Understanding the 7805, et al - Electronic Circuits Projects Diagrams Free

tab a · 29th January 2007, 07:45 PM

1. If a voltage regulator, like the 7805, has the correct input voltage, but incorrect voltages at all the other pins, is it by definition faulty? Or, can problems with caps or load cause this?

2. Am I correct in thinking some (power supply) voltage regulators handle only ac and some only dc? Do some do both?

Thanks.

evandude · 29th January 2007, 08:02 PM

I don't even understand what you're asking.

"at all other pins"? there are only three pins on a 7805 - normally one should be grounded, one input, and one output. If your input is correct and the ground pin is in fact grounded, and the output is not 5v, then the regulator MAY be faulty, but based on your confusing question it sounds like there could be any number of other issues that aren't the regulator's fault...

tab a · 29th January 2007, 08:25 PM

Whoops, sorry about that. I'm working with a L78MR05, with 5 pins.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Title	Starter	Forum	Replies	Latest
Need help about a 7805 regulator circuit !	Zarkabul	Electronic Projects Design/Ideas/Reviews	31	13th October 2008 05:35 PM
problem with 7805	mnoman	Electronic Projects Design/Ideas/Reviews	1	7th November 2006 10:09 PM
Did i kill my 7805?	Marks256	General Electronics Chat	21	25th August 2006 08:12 PM
Capacitor specs for use with 7805 regulator	loosewire	General Electronics Chat	2	11th January 2005 10:39 PM
Doubling 7805 current capacity?	charliez	General Electronics Chat	7	12th August 2004 04:58 AM

29th January 2007, 07:45 PM	(permalink)
tab a	Understanding the 7805, et al 1. If a voltage regulator, like the 7805, has the correct input voltage, but incorrect voltages at all the other pins, is it by definition faulty? Or, can problems with caps or load cause this? 2. Am I correct in thinking some (power supply) voltage regulators handle only ac and some only dc? Do some do both? Thanks.

29th January 2007, 08:02 PM	(permalink)
evandude	I don't even understand what you're asking. "at all other pins"? there are only three pins on a 7805 - normally one should be grounded, one input, and one output. If your input is correct and the ground pin is in fact grounded, and the output is not 5v, then the regulator MAY be faulty, but based on your confusing question it sounds like there could be any number of other issues that aren't the regulator's fault... __________________ EEgeek.net

29th January 2007, 08:25 PM	(permalink)
tab a	Whoops, sorry about that. I'm working with a L78MR05, with 5 pins.