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This is very basic amplifier circuit,so I use IC digital Cmos 4011 quad NAND gate.
It is to give equal to 10x linear amplifier.
The resistor R1 = 1M ohm , R2 = 10M ohm.
This circuit can not output speaker because it is very low power amplifier.
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LM1875 Channel Stereo Power Amplifier 20 Watt
00W Mosfet [...]

Here is the tone generator circuit,it is small size.
I use IC digital Cmos 4011 quad NAND gate.
This will cause another NAND gate to pulse oscillater which will drive another gate to output a 1.3KHz tone.
The transistor provides drive for the 8 ohm speaker.
The IC 4011 ’s Input pin 1 for Control output tone generator, so [...]

My friend want circuit Bounceless Switch,in testing digtal circuit.
This is Simple Bounceless Switch by 4011 ( hot IC)
The bounceless output have logic digital,it control by S1.
Detail more, Please read in this image circuit.
Thank. Source Simple Bounceless Switch using IC 4011
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