Hi All,
?
I see some very interesting comments about the LM386 PTT Pops solution I suggested in february.
?My latest e-mail generated some confusion as I reported Pin 1 in place of Pin 7 to KC8WBK. Please let me explain why.
My original schematic suggestion taking to RX +12V via pin 7 was thought as simulating the increase in value of 1.35kohm resistor, between pin 8 and pin1 (gain), to reduce gain of the balance amplifier, due to the increase of current through it.
I generated another change schematic where pin 1 was taken to RX +12V, see drawing V2. Next day I was taken to hospital and stayed away from home, between hospital and rehab center for four months. I was convinced to have uploaded such mod and following my memory I commented this mod when I read KC8WBK complain note.
?I was not too shure the simulation of pins 8-1 resistor change would be enough and I addressed my solution to take pin 1 to +12V. This move will block any signal to reach the push-pull stage as + input from pin 3 would never be amplified. The only “puzzle” of this solution would be if the 1.23kohm resistor can dissipate circa 100mW due to a current expected of 8mA, as the PNP darlington transistors, associated to pin 2 - input connected to ground, have a voltage at the emitter of probably +1.4V. If someone will try and demostrate that is not a valid solution and blows the LM386 I will send him a couples as a replacement.... We are experimening .... hi.
?Best 73
?Gian
I7SWX
Giancarlo - I7SWX
