I've got a transistorized signal tracer that I am trying to get back into useful condidtion. It runs off of a 9V battery and has 4 transistors. The problem is that even after replacing the electrolytic caps, the volume isn't loud enough to make it useful (I can hear a signal if I hold the speaker to my ear). As the only things left on the circuit board are resistors and transistors, I figure one of more of the transistors is bad. It has three 2SD187 transistors and one 2SB186.<P>Are thre a source for these transistors? If not is a substitute with a modern device possible? This is my first transistor project, so I don't know much about them. Thanks for any help.<P>Jim<P>------------------<BR>

NTE shows a cross reference for these transistors. If you can find a local distributor, they may have them in stock or order them for you. You can find info and specs at NTE's website: <A HREF="http://www.nteinc.com/" TARGET=_blank>http://www.nteinc.com/</A> <BR>Carl<P>------------------<BR>

Hi,<P>If you have a problem finding these, I have the following NTE equiv. ones here.<BR>2N501 for your 2SB186. I have 10 of these.<BR>2N1010 for your 2SD187.I have 1 of these.<P>Let me know if I can be of help to you.<P>Regards, Bob<P>------------------<BR>

Try Radio Shack. It's usually not very critical in these kinds of simple circuits to have an exact match. Just use a similar kind of PNP or NPN transistor. they can help you cross to something or at least tell you if your transistor is PNP, NPN and its basing disgram. <P>Better to find one with matching pinout, there's no set rule for which lead is B, C, or E, but they need to go in the proper position on the circuit. If your substitution isn't the same as the original, just bend them around to reach the correct position.<P>Good to pick up a substitution guide or some other literature to help you learn some of the basics and be able to determine the pinouts of the various devices.<P>-Ed<P>------------------<BR>