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I want to make one of those circuits using an old PNP germanium transistor (2SB175) what values of resistors should I chose and which circuit is good ? , if the circuits are bad, is there any better arc generator (hv) circuit using this transistor (2SB175) ?
Could anyone please help me. Thanks
the transistor of 2sb175 is poor transistor it is a signal transistor vce=30v, ic=100mA
But the 2n3055 is a power transistor: vce=60v, ic=15A and it support a high current to diver a good current to supply the primary of step up transformer to generate a high voltge at the secondery coil
from this point you can't replace 2n3055 by 2sb175
if you want to make this circuit just buy a 2N3055
if you want to make this circuit with PNP power transistor just invert the power supply
Those old germanium transistors are very intolerant of abuse (ask me how I know). Note the abs maximum junction temperature of only 85°C and maximum power dissipation of 125mW at Ta = 25°C (meaning that it's really only good for a few tens of mW).
They're not really suited for experimentation with unknown flyback transformers, the most likely outcome is that you'll fry the transistor before you learn anything.
It is not impossible to make some kind of very low current high voltage generator with that transistor, but it would involve some effort and knowledge, and you're never going to see big awe-inspiring arcs (or even much in the way of little sparks) coming from that transformer secondary.
