/diy/ - Do It Yourself

>>1617623
You already have the circuit. What you need is a real carbon microphone you can hear when you shake it and an audio transformer with a center tap. It will behave like a normal balanced mic. If it is too loud you can encrease the value of the 6K8 resistor to 10K or more. The expensive carbon mic is from https://www.payphone.com/carbon-xmit.html but any other one salvaged from an ancient POTS phone will do as well.