# Flip-Flop

Astable Flip-Flop Circuit PCB. 

![Astable_Flip-Flop_Circuit_2025-10-16_c3e_pcb.jpg](https://git.chaospott.de/catalyst/flipflop/src/branch/main/Astable_Flip-Flop_Circuit_2025-10-16_c3e_pcb.jpg)

Blinks, but also makes square waves. 

Sinus waves are required for producing radio frequency, the form of oscillation obtained here is not the one we want for making radio transmitters,
the project is nevertheless a good entry point into creating and understanding oscillators.

View the attached images or open in Fritzing SW from https://fritzing.org/ to view the schematics, inspect or modify the circuit.

Parts required to make the flip-flop circuit are: 2x LEDs; 2x 10 μF capacitors; 2x 470 Ohm resitors; 2x 100 kOhm resistors; 2x BC547 transistors;

you will also need print yourself or have the circuit board printed for you for a fee, for example by uploading the .fzz file to https://aisler.net/
Gerber Files are available.

Q1 and Q2 are the BC547 transitor. Alternatilvy the equivalent 2N2222A can be used, it has slightly more gain than the BC547. However, the 2N2222A will have to be mounted rotated 180 degrees as it's pin out is the other way round than that of the BC547.

The blinking interval is determined by the values of the two 100kOhm resistors and that of the two capacitors as per the formula: T = R x C

Example values: 100 kOhm x 10 μF = 1.0s; 10 kOhm x 10 μF = 0.1s; 100 kOhm x 1 μF = 0.1s;

you can choose LEDs of any color.

J1, J2, J3 are optional. Use to pick up the square waves and display on a oscilloscope. J3 is ground.

Fritzing has a breadoard view: the project can be made without a PCB.

This work is dedicated to the public domain.


