loudspeaker protection and muting circuit trouble :( - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 21st March 2004, 02:52 AM   #1
diyAudio Member
Join Date: Aug 2002
Location: Farmington, CT
Send a message via AIM to Mattyo5
Question loudspeaker protection and muting circuit trouble :(

Ok, I built Rod Elliots Loudspeaker protection and muting circuitry and its not working properly.


i used a BD140, 2 mpsa42's and 1mpsa92 for the transistors, and the mpsa are wired backwards. ...and hence they are inserted backwards. The reason I used them is because my PS is +-70vdc...which is a little higher than Rod's recommended voltage. Ok, here's the problem. I have an LED helping me indicate power output to the relays. When I turn AC power on, nothing happens, relays don't flip. If I attach 70vdc to the AC input terminal, relays flip and STAY flipped (as opposed to only flipping for 2 seconds and flipping back). I haven't even tried the DC dectection yet, since AC doesn't seem to be working properly. since i have gotten the relays to flip somehow, i'm pretty sure the relay resistor is correct, but somewhere i put the wrong component in....though I kinda doubt it. Its a simple circuit. Can anyone have a look at it and let me know where my error might be? Thanks!

-Matthew K. Olson
  Reply With Quote
Old 21st March 2004, 03:18 AM   #2
diyAudio Member
Join Date: Aug 2002
Location: Farmington, CT
Send a message via AIM to Mattyo5
Ok, never mind. My trouble was that I was taking the AC from the line ac....instead of after the transformer at the bridge rectifier. Also, the circutry is a little backwards from how I imagined it, I thought that if DC was detected...the relays would flip from rest to switched. Instead, the relays flip from switched to rest position. so instead of me having my LED come on only when DC is detected....its on all the time and when DC is detected it goes off. Hmm. have to figure out something there. later!

-Matthew K. Olson
  Reply With Quote


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
Loudspeaker protection circuit space2000 Solid State 37 22nd January 2017 12:41 PM
HELP with kit: speaker protection and muting paulspencer Everything Else 0 7th September 2005 02:57 PM
Trouble with speaker protection circuit (Randy Slone's circuit) whalefat Solid State 3 13th April 2005 11:13 AM
DIY system setup - muting, de-thumping, spkr protection, remotes etc ... paulspencer Everything Else 5 6th January 2005 01:29 PM
muting circuit in a CD player jarthel Digital Source 3 9th May 2002 03:19 PM

New To Site? Need Help?

All times are GMT. The time now is 08:46 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2