I recently aquired a rotary type flowmeter switch, as described here:
http://sales.goldmine-elec.com/prodinfo.asp?prodid=7052
I got it on sale for 9.95, but that sale is over. The description is not completely accurate, see this thread:
here for more details.
It has a rotor that feeds into a circuit board containing a relay that trips if the flow drops below a certain (user adjustable) minimum.
Just for coolness sake, I would like to be able to pick up a reading of what kind of flow I am getting when the relay isn't tripped. It needn't have a relation to any 'real' flow value, just a value to say how fast the rotor is spinning.
I am sure there must be a way to get a 'fan tach' type signal like that put out by a 3 wire fan which I could feed into a DigiDoc or otherwise unused mobo fan connector to tell me what it's doing. It might even be very easy, the circuit board has an undocumented, unused 2 pin connector sitting near the other outputs.
But before I go poking around with a scope, it would be nice to know what I'm looking for... I've seen something about the fan tach wire producing an intermittent connection to ground - is this right?
If so, does that mean the thing reading it is supplying a voltage? If so, what voltage and current?
Inquiring minds want to know...
Thanks,
Gooserider