8 Channel Button Debouncer

A simple 8 channel denounce circuit board. Wire your buttons (or relays) to a positive voltage, and bring them (along with a ground reference). The output of the board will be a nice clean transition from high to low (and vice versa)

The filtering circuit is a first order low pass filter that operates on the equation:

$$f_c=\frac{1}{2\pi{RC}}$$

Where $f_c$ is your desired cutoff frequency in Hz. A handy sage mathematics script was written to easily calculate and experiment with values for the 1st order filter:

var('R')
var('C')
var('f',latex_name='f_c')
f(R,C)=1/(2*pi*R*C)
solve(f(C=0.47*10^-6)==50,R)[0].rhs().n()

For this circuit specifically, the cutoff is designed to be 50 Hz. If noise issues persist, either raise $R$ or $C$ or both. Also it may be wise to tie your button output to ground using a pull down resistor (perhaps 10k). This will ensure that the capacitors can drain in the off state. This feature could be embedded into the board, but it wouldn't work if you were instead switching ground, so I decided to leave it in a more flexible state.

Recommendation for Future Work:

Future editions of this board could include the buttons directly on it! It would be great for digital logic experiments. Remove the terminals and instead add headers so it fits right in a breadboard!

Development Videos:

• 8 Channel Button Debouncer - Schematic Design
• 8 Channel Button Debouncer - Circuit Board Design