mikeks said:
I knew this long before you even answered. But this is no big problem for me since i run on +-33V rails on my amp. This will not cause destruction on speaker if connected for a very short time.
Now, I would like to see a design from you that works better. Like the use of triacs that i were thinking about.
I have watched with interest but can not help but pass this comment re your protection scheme!
During my last 40 years experience with high power transistor amplifiers I am yet to see a protection system that is of any use! whatsoever that protects the loudspeakers that does not use either a fuse (poor option) or a contactor /relay.
All other sytems will work untill there is a device failure then the result a high dc offset and damaged speakers nearly every time!
Also as stated earlier there are enough parts in your scheme to make another power amp.
So well done in designing and proving your design but would I use it (NO Chance)!!!
For me the scheme that is ideal would be as follows
On switch on the spk are disconnected untill the amplifier is stable ( no switch on thump) Its amazing how many times I have been told the amp was ok when I used it last time!!!.
After a preset time (seconds) the spkeakers are connected provided that there is no DC offset.
Running protection is provided with V-I limiting on the output stag.e
On switch - off the contactor i/relay is disconnected first!
A nice point is panel indication of this operation.
Please note the contactor relay has to be active to connect the spk/load
All other systems that I have seen have always at some time or other damaged the spk/load
I have seen and tried all other systems but as yet can not see any improvement on the good old contactor
Regards Trev
During my last 40 years experience with high power transistor amplifiers I am yet to see a protection system that is of any use! whatsoever that protects the loudspeakers that does not use either a fuse (poor option) or a contactor /relay.
All other sytems will work untill there is a device failure then the result a high dc offset and damaged speakers nearly every time!
Also as stated earlier there are enough parts in your scheme to make another power amp.
So well done in designing and proving your design but would I use it (NO Chance)!!!
For me the scheme that is ideal would be as follows
On switch on the spk are disconnected untill the amplifier is stable ( no switch on thump) Its amazing how many times I have been told the amp was ok when I used it last time!!!.
After a preset time (seconds) the spkeakers are connected provided that there is no DC offset.
Running protection is provided with V-I limiting on the output stag.e
On switch - off the contactor i/relay is disconnected first!
A nice point is panel indication of this operation.
Please note the contactor relay has to be active to connect the spk/load
All other systems that I have seen have always at some time or other damaged the spk/load
I have seen and tried all other systems but as yet can not see any improvement on the good old contactor
Regards Trev
No thats not my point
What I am trying to say is that over the last 40 years I have had many 100,s of customers say to me that the amplifier was working last time I used it ,but when I switched it on the unit started "Smoking Buzzing Whatever "
What I am saying is that an ideal unit would do a self check each time in is switched on and in event of a fault would not connect the load
Now do I believe my customer ?
I think in this case it can cause no harm to do so !
Regards Trev
What I am trying to say is that over the last 40 years I have had many 100,s of customers say to me that the amplifier was working last time I used it ,but when I switched it on the unit started "Smoking Buzzing Whatever "
What I am saying is that an ideal unit would do a self check each time in is switched on and in event of a fault would not connect the load
Now do I believe my customer ?
I think in this case it can cause no harm to do so !
Regards Trev
We live in an imperfect world! there is no perfect solution !so we strive for the best compromise that we can !
As with all things we all have an opinion and we are all entitled to our opinion .
This is our right !
Contactors and relays give assured disconection and if the spk is not connected it can not be blown up !!!
Fact
As you will have noted I always use the term contactor I do not mean some mA operated weak relay that welds at the sign of an amp or so
I have yet to come across an infallable device
And it is a fact that as far as British legislation is concerned no solid state device can be considered for electrical isolation !!!
Regards Trevor
As with all things we all have an opinion and we are all entitled to our opinion .
This is our right !
Contactors and relays give assured disconection and if the spk is not connected it can not be blown up !!!
Fact
As you will have noted I always use the term contactor I do not mean some mA operated weak relay that welds at the sign of an amp or so
I have yet to come across an infallable device
And it is a fact that as far as British legislation is concerned no solid state device can be considered for electrical isolation !!!
Regards Trevor
Please excuse my ignorance here. I've tried downloading the file
http://files.upl.silentwhisper.net/upload5/DCprotectLayout.pdf
in both IE and firefox and I get timeout errors from both.
Is it me? I tried every link in this lengthy post, all to no avail.
http://files.upl.silentwhisper.net/upload5/DCprotectLayout.pdf
in both IE and firefox and I get timeout errors from both.
Is it me? I tried every link in this lengthy post, all to no avail.
DO you tink in theory it might be worthwile looking at using a cheap LM311 voltage comparator IC, set up with a zener as reference voltage, which would trigger a relay when DC voltages hit a specified point.
I use the reverse of this circuit with a zener for model aircraft low voltage alarms...
I use the reverse of this circuit with a zener for model aircraft low voltage alarms...
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