If you need to use an IR Remote control through the phone line check out this idea because of the signal transmitted by a remote control usually consists of serialized binary data, which is modulated at about 38KHz. The receiving device converts the modulated infrared light into electrical impulses, demodulates and processes them to obtain [...]

This is a power source that creates a DC voltage higher than the voltage feeding the it. It might be used to power your laptop (+18V) from a car battery (12V ~ 13.8V). It is built using very ordinary parts that should be readily available.source

This circuit is Undervoltage indicator.The green led light up whenever Vin is larger than approx. 12.5V, while a red led flashes when Vin is below 12.5V. The circuit draws current approx. 15mA.source

This is a frequency counter based on PIC16F84 for 100Hz-2.5GHz, using LCD 16 chara.x 2 lines ,TCXO 12.8MHz(1ppm ) and PIC16F84. The Voltage(0-510mV) of the input signal is also indicated on the LCD , therefore tuning of the coil can be conducted while checking the frequency. Furnished with IF offset-function, this can be applied for [...]

Here is an inexpensive way to get slow-moving analog data directly into a spreadsheet on your computer! A simple circuit connects to a serial port and a short Qbasic program gathers and saves 12 bit data to a file. A spreadsheet automatically retrieves the file and displays the data in real time.This simple interface can [...]