Transistors

[daz061]

hope this is understandable, im not too good at putting in words what i mean. if a projects asks for certain transistors but you dont have them you may have another that will do the job tucked away somewhere,  what is the best way to go about finding replacements like what specs do you look at that are important etc

[jrod]

You might try a google search with the part number.

Also you could try searching for the part you have on alltransistor.com and looking at the list of equivalent part numbers.

www.datasheetarchive.com is another site that will show possible substitutions.

[R.G.]

1. Get the correct kind: bipolar (NPN/PNP), JFET, MOSFET
2. Get the correct material ( silicon versus germanium)
3. Get the right polarity: NPN/PNP, N-channel or P-channel
4. Get enough voltage rating. Generally for 9V powered pedals you can't get any that won't work because they're too low. Most small signal devices are good for 20-50V.
5. Get enough current and power rating. Generally for 9V powered pedals you can't get any that won't work because the power/current needs are small.
6. Get enough gain for bipolars. Generally, you want hfe of at least 100, preferably 200-600.

This line of reasoning led to Keen's Second Law: when in doubt, use a 2N5088. There are remarkably few places needing an NPN silicon in a pedal where a 2N5088 won't work OK if not great. The near-ubiquitous 2N3904 comes close too, it's just not as quiet or high gain. The 2N5086/87 and 2N3906 are good generic choices for PNPs.

[daz061]

Thanks, some good advice here.

[duck_arse]

I'm a big fan of the second law, except I take great delight in reaching for a BC548B, every time. well, first off.

welcome to the forum.

[GibsonGM]

What is a BC548B, Duck??  The Oz equivalent of a 2N3904?  Or 2N2222A?   ;o)   We have to order things like that.

Now that most all electronics shops are gone, heck, we have to order EVERYTHING!! 

[slacker]

It's the European equivalent of a 2N5088, well not strictly equivalent but same sort of specs, high gain, low noise, easier to get over here.

[GibsonGM]

It's the European equivalent of a 2N5088, well not strictly equivalent but same sort of specs, high gain, low noise, easier to get over here.

+1  thanks, I was teasing Duck.  ;o)

I don't know why shops like Radio Shack decided to carry what they did/do here, but it seems we have missed out quite a bit in the US - no BC547, for instance.  Have always had to fudge the transistors when schematics calling for such have popped up.   Now that we order everything from Mouser and others, though, we can get them same as anyone.    Not that they weren't there, just weren't popular - ham radio guys always 'ordered out'...

[armdnrdy]

I don't know why shops like Radio Shack decided to carry what they did/do here, but it seems we have missed out quite a bit in the US - no BC547, for instance.  Have always had to fudge the transistors when schematics calling for such have popped up.   Now that we order everything from Mouser and others, though, we can get them same as anyone.    Not that they weren't there, just weren't popular - ham radio guys always 'ordered out'...

What I've gathered is 2N is American, BC is European, and 2SC is Japanese.

The Russians have KT.

It wouldn't make much sense for Radio Shack to carry European general purpose transistors when they already stock American general purpose transistors.

Bend the legs.  

Edit:
Here is some reference material about coding:
http://dmohankumar.wordpress.com/2012/04/24/know-the-meaning-of-transistor-and-ic-codes/

http://www.mikroe.com/old/books/keu/04.htm

[duck_arse]

I don't know why shops like Radio Shack decided to carry what they did/do here, but it seems we have missed out quite a bit in the US - no BC547, for instance.  Have always had to fudge the transistors when schematics calling for such have popped up.   Now that we order everything from Mouser and others, though, we can get them same as anyone.    Not that they weren't there, just weren't popular - ham radio guys always 'ordered out'...

What I've gathered is 2N is American, BC is European, and 2SC is Japanese.

The Russians have KT.

hah-ha! and the australians had the TT800 and the TT801 (and manufacturing industries). that's about it, as far as I know, they was made by ITT Australia.

[edit:] what I meant to say was, just order whatever is the cheapest, these days, w/ the mojo wires and all.