Circuit Lake

This little instrument, named as Pico C, can be used to measure capacitances down to fractions of a picofarad. It built based on ATtiny2313 microcontroller. It has range: <1 pF to 2000 pF (guaranteed); 2500 pF possible and resolution: 0.1 pF. To read the result, this low cost C meter comes with 2 lines [...]

Crystal radio is the simplest type of radio receiver, and can be handmade with a few inexpensive parts, like an antenna wire, tuning coil of copper wire, crystal detector and earphones. It needs no battery or power source and runs on the power received from radio waves by a long wire antenna.

This easy to build PLL FM transmitter can deliver RF power output typically of 5 Watt. The project uses PIC16F627A to control PLL IC TSA5511 during FM Tuning process. PLL in-lock state status is displayed on LCD or you can check it on LED indicator (when LCD not connected).

Here is the most stable, smallest, and energy saving FM transmitter. It uses only single transistor oscillator, PN2222A. Other high frequency / low noise transistor like 2N2222A, BFxxx series, BC109B, C, and even well known BC238 could work as well. Key to a well functioning, low consumption circuit is to use a high hFE / [...]