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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

high voltage circuit 1 high voltage circuit 2

2SB175 PNP transistor

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    \$\begingroup\$ Have you compared the specifications for a 2N3055 with your 2SB175? They are completely different animals. \$\endgroup\$ – Elliot Alderson Jan 16 at 16:47
  • \$\begingroup\$ lol , yes I compared them but i want a mini thing \$\endgroup\$ – Samsoom Jan 16 at 16:52
  • \$\begingroup\$ What is a "mini thing"? Don't you have a big transformer as well? \$\endgroup\$ – Elliot Alderson Jan 16 at 16:52
  • \$\begingroup\$ I mean a small device easy circuit , 2n3055 need big heatsync , no I want to use aa batteries \$\endgroup\$ – Samsoom Jan 16 at 16:56
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    \$\begingroup\$ You say you have a PNP transistor, but all your schematics show NPN. You should include a schematic of the circuit you are actually proposing to build (use the embedded schematic editor when editing your question). \$\endgroup\$ – The Photon Jan 16 at 17:18
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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

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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.

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