This blog post is about making an astable multivibrator from discrete transistors. This weekend I embarked on making a home-brew computer from discrete transistors. To test circuits like a JK flip-flop or SRAM, a clock is needed. In the spirit of keeping with an all discrete transistor computer, I used an astable multivibrator composed of two RTL NAND gates. I wanted to start with a very low frequency, so I targeted 10 seconds high, 10 low for the clock.