LM317 Voltage regulator

[jadrockinw]

I'm using an external power supply to provide 24vdc to a GPS circuit. I am also supplying the same 24vdc to an LM317 being used to reduce the voltage to 15vdc to drive a small fan and a LED(with limiting resistor). The GPS circuit is disconnected and the fan disconnected. During checkout the circuit appears to saturate the LM317 when the micro switch applying power to the LM317 is turned on. If the micro switch is left on or the LM317 is hardwired and the external power supply is turned on everything is fine. I have tried caps, snubber circuits and different switches but no luck. This circuit is setup exactly as the application notes show it.

Thanks John

 

[jbartos]

Suggestion: Visit

http://www.national.com/pf/LM/LM317.html#Datasheet

for the datasheet. The max current is 3.4A. If you exceed this then the circuit must have the lower load (smaller fan) or you need an extra LM317. You may also contact the "National Semiconductor" tech support for an alternate solution.

http://wwwd.national.com/feedback/

 

[jadrockinw]

It is not a current problem. This circuit works fine when hard wired. It is only when the circuits switch is added to the circuit, that everything goes haywire.
Also, with the switch in the circuit and switched to the "on" position, prior to turning on the external power supply. Then switching the external power supply, the circuits works fine.
It is only when the circuits switch is turned on first that there is a problem.

 

[jbartos]

Suggestion: Some limit switches have "positive contacts" without "bouncing." Does the limit switch have the positive contact? Contact Honeywell/General Electric Co. regarding this. Some systems accept "bouncing contacts" others do not.