Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

4780 smoked a transformer
4780 smoked a transformer
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
Thread Tools Search this Thread
Old 28th July 2005, 03:10 AM   #1
asc is offline asc  United States
diyAudio Member
asc's Avatar
Join Date: Jul 2005
Location: Portland, OR
Default 4780 smoked a transformer

Well, I was beta tesing my newly assembled LM4780 circuit with a guitar and an 8 ohm speaker the transformer went up in smoke after about a minute. The first minute sounded really good, btw. The x-former was rated at +/- 24V (48V with CT) @ .63 amps. After that was rectified, it was about 38.2VDC without a load, on a snubberized PS kit board. The specs on the 4780 said 80V max, so I tried it with an 8 ohm speaker load and the transformer overheated. Quickly I hit my handy power strip switch and I think everything is still ok.

The question: Will I need 2 or more amps at 38V?

Has anyone had marvelous success feeding a 4780 (chipamp) board? And at what current/voltage did you supply it?

Also, I have two 8 ohm speakers that I could either make into 16 (series) or 4 (parallel). What would be the best scenario?

  Reply With Quote
Old 28th July 2005, 03:14 AM   #2
agent.5 is offline agent.5  United States
diyAudio Member
Join Date: Aug 2003
Location: San Francisco, CA

I think you want about 10A
  Reply With Quote
Old 28th July 2005, 05:00 AM   #3
Stocker is offline Stocker  United States
diyAudio Member
Join Date: Dec 2003
Location: Austin
To be more precise, and to be safe, you want at least as much rated current capacity as the electronics are rated to produce. If your amplifier datasheet says it can put out 3 amps, get at least a 3A rated transformer.

If you get one that is rated for at least 2-3 times the current (e.g., 10 amperes), then the voltage will tend to droop much less and you will have good things like "less clipping" and "punchy bass" and "non-smoking transformers" etc.

Jesus loves you.
  Reply With Quote


4780 smoked a transformerHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
PPI resistor smoked markw78 Car Audio 22 16th July 2009 07:39 PM
Transformer smoked Aidan135711 Parts 3 1st August 2008 09:34 PM
Smoked Yamaha M-50 eb5agv Solid State 3 10th May 2008 08:07 PM
Smoked resistors darkfenriz Parts 4 30th April 2006 07:09 PM

New To Site? Need Help?

All times are GMT. The time now is 05:10 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio