohm loads.... [read more]

Light/Dark Detector

This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.... [read more]

Portable Microphone Preamplifier

This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply.... [read more]

IR Remote Control Tester

IR Remote Control Tester... [read more]