Discrete protection circuits - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

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
Reply
 
Thread Tools Search this Thread
Old 24th February 2004, 07:43 AM   #1
diyAudio Member
 
metal's Avatar
 
Join Date: Jan 2004
Default Discrete protection circuits

Hi everybody

I have started this thread with a circuit that I still dont know how its working,thought people dealing with solid state and discrete transistors may help,looking to the internal circuitry of the STK4040V may help you people.

What I want to know,how is T5 supposed to work as the protection element.That will activate the latch composed of T3 and T4,hence T1 will work and turn off the internal current mirror in the STK4040V.

Now,does any body can explain how is T5 working by some theoritical and mathematical basis,and is there any other circuits that might do the same job.

BR
Attached Images
File Type: gif muite and protection.gif (33.8 KB, 425 views)
  Reply With Quote
Old 24th February 2004, 08:34 AM   #2
diyAudio Member
 
Join Date: Aug 2003
Location: Prague,Czech Republic
It is not protectin circuit, it is probably " automute " , when amps are switch off. Protection circuity must have output relay.
  Reply With Quote
Old 24th February 2004, 09:00 AM   #3
diyAudio Member
 
runebivrin's Avatar
 
Join Date: Jul 2003
Location: Huddinge, Sweden
Send a message via MSN to runebivrin
When the voltage across the 0.22ohm resistor reaches a critical level for long enough, the cap across T5:s BE will have time to charge to 0.7 volts, and then the latch is triggered. The time constant of 220 ohms and 3.3uF is 0.73 ms, so with 1 volt across the 0.22 ohm resistor the protection will kick in in approximately that time frame. 1 volt across 0.22 ohm is 4.55 amps, so the circuit is short circuit protected to a voltage somewhere in that region.

A point to note is that it only measures current in one direction, so it's hardly fool proof.

Rune
__________________
Do wizards use spell checkers?
  Reply With Quote
Old 24th February 2004, 09:51 AM   #4
diyAudio Member
 
metal's Avatar
 
Join Date: Jan 2004
Default Thank you for replies

Ok runebivrin,I already know that this circuit works in the -ve direction only,then how can I design a circuit that acts on both the +ve and -ve directions,but I think its fool proof too.

Can any one suggest another protection circuit for such ICs,so one can use them with any audio power IC as he wants,and determine the current at which this circuit will work.

BR
  Reply With Quote
Old 24th February 2004, 11:36 AM   #5
diyAudio Member
 
runebivrin's Avatar
 
Join Date: Jul 2003
Location: Huddinge, Sweden
Send a message via MSN to runebivrin
I figure it might work if you simply add a copy of the circuit around T5 (220ohm, 3.3uF, 1.8kohm and diode), connect the collectors together and swap emitter and other side of the 220ohm resistor.
That way you've essentially got two detectors back to back.

Rune
__________________
Do wizards use spell checkers?
  Reply With Quote
Old 24th February 2004, 02:11 PM   #6
diyAudio Member
 
metal's Avatar
 
Join Date: Jan 2004
Default More Explaination please

Hi runebivrin

Would you please explain more about what you said above,you mean to switch the connections of the 220 Ohm resistor and emittre,if so,hoe is it going to work.


Thank you for your reply
  Reply With Quote
Old 24th February 2004, 03:05 PM   #7
diyAudio Member
 
runebivrin's Avatar
 
Join Date: Jul 2003
Location: Huddinge, Sweden
Send a message via MSN to runebivrin
Something like this

Rune
Attached Images
File Type: gif protection.gif (6.2 KB, 268 views)
__________________
Do wizards use spell checkers?
  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
Amplifier and speaker protection circuits Peter Daniel Pass Labs 140 18th February 2012 11:14 PM
About discrete I/V stage circuits for a TDA1541A dac gaetan8888 Digital Line Level 5 11th December 2010 08:28 PM
Looking for discrete buffer circuits capable of several watts or so... Lingwendil Solid State 4 17th April 2008 04:52 PM
protection diodes in LM317 circuits jarthel Parts 2 14th September 2006 11:28 PM
Research on tubes and circuits simple circuits Cazcotty Tubes / Valves 6 16th June 2006 01:50 PM


New To Site? Need Help?

All times are GMT. The time now is 08:23 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