Michael Kiwanuka's SOA PAper

Has anyone considered SOA protection in which the protection transistors are removed from the forward path of the amplifier and, instead, opto-coupled to a bistable which drops out the output relay?

The protection locus would have to be conservative as it would have to accomodate the fact that it may take up to ten milliseconds to drop out the relay.
 

Greg Erskine

Member
Paid Member
2002-01-05 11:56 pm
Sydney
I am not sure why there is a "sudden" interest in SOA protection in numerous threads at the moment. Haven't we DIYers (not professional Electrical Engineers) known about this forever and deliberately decided to accept the risks? I can understand it being extremely important to Electrical Engineers designing consumer products.

Just a couple of points about "reference 3" in the paper. Elliott is spelt with 2 t's and Phil Allison is well known in Australia as a Toaster Repairman with a potty mouth, Phil Allison - Australia | LinkedIn.
 
Use solid state relay. Fast (50-200 us), great repetitive current handling capability (100A no problem), and can handle inductive energy up to 500mJ.

Here is one example: Solid State Relay with PCB Layout

There are quite a few others on DIY audio as well.


Can those relays be used to turn off the supply rails instead of having them in series with the output?

In other words, if SOA protection is invoked or DC offset detected, then disconnect the DC supplies from the amplifier. :scratch2:

A latch would be necessary as you don't want the supply rails re-connected to the amplifier unless power is cycled.
 
I am not sure why there is a "sudden" interest in SOA protection in numerous threads at the moment. Haven't we DIYers (not professional Electrical Engineers) known about this forever and deliberately decided to accept the risks?

Actually I suspect those folk who "accept the risks" do so because they don't know better. The purpose of the paper is to enlighten them.
 

dadod

Member
2006-04-18 3:11 pm
Zagreb
Can those relays be used to turn off the supply rails instead of having them in series with the output?

In other words, if SOA protection is invoked or DC offset detected, then disconnect the DC supplies from the amplifier. :scratch2:

A latch would be necessary as you don't want the supply rails re-connected to the amplifier unless power is cycled.

I use this(similar, a bit upgraded) power supplay with all needed protection. http://www.diyaudio.com/forums/powe...iplier-electronic-protection.html#post2901733
 

dadod

Member
2006-04-18 3:11 pm
Zagreb