Sparky Circuit Help wanted

[Richard ParsonsParticipant @richardparsons61721]

I know this is strictly not Model Engineering but i am trying to build this tool.

I need some help. Whilst gathering bits and pieces for another project “Mike’s Spark-eroder”. I took my list of bits to an electronic shop. The man gave me all the bits I wanted but 3 of the transistors have different codes on them

Mike list them as :-

TR1 & Tr2 2N3702 (NPN) The Man gave me 2 off BC212 (which is PNP)

TR3 2N3704 (NPN) The man gave me BC337 (which is also NPN)

TR4 TIP32 (PNP) The man gave me BD242 (it appears to be a PNP)

The circuit is like this

How I substitute the new components?

Dick

[Richard ParsonsParticipant @richardparsons61721]

[Les Jones 1Participant @lesjones1]

Hi Dick,

The 2N3702 is PNP so the BC212 should be OK to use. The other two also look to be suitable equivalents.

Les.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Richard, I agree with Les, they should all be OK, but the lead outs for BC212 and BC337 are different from the 2N3702/4, below is a diagram of them.

 

L20 is the BC212/337 and L21 is the 2N3702/4

 

The BD242 and TIP32 have the same lead outs, as in this diagram below.

 

Hope these help.

 

Regards Nick.

[Richard ParsonsParticipant @richardparsons61721]

Les and Nick many thanks to both of you. As I understand you I connect the Emitter of the substitute part as shown in the circuit diagram. Am I right?

Many thanks again

Dick

[Les Jones 1Participant @lesjones1]

Hi Dick,

The difference in the pinout will mean that you will have to bend the leads so that they go into the correct holes in the PCB. (assuming it is built on a PCB.) All three leads still go to the same place on the circuit diagram as this does not relate to the physical construction of the transistors. The emitter is the lead with the arrow on it. The collector is the one that is the mirror image of the emitter but without the arrow and the base is the straight line. I hope this is clear as it is not easy to describe.

 

Les.

[Richard ParsonsParticipant @richardparsons61721]

Les

Once again thanks As Salome said after the 7th veil “All is now revealed”

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Richard, just to show Les’s description, the scan below should make it clearer.

 

Regards Nick.

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