Fowkc

If you're powering your device from the mains, another option is to divide down your 50/60Hz signal to get 1Hz. Not particularly accurate, as the mains frequency wavers quite a lot. If you assume a +/- 1Hz deviation, that could be 30 minutes off in a day! Of course, most of the time the deviation is a lot less than that. It's quite interesting to see what happens the the frequency based on demand: http://www.dynamicdemand.co.uk/grid.htm

Ah yes, that makes sense. Thanks. I was hoping not to need yet another op-amp, but ces't la vie...

Hello all, First time posting. I've got a fair bit of hobby electronics experience, but I'm running into a wall as far as this particular project is concerned. I'm using an LM331 Voltage-Frequency converter, set up as per this diagram from the datasheet: Only differences: my Vs is about 12V, and my input is 0 to 5v, not 0 to 10v. The trouble I'm having is that at low input voltages there is no frequency output at all (just 0v). Ideally I would like a few kHz at 0v. I can see that it's going to be something to do with bias current or the "optional offset adjust" bit, which doesn't seem to do anything in my circuit. I don't have a -Vs though, and I don't know what value of potentiometer would be best to use. Long story short, I'm stumpted. Can anyone render assistance? I'm aware I could just add a constant offset to the input voltage, but from what I can gather from the datasheet that shouldn't be necessary, as it quotes a 10Hz minimum frequency for the circuit I have.