DS1621 PC Thermometer Circuit

The following circuit is PC thermometer using DS1621. Feature : plug in any free PC com port, range of -20 to 125°C, Centigrade (°C) of Farenheit (°F) scale, basic accuracy and resolution 0.5°C, readable data log, sampling rate 1, 5, 30 or 60 seconds, basic accuracy and resolution 0.5°C, no external power supply required, easy to build, no calibration required. Component : 1N418 diode, Capacitor, LM2936Z, regulator, DB9 female, Zener diode, DS1621. [riccibitti.com]

Lithium Chargers

This is a lithium charger circuit. Feature : variable current 100mA-2A, simple circuitry, easy to build, inexpensive circuitry, +12V supply voltage. Component : LM741, variable resistor, resistor, zener diode, capacitor, L200. [flyelectric.ukgateway.net]

Balanced microphone preamp

The following circuit is a balanced microphone preamp. Feature : Simple circuitry, inexpensive, 60dB amplification, 12V supply voltage. Component : Resistor, transformer, potentiometer, ne5532, rectifier, 7812, 7912, fuse, capacitor, 7805, zener diode. [nomad.ee]