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Old 28th September 2011, 01:32 AM   #1
andrewlebon is offline andrewlebon  India
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Default diy short circuit protection

hi
greetings looking for simple diy short circuit protection schematic which can be incoporated into amplifiers any help will be helpful
short circuit i mean if speaker wires touch each other ACCIDENTALLY
warm regards
andrew lebon
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Old 28th September 2011, 01:38 AM   #2
nigelwright7557 is offline nigelwright7557  United Kingdom
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You really need a circuit integrated into the amplifier itself.
Do a search of DIYAUDIO and you find loads.

Alternatively use a fast blow fuse.
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Old 28th September 2011, 01:53 AM   #3
stratus46 is offline stratus46  United States
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Quote:
Originally Posted by nigelwright7557 View Post
<snip>

Alternatively use a fast blow fuse.
Fuses suck. They blow right after the amplifier fails. How about don't fool with the wires while it's running? After I blew up enough amps I decided not to mess with the wiring while it's playing and haven't had an issue in over 30 years.

G
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Old 28th September 2011, 02:03 AM   #4
nigelwright7557 is offline nigelwright7557  United Kingdom
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Quote:
Originally Posted by stratus46 View Post
Fuses suck. They blow right after the amplifier fails. How about don't fool with the wires while it's running? After I blew up enough amps I decided not to mess with the wiring while it's playing and haven't had an issue in over 30 years.

G
I have had some success with fuses.
I tripped over a speaker wire and shorted it out and the fuse blew before the amp. I guess its getting the fuse value right, not so small it blows for no reason and not so big it doesnt blow at all.
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Old 28th September 2011, 02:19 AM   #5
Tajzmaj is offline Tajzmaj  Slovenia
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Transistor is the fastest fuse...
Amplifier must have all protections included in it's own circuit. It is almost impostble to do it ,,outboard,,
But of course fuse can work ..... at least sometimes and it depends what is the amp....build for. If you need it to power some pub....sound system than is more than ok. In case of hi-end, no thanks....it is not just a wite in glass tube but is unlinear element in pwr rails.....or in the signal chain.....it depends. But one thing is sure. In terms of safety very recomended to prevent fire.....or at leat high damage...
Regards, Taj
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Old 28th September 2011, 08:06 AM   #6
gmphadte is offline gmphadte  India
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U have to watch the voltage across the high wattage resistors connected in series with output transistors.

Gajanan Phadte
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Old 5th January 2014, 12:31 PM   #7
andrewlebon is offline andrewlebon  India
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Default protection schematic

Hello
greetings any comments on this protection circuit are welcome
warm regards
andrew lebon
Attached Files
File Type: pdf prot_final.pdf (42.8 KB, 1430 views)
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Old 5th January 2014, 07:17 PM   #8
CBS240 is offline CBS240  United States
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Mr Murphy says that a $10 transistor always blows before a 10 cent fuse.

In This amp I am experimenting with control/protection circuits. Although this one is lower power ~30W(avg)/ch, it uses rail switches for the output stage. The circuit design allows for the entire output stage and drivers to be switched off in the event of a fault. I set this circuit up for a maximum allowable current of 6A. If more tries to flow, then the control circuit not only releases the relay, it switches off the output stage must faster than a blowing fuse. Shorting out the speaker wires simply makes the amp switch back into 'stand-by' mode. I am making a scaled up version of this circuit and intend to apply the same principles. I prefer to control the power rails instead of using something like a crow bar. That concept protects the speaker at the expense of the amplifier.
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Old 6th January 2014, 01:06 AM   #9
andrewlebon is offline andrewlebon  India
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Default short circuit protection

I am making a scaled up version of this circuit and intend to apply the same principles. I prefer to control the power rails instead of using something like a crow bar. That concept protects the speaker at the expense of the amplifier.

Hi CBS240
greetings thanks for replying nice to hear you are also working on protection its good to have protection in amps mistakes do occur while hooking up speakers the ultimate protection by esperado parts are hard to get and ds
pcb OMNI by dr bora works if you short the speaker wires or load impedance is
below 2 ohms but on removing the short it does not reset again it would be nice
if you can share your project if possible
warm regards
andrew lebon
Attached Images
File Type: png PCB protector.png (41.9 KB, 3143 views)
File Type: gif diagrama.gif (14.0 KB, 2857 views)
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Old 6th January 2014, 05:25 PM   #10
still4given is offline still4given  United States
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I'm really glad you guys brought this subject up. I recently bought a speaker protection circuit from ebay and it has a short circuit feature. The DC protection works fine but I don't know how to hook up the short circuit portion. Perhaps one of you can tell me how this is hooked up and if it is worth bothering with. I am attaching the schematic.

Thanks, Terry
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File Type: jpg speaker protection.JPG (60.3 KB, 2829 views)
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