speaker protection circuit help?

Thread Starter


Joined Jul 29, 2007
i hv got this speaker protection circuit without full component details.
Only details with me r
IC = CD 4049
C1 = .22k/250v

R1 = 100K ( I think)
R2 = 2.2 OHM ( I think)
R3 = 1M ( I think)
C4 = .47ufd ( I think)
C3 = 470ufd/16 ( I think)
R4 = 5.1k ( I think)

Modifications :

Further i want to use speaker rectified power for supply of CD 4049 with one
9V regulator. My speaker is big one. Hence output AC is also high. I will supply the powersupply before regulator to relay. I want to use 12V DC relay.

Suggestion & Guidance from fellow members is expected.
Thanks in advance,



Joined Apr 20, 2004
Your CMOS IC will work with up to 18 volts for Vcc, so the rugulator won't be necessary.

If I were going to use a protection circuit, I would want to apply the rectified DC to a comparitor, and let that trigger to open the relay.

Your schematic is cut off so the stuff from the left of the bridge is cut off. That makes it a bit of guesswork to say how the circuit might be modified for a larger amp.

Thread Starter


Joined Jul 29, 2007
Thanks beenthere,
I appreciate ur valuable advice. But can u guide me to some better circuit?

In the said circuit we connect a resistor in the signal path when the relay cutoff the speaker signal.


Joined Jun 30, 2006
Look at some of the stuff for the high wattage car audio industry. I recall a self resetting fuse that worked well but you did have to know some information on the amp and speakers and it would not prevent some forms of damage just over current/wattage limits.

Most good amps will test the outputs constantly looking for faults.

Schematic and explainations

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