Home Community

Powering a device with Ac and Dc
Welcome, Guest. Please login or register.
April 16, 2014, 08:33:58 AM
Home Help Search Calendar Login Register
News: trade your components on this new board: "Components trade"

Advertisements
No New Posts
Today at 01:39:33 AM
in
Advertisements
by google

+  Electronics-Lab.com Community
|-+  Electronics Forums
| |-+  Power Electronics (Moderators: Gazza, Hero999)
| | |-+  Powering a device with Ac and Dc
« previous next »
Pages: [1] Print
Author Topic: Powering a device with Ac and Dc  (Read 1979 times)
xenobie
Newbie
*
Posts: 13


View Profile
« on: February 02, 2012, 10:59:52 AM »

Dear Friends,

I am building a device which requires 12VDC however it can either be powered by a car battery which is already 12V OR by 12VAC (or maybe 16VAC)

At first I thought it was simple because I can simply put a bridge rectifier and a 7812 and AC or DC won't effect my electronics. But now I am thinking about the voltage drop of the 7812 and the diodes. As far as I know, the 7812 needs at least 1.2V more in order to be able to regulate the voltage. So when using AC, there is no problem ... but with the car battery ... im clueless!!

Thanks
X
Logged

xenobie
Newbie
*
Posts: 13


View Profile
« Reply #1 on: February 20, 2012, 01:18:57 AM »

 Huh
Logged

Hero999
Global Moderator
Electronics God
*****
Posts: 2550



View Profile
« Reply #2 on: February 20, 2012, 05:28:13 AM »

You may get more help if you provided more information, such as what the device actually is?

You could put ORing diodes after the regulator and if you're cleaver you can configure it so it only looses a diode drop when running off the battery.

Oh and the LM7812 needs between 2V to 3V to regulate properly, 1.2V is much too low.
Logged

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question: if I know the answer, I'll be happy to help.

vera
Newbie
*
Posts: 1


View Profile Email
« Reply #3 on: April 26, 2012, 02:40:39 AM »

 Smiley
Logged

Pages: [1] Print 
« previous next »
Jump to:  

Advertisements
No New Posts
Today at 01:39:33 AM
in
Advertisements
by google


Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2013, Simple Machines Valid XHTML 1.0! Valid CSS!

 

 

Search Site | Advertising | Contact Us
Elektrotekno.com | Free Schematics Search Engine | Electronic Kits