I set up a pulse circuit on a breadboard with a 555 timer. Input voltage is 5 V. My values are roughly:
- C = 100nf
- R1 = 1K
- R2 = 1M
I'm using this schematic:
This should produce 3 - 4 Hz at the output. When I power up the timer I get a frequency generated at about 150 Hz. Strangely when I disconnect the jumper from V+ (leaving it connected to pin 4), and touch the exposed end of the wire, the circuit works perfectly - outputting 3 - 4 Hz.
This is very weird to me. I tried some different resistor values and capacitors and it's the same result every time.