Thanks everyone for your help! The circuit now works really well.
@gary350: Thanks for that link, I'll build that circuit in the future. What book is it from? It does look really good.
@Boncuk: Why do you use a smaller capacitance for this sort of circuit. Does it improve performance, just make the resistor values easier or just convention? Thanks very much.
@Boncuk: Why do you use a smaller capacitance for this sort of circuit. Does it improve performance, just make the resistor values easier or just convention? Thanks very much.
Small value cacpacitors are available with a tolerance of 2.5%, whereas electrolytic caps have 40%. Timing is more predictable with smaller value caps.
Thanks everyone for your help! The circuit now works really well.
@gary350: Thanks for that link, I'll build that circuit in the future. What book is it from? It does look really good.
@Boncuk: Why do you use a smaller capacitance for this sort of circuit. Does it improve performance, just make the resistor values easier or just convention? Thanks very much.
That circuit is from TTL Cookbook by Don Lancaster. They also have one calls CMOS Cookbook and others. They have some really good information oots of ICs and lots of circuits. The 556 is a dual package with two 555 times in the same IC package.
I made the experience that having two oscillator circuits made with a 556 (one at 180Hz and the other at 400Hz) the first one made an output frequency close to 180Hz and the second had an output frequency of ~2.5KHz. Even changing the timer cap to a much larger value didn't change the frequency.