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?
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 **broken link removed** or **broken link removed** can be different than a **broken link removed**. ie: The base and collector connections need to be swapped.
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.
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.