Newest circuit diagrams
Metal Detector
A single chip metal detecor with a range of a few inches. This is useful for decting nails or screws in walls and floors, or for locating buried mains cable. Read more...
ECM Mic Preamplifier
A microphone amplifier that may be used with either Electret Condenser Microphone (ECM) inserts or dynamic inserts, made with discrete components. Read more...
Variable PSU 3-15v
A variable power supply with adjustable voltage and current outputs made with the L200 regulator. Read more...
Variable Power Supply Using Fixed Regulator
This is a similar power supply that I used to power my FM Transmitter. After suffering long problems with mains hum, this design using a pi filtered C-L-C approach. This circuit offers excellent ripple rejection. Read more...
Hot Water Level Indicator
A simple device to indicate various levels of hot water in a tank. Read more...
Bug Detector
This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable detector is to get its sensitivity just right; too much and it will respond to radio broadcasts, too little sensitivity and nothing will be heard. Read more...
Fridge door Alarm
Beeps if you leave open the door over 20 seconds 3V battery operation, simple circuitry Read more...
