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Electronics => Electronics => Topic started by: Warhawk87 on September 27, 2010, 04:05:42 PM

Title: Voltage regulator not regulating
Post by: Warhawk87 on September 27, 2010, 04:05:42 PM

Hey everyone,

I apparently blew out the voltage regulator on my duemilanove board so I built an external one... Two 100uF capacitors on the input and out of a 7805 regulator... Unfortunatly I'm still getting 12 volts from my multimeter...

Title: Re: Voltage regulator not regulating
Post by: galannthegreat on September 27, 2010, 05:53:11 PM

Show us how you have it wired in, maybe you may have did something wrong.

Title: Re: Voltage regulator not regulating
Post by: Warhawk87 on September 27, 2010, 07:02:39 PM

its positive battery terminal to capacitor to voltage regulator, middle pin goes to ground, other voltage regulator pin goes to other capacitor which goes to ground.  I dont know how to physicaly show it to you so thats the best I got...

Title: Re: Voltage regulator not regulating
Post by: waltr on September 27, 2010, 07:35:23 PM

Sounds like you have the regulator input and output pins reversed.
Recheck the pin-out on the data sheet and note if the view is from the bottom or the top. This has gotten me a few times.

Title: Re: Voltage regulator not regulating
Post by: knossos on September 27, 2010, 07:37:24 PM

Waltr beet me to it, hehe.  If that isnt your problem, can you take a picture and post it or sketch your schematic in paint or something?

Title: Re: Voltage regulator not regulating
Post by: Warhawk87 on September 27, 2010, 08:48:06 PM

If I put it in the wrong way would that have busted it? Because I thought of that too and switched it around but I still got nothing

Title: Re: Voltage regulator not regulating
Post by: galannthegreat on September 28, 2010, 01:56:45 AM

It could have, but most linear regulators a pretty resilient. But if so, it's a 50 cent part, so I wouldn't worry.