Things With Strings

I'm planning on building a bass drum module, and I will need a pulse generator to test it, so I knocked up a circuit based on a 555 timer in ASTABLE mode and put it in an Altoids™ tin. You can easily find a circuit for this just googling around. I drew one up in Kicad like this. As I wanted this to be a pulse generator for triggering a drum circuit, I wanted the frequency range to fall within a range that would be useful for music, which is calculated by a combination of R1, P1 and C1 in the circuit diagram above. There are plenty of on-line calculators that will help here. I used this one  http://www.ohmslawcalculator.com/555-astable-calculator  (P1=R2 in the calculation). I found that a combination of R1=3K3, P2=1M and C1 as 2µ2 gave the best range for my purposes (approximately 0.327Hz to 198.761Hz). I had a small piece of perfboard offcut that I tried to squeeze it onto, and here is the layout. For the output jack, I used a 3.5mm jack I salvaged from an old PC sou