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This transistor is rated as high speed switching and power amplifier. My problem is that it will only support a .7 amp load going thru it from a 12 volt car battery. If I hold the gate high directly from the battery , the amps are the same as when pulsed with a 555 timer. The real amp load is 2.12 A...

I have seen an industrial situation with three phase power that confused the testers of copy machine companies but looked just fine on a multimeter.
I have not read every detail of your situation.
My problem was determined to be a "shared neutral".
Oxford

The problem was solved with a diode on the + hookup to the microphone. The sound quality is terrible but the sound stops when the I.R. light path is interrupted.

Oxford

I can block the light path (I.R.) or simply disable the sending cicuit and the microphone is still audible on the amplification side. Some how the Mic is feeding thru the common power supply. I will try to feed one side thru one diode and the other thru another diode from the +12 post. I guess the -...

Gentlemen, The subject I am on is Pg. 120-121 of Science and communiction circuits and projects (Engineers's MiniNotebook) Forrest Mims III This circuit has two sides . The sending side uses a microphone to modulate an I.R. beam which is focused onto an I.R. phototransitor on the other circuit. Both...

Switch S1A is causing some incredulity on my part if it is able to make lmp1 ,lmp2 or SO2 operate at any time. If you insist , I'll have to make the circuit to believe it.

Oxford