Simple speaker delay circuit

I recommend you to make a Simple speaker delay circuit.

Imagine you finished a normally OCL power amplifier. Every time you turn on within the first 3 seconds. You may hear sound “tlub…” on a loudspeaker.

You feel annoyed that sound, right? Important, this sound is a high spike voltage. It can damage the loudspeaker.

How it helps us?

This circuit is a delay time to turn on-off your speaker.

The easiest basis of principle. While we turn on a power amplifier. The speaker delay circuit will disconnect the speaker.

It waits for the spike voltage lost before. Then it connects a speaker in normal again.

Ago you would see me try to show you a simple circuit. This too.

See in the circuit below.

How it works

We use 12V power supply from the power amplifier system like this.

A relay in this circuit will cut off a speaker before. Then, Time passed for about 3 seconds, the relay will pull in the speaker to the output of the power amplifier. You will listen to music normally.

speaker delay circuit


Here is the step-by-step process.

The voltage across it is low. No bias current to Base of Q1 through R2. So, Q1 and RY1 do not work.

C1 slowly charge current until full. Then, Q1 gets bias current, it works. To drive a relay pull two contacts together. Connect the speaker to the power amplifier.

The delay time—we can set by C2. If need a long time adds more capacitance. But if shorter reduce the capacitance of C2.

Try it.

What is more?

I am so happy to see you develop yourself. See!


Monitor turn-on delay circuit—Keep safe when power outage. The similar principle uses transistor too. But it uses a direct AC mains with a transformer so small and cheap.

30 minutes timer—Learn basic timer using transistor easy but long time delay.

Time Delay Circuit using MOSFET–Try using MOSFET easy and long-time than transistors.

5-minute time delay—Using NAND gate IC digital. I love it.

Power supply protection

Parts you will need

Q1: CS9013 NPN transistor
C1: 100uF 25V Electrolytic
C2: 100uF 16V Electrolytic
R1, R2: 33K 0.25W 5% Resistor
D1, D2: 1N4007 or 1N4001 Diodes
RY1: Relay 12V coil, 2 Contact 5A or 10A

Which is this circuit suitable for the amplifier types?

  • Low watts normal OCL amplifier lower than 30 watts. Although low power but can kill a small speaker.
  • Without speaker protection.—the common this one has built-in this speaker delay function.
  • Not for OTL amplifier

Look: the loudspeaker protection circuit project


I always try to make Electronics Learning Easy.

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