Maybe someone in here knows. What could I use in place of a thermisitor to drop voltage to a certain voltage so it always stays there. I'm working with 5 volts and I want to get a reading of like 4.7volts. I've tried different resistence resistors, but even a 5 ohm resistor completly kills the voltage.

 

If I remember correctly, thermistor voltage is dependent on heat, and resister voltage is dependent on current. If you are looking for a constant voltage drop to 4.7 volts, you may need some sort of transformer.

Someone correct me if I'm wrong...

 

Your right a thermisitor is a varable resistor that changes with heat. Basically this is what i'm doing. I'm getting rid of the thermistor because I don't want the voltage to vary with heat I want it to stay at one voltage and stay there contantly. And I think your right about the resistor, I think it's working like a load device in my certain cituation where it's a low amperage circuit and putting a resistor basically just drops all voltage through it, obvoiously i need some sort of thing that will drop the voltage, but not create a load on the circuit. How does a transformer work, and how would i hook it up to two wires?

 

A transformer is an inducing device. You hook up 5 volts to one side of the transformer and it induces 4.7 into the otherside. I'd have to sit and do the math to figure it out. I'm not sure it would be right though. You may want to talk to an electrical engineer, I'm just an industrial... Sorry I can't be more help.

 

You can't use a transformer with DC. If you want to knock down DC voltage you need a voltage regulator. You need to determine what kind of current-handling capability you need, and pick the appropriate device. For example, an LM-317 is fine for lower current applications. Radio Shack stocks this kind of stuff.

 

ever consider a DC to Pulse-Width modulator? www.parts-express.com has them.

 

or what about something like this?

It will work at 4.5 volts... is that close enough?? if you dont want it in cigeratte lighter form, just pull it apart and use the "guts".

 

Thanks for all the help guys. My freind has a potentiometer at his house i'm going to try that, which is what I think albee was pointing towards.

 

:doh: Yup, I didn't even think of that. Did it work for you?

 

I'm sure it would work, but i've pretty much given up for the time being since ebay has failed me in bringing these #)($#)$(*#)($*#)($*)#(*$)(#*$)(#*)$(*#$)( ers to a stop.
Go figure money is money right. It's the american way. Take people for all their worth as long as you benifiet from it. **** american that's why we buy honda's that's all i got to say. I'm a pure bread white boy by the way so don't even think i'm a racist cuz i'll kill a white boy just as fast as a "minority" if it comes down to it.