Custom Silicon Solutions Programmable 555 timer
In my previous blog post,
How I Solved My 555 Timer IC Frequency and Built a 555 Guituner,
even though I tried several different combinations of resistors in series, I was unsuccessful in finding the correct combination of resistors to achieve the elusive 440Hz. I had to come up with a kludge. I inserted an adjustable resistor (potentiometer) and was able to turn the knob on the potentiometer to tune the circuit to 440Hz to my electronic keyboard.
The problem is mostly likely to do with the tolerance of the resistor. The resistors I used had gold bands and that means they have a tolerance…