help needed with 12 volt fluid flow sensors and pulse generators

[garyd]

I'm afraid a lot of what you say is way over my head but the resistance measurement from the Red pin on the external cooler to the White pin is 12.14 and from Red to Yellow is 2.52 this is with the unit switched off and the multimeter set in the 20K range , if you need the measurements with the unit switched on ? let me know and i'll measure them for you .

 

[alec_t]

That points to there being a 2k2 pull-up resistor at the cooler input. I reckon you should be ok without the transistor circuit I suggested if you connect
1) red to Vcc of the generator,
2) yellow to OUT, and
3) both black and white to Gnd.

 

[KeepItSimpleStupid]

You could also try a series diode with the pulse generator output with the anode pointing to the contoller.

 

[garyd]

I have connected it all up as you suggested and it still went to alarm with the pulse generator displaying a solid LED so I tried adjusting one and then both of the pots but apart from the LED now rapidly flashing there was basically no change , I then tried moving the jumper to the next position along and somewhat surprisingly for me it now works with no alarm sounding at any stage , do you think we've cracked it ?

 

[alec_t]

Reckon we have. Not too surprising. The pulse rate presumably is now in the range the controller expects to see. Too high or too low a rate would indicate a sensor fault, excessive flow or inadequate flow and trip the alarm.

 

[garyd]

I have left the unit running for several hours now and given it a lot of on/off cycles and it has not gone to alarm even once so yes I think we are definately there , it only remains for me to thank you far more than I can say you have devoted a lot of time and effort to help someone you do not even know, live long and prosper is what I hope you do .

 

[KeepItSimpleStupid]

Did you use the transistor or the diode circuit?

 

[garyd]

Neither I simply wired up the PG as you said fiddled with the pots and then swapped the jumper and it's been working fine ever since .

 

[garyd]

Neither I simply wired up the PG as you said fiddled with the pots and then swapped the jumper and it's been working fine ever since .