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newbie questions about transistors

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josephbtravis

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I constructed an astable multivibrator from instructions in my 300 in 1 electronics kit, but have accidentally burnt out the 5 transistors that came with it. I went to radio shack today to get some replacements, and found that they didn't work when I threw them in. It wasn't until then that I realized that all transistors aren't created equal. I knew about pnp and npn, but I didn't realize that one npn was different from another npn.
So I'm at a loss as to how to get my multivibrator working again. The ones I was using were labeled "C1740" with "S RG" under that. I haven't been able to find any information about them.
The transistors I picked up at radioshack were 2N3906 PNP and 2N2222 NPN transistors. What is the difference between these and the C1740 that I had before? Why didn't they work? Is the C1740 something obscure that I won't be able to find a replacement for at radioshack?
 

kchriste

New Member
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A 2N3904 or 2n2222, while not an exact match for your 2SC1740, should work for most, if not all, of the experiments in the 300 in 1 kit. It is more likely that you got the EBC pinout wrong because the pinout of a 2N3904 or 2N2222 can be different than a 2SC1740. ie: The base and collector connections need to be swapped.
 
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MrDEB

Well-Known Member
LOOK at the pin out

the pin outs are completely different.
look at the data sheets that kchriste posted.
 

gccradioscience

New Member
I am very familiar with the C and A series transistors. The C type is NPN with a pinout of E C B, The A type is PNP with a pinout of E C B they are used in lab kits worldwide. The ones you were using that are the 2N type have a pinout of E B C. They can be quite confusing, but when you are substituting transistors you will need a multimeter with Hfe readout and pin readout display.
 
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audioguru

Well-Known Member
Most Helpful Member
My question is How did you burn out the orginal transistors?
It is easy to burn out transistors when you don't have their datasheets to see their pin-outs and max allowed ratings.
A 12V/1A power supply connected directly to a forward-biased base-emitter or forward-biased base-collector junction will let the magic smoke out.
Too much power dissipation will also fry a transistor.
 

MrDEB

Well-Known Member
But I think the op stated that this is a 300 in one kit so maybe the op didn't follow the directions with the kit??
 
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