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Old 29th November 2013, 08:31 PM   #1
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Default Lowering the AC Votage to my speaker protetion circuit.

Hi Guys,

I am finishing up an amp build and had planned to install a speaker protection circuit. The circuit I have requires 12V-15Vac supply. The transformer I am using in the amp has a separate 16.5-0-16.5vac that I had planned to use for the speaker protection circuit. Is there a way to lower that to 15vac? I tried it as is and it over-heats the bridge in the SP circuit so to use it I will need to reduce the ac.

Thanks, Terry
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Old 29th November 2013, 09:12 PM   #2
Andonio is offline Andonio  Italy
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Quote:
Originally Posted by still4given View Post
Hi Guys,

I am finishing up an amp build and had planned to install a speaker protection circuit. The circuit I have requires 12V-15Vac supply. The transformer I am using in the amp has a separate 16.5-0-16.5vac that I had planned to use for the speaker protection circuit. Is there a way to lower that to 15vac? I tried it as is and it over-heats the bridge in the SP circuit so to use it I will need to reduce the ac.

Thanks, Terry
you can use a rectifier bridge with 3 or 4 diodes for each side. (You should made it with discrete diodes). In such a way you can loose 1.8 to 2,4 volt for each side of the rectifier bridge.
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Old 29th November 2013, 10:16 PM   #3
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I don't think that will work. It needs 12 -15 vac. What you show gives DC.
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Old 29th November 2013, 10:28 PM   #4
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Hi,
Just remove the capacitor and you get dc pulsating. Almost AC without the negative pulse.
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Old 29th November 2013, 10:34 PM   #5
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Not sure the SP will accept that.
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Old 29th November 2013, 10:37 PM   #6
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Hi,
Can you post your SP schematic?
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Old 29th November 2013, 10:37 PM   #7
Andonio is offline Andonio  Italy
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You can feed your speaker protection circuit with DC (instead of AC) since you have in the protection circuit another bridge that can work also with DC input
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Old 29th November 2013, 10:47 PM   #8
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I will try feeding it with a 12v dc circuit and see if it accepts it.
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Old 30th November 2013, 08:33 AM   #9
Andonio is offline Andonio  Italy
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After a night's sleep, this morning I thought this possibility:
in this way you can power, with reduced AC, the speaker protection circuit
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Old 30th November 2013, 12:51 PM   #10
Vostro is offline Vostro  Madagascar
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maybe its easier to modify circuit, i.e place resistor in series with relay etc
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