The transformer can pass maximum 750ma from each primary, primary currents do not add up but get subtracted from each other. There are one thousand and one way to get the phase split with total gain of 4 . The input transformer 24$ a pair is the simplest and easiest way, or else I would suggest a double triode gain 12db + phase split and feedback 6db.
Yes you are right, but 750mA seemed a little high - 18W total at 12V. But the optimum would be perhaps a little less, depending on the primary resistance, etc.
Yes you can use a driver transformer but stabilisation and good frequency response may be problematic.
I have found high frequency driver transistor necessary when using a driver transformer and no more than 2 transistors for stability.
A triode circuit would need a high voltage inverter to run, which is why I did not consider it as that would add a bit of an overhead. Not sure if a triode would be able to provide the gate current needed for a MOSFET pair due to gate capacitance, perhaps not enough either for a BJT OPS.
Yes you can use a driver transformer but stabilisation and good frequency response may be problematic.
I have found high frequency driver transistor necessary when using a driver transformer and no more than 2 transistors for stability.
A triode circuit would need a high voltage inverter to run, which is why I did not consider it as that would add a bit of an overhead. Not sure if a triode would be able to provide the gate current needed for a MOSFET pair due to gate capacitance, perhaps not enough either for a BJT OPS.
Gathering and testing
Well, it has been a good 20 years since working with these germaniums, thought it would be a good idea to calibrate the Sencore Beta tester.
Calibration complete, and started going through literally thousands of nos and old stock separated into groups.
I found 2 pair of NOS still in package ECG131MP's so these will be used. The Beta and Icbo leakage were absolutely identical with each pair and quite close channel to channel.
Also tested many 2n2189's for 1st audio, driver and phase inverters matched very tight.
This is not going to be a fire breather, but being built for sonics at low wattage. The journey is the most fun here!
Pics coming as soon as assembly begins... I want to make 2 cute mono-blocks, so they can be dual purpose for some upcoming shortwave regen's and superhet projects or as low power stereo. Have a great weekend!😀
Well, it has been a good 20 years since working with these germaniums, thought it would be a good idea to calibrate the Sencore Beta tester.
Calibration complete, and started going through literally thousands of nos and old stock separated into groups.
I found 2 pair of NOS still in package ECG131MP's so these will be used. The Beta and Icbo leakage were absolutely identical with each pair and quite close channel to channel.
Also tested many 2n2189's for 1st audio, driver and phase inverters matched very tight.
This is not going to be a fire breather, but being built for sonics at low wattage. The journey is the most fun here!
Pics coming as soon as assembly begins... I want to make 2 cute mono-blocks, so they can be dual purpose for some upcoming shortwave regen's and superhet projects or as low power stereo. Have a great weekend!😀