I am not getting along with comparators

[Yossarian451]

I have used comparators a while back and now I am trying to build a thermostat and somehow after 3 comparatos I still have yet to get any kind of response from the stupid circuit. I have worked with IC's plenty before but I am either missing something or I really have bad luck. Seriously though, even just hooking up Vcc and ground and then putting one pin low one high the output just stis there. I just don't understand how I could have fried the lm339 and its not that hard of a concept, but I seem to have missed something. Anyone have any ideas what I could be doing wrong.

 

[PottedMeat]

You've probably already looked into this but is the output connected to Vcc through a resistor? LM339s are open collector outputs right? Without a pullup resistor the output transistor switches nothing.

Got a circuit diagram?

 

[TuxDave]

Link to chip plz

 

[jmcoreymv]

Originally posted by: PottedMeat

You've probably already looked into this but is the output connected to Vcc through a resistor? LM339s are open collector outputs right? Without a pullup resistor the output transistor switches nothing.

Got a circuit diagram?

Yea, the LM339 has an open collector output which needs to be tied to VCC through a pullup.

 

[Yossarian451]

I really was being stupid, I had a pullup, but alas I arbitrarily put one in and it happended to be something like 1M, so the voltage out was like .2, I looked at the typical application for one and saw it was 3k and now I fixed it. If only my thermistor would behave, I can't get it to stabilize for me to get good readings off for my calculations of the neccesary voltage divider for the pot. I will post schematics when done.