for a cw-shaping circuit with an op-amp (second order key-klick filter by Jim Moritz) I need an inverter for the negative supply of the op-amp. It is not possible to choose an dc/dc-converter, as most of these devices operate at frequencies of 100 kHz...500 kHz, just where the receiver will run.
So it is necessary to design an inverter with an transformer running at 100 Hz...500 Hz, what is a good frequency for laminated cores designed for 50 Hz ac. Effectivity may be low, as the circuit will draw only a few mA at voltages of -5...-12V, when powered at +12V. My current thought: Astable multivib followed by driver-transistor and an 230V/12V-12V-Transformer (the 230V ac-windign will not be used). After rectification and stabilisation an voltage of -4V...-6V seems to be feasable.
Have You already done somthing similar? Any proposals warmly welcome.
DK 8 ND cba
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