Frequency to voltage conversion

Read the 2nd paragraph on page 7. You need to set up the chip to use dc.

It has a comparator that can be setup to be ground(or actually a bit above ground) and it says something about hysteresis in their too.

Optionally you could shift the voltage of the pulsed dc down by using a negative supply or possibily shifting the ic chip up. e.g., put a diode on the ground pin or use an active resistor(if the ic doesn't pull enough current for the diode to turn "on"). The output signals will all be shifted up of course but you can unshift them. At least this should work in theory ;)

You star. My only excuse (and I'd read that document *and* the AN-162 applications pdf) is that I'm a geologist by trade, and only picked up the physics I needed...

I now have the sensor and the chip talking to each other, with only one more problem to solve - it only works when I have a voltmeter between pin 1 and ground (I was measuring V(in) so I could balance the V(bias)). I have a feeling a M-ohm resistor will do the trick, but not sure why.

But I've stopped the night - I can't see the numbers on my capacitors anymore.

Simon

Well, try it and see ;) If it works then it works ;) I'm not sure what is going on though. Maybe adding just enough capacitance to the circuit or something else? It could be acting as a pulldown to ground which is needed if the input ends up floating for some reason.

A pull up resistor is needed most likely.

I will experiment. My sensor (and thus V(in) is working at +3v, my f-to-v IC at +9v. Would a pull-down on V(in) be better? Or would I be better off trying to run the sensor at +9v too?

Simon

Just to reply to myself. Everything is now working perfectly (I used a

The sensor is still on the +3v, with a bias (controlled by a variable pot) of half that. I actually feel like I almost understand what's going on in the circuit, and can make adjustments accordingly.

Thanks again for everyone's help.

Simon