Any tips on how to include two power supplies safely and efficiently? - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 30th August 2010, 08:46 PM   #1
diyAudio Member
 
Join Date: Mar 2009
Default Any tips on how to include two power supplies safely and efficiently?

On a unit I'm planning I would like to have a battery available as well as an option for connecting a supply from the wall (probably using a rectified AC signal), any tips other for getting them to supply the same circuit without having to fiddle with switches etc? I was hoping there'd be a way of making sure the wall-supply didn't overpower the battery or maybe even recharge it if it's the right type
  Reply With Quote
Old 30th August 2010, 09:18 PM   #2
Xoc1 is offline Xoc1  United Kingdom
diyAudio Member
 
Xoc1's Avatar
 
Join Date: Nov 2008
Location: Devon UK
A simple way is to connect each supply via a diode. The supply with the highest voltage supplies the current.
  Reply With Quote
Old 30th August 2010, 11:37 PM   #3
dangus is offline dangus  Canada
diyAudio Member
 
Join Date: May 2004
Location: Vancouver Island
With a sealed lead-acid battery, you just have to choose a charging supply that current limits at something like C/5 or less (C being the AH rating of the battery), and a voltage limit of about 2.4 volts/cell. And make sure the charger doesn't load the battery when unplugged.

With nicads and the like, the proper way would be a smart charger like the venerable Temic (Telefunken) U2400B or a microcontroller that will stop charging when the battery is full by watching voltage and/or temperature. Otherwise, a trickle charging arrangement is invariably a compromise which tends to overcharge the battery. That may be OK for commercial products that only have to outlive the warranty period, but less attractive if you're the one buying replacement batteries.

There may be useful smart battery charger chips to be salvaged from scrapped laptops and cellphones. Or get something from Maxim like the MAX712 or MAX713:
NiCd/NiMH Battery Fast-Charge Controllers
Google Maxim nicad or nimh charger and you'll find projects with board layouts.
  Reply With Quote
Old 31st August 2010, 01:37 PM   #4
diyAudio Member
 
Join Date: Mar 2009
Good ideas, cheers! I'm tempted to use the diode trick but wouldn't voltage be knocked off? I need a 9v supply and I'm trying to keep the supplies to 9v for ease of availability.
Could I use a J-FET as a gate? It would be better to have the wall supply as the first priority, I was also considering a logic gate.
That battery chip-charger is a very good idea too, I'm saving that for a future project!
  Reply With Quote
Old 1st September 2010, 03:17 PM   #5
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Use Schottky diodes for low voltage drop.
  Reply With Quote
Old 2nd September 2010, 06:26 PM   #6
diyAudio Member
 
Join Date: Mar 2009
Yeah I think schottkys are the way to go for this especially with two in the same casing available for the task. Is forward current important or should I calculate how much power I need? My next project only has a few small-signal transistors in it and an LED
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Parallel a dual power supply or two power supplies? Thunau Power Supplies 12 16th February 2007 04:21 AM
Gb - Power Amp Power Supplies mhb Group Buys 6 22nd November 2006 07:59 PM
Help me with my Denon POA1500(schem include) ostie01 Solid State 5 1st July 2006 01:20 AM
ATX (computer) power supplies for power amp robmonk Solid State 29 12th February 2005 05:06 AM
Regulated Power Supplies for Low Power Amps PTL60 Solid State 18 6th February 2002 06:24 AM


New To Site? Need Help?

All times are GMT. The time now is 05:22 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2