thermistors

[alwaink]

I'm looking for a cheap current limiting device that will cap the current at 25mA from the 120V wall plug. I read that a PTC thermistor would do what I'm looking for.

Has anyone dealt with thermistors? I guess I just need to look for one that allows normal operating current at 25mA, and solder the wires with a thermistor to make it in series.

 

[itsmoked]

Yes it is a series device just like a fuse. I would recommend you google for info and look at the various manufacture's application notes as they are non trivial to specify. You can screw up the application easily.

They have a peak voltage they can be used at.
They have a maximum fault current limitation.
They have a hold in current.
They have a trip current.
They have a current/time chart.
All these points need to be understood to correctly apply them.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com