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# How to understand electronic part datasheets?? Answered

As a winter chore I'm taking electronic components of circuit boards from salvaged power supplies, printers etc (The toxic work which is usually outsourced to Bangladesh etc....). The purpose is to end up with nicely sorted parts, to be used for future projects. I google the numbers on the 'transistors', but the info on datasheets is almost completely meaningless to me. (I rather would find a short description what one can do with it...)

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## 3 Replies

framistan (author)2009-12-29

The voltages given are maximums the device can withstand.  such as Vce means the maximum voltage from Collector to Emitter.  Transistors have 3 wires.... Emitter, Base, and Collector.  The Diodes have PIV rating... that means Peak Inverse Voltage... or the maximum voltage the diode can withstand in the reverse direction.   "Ic"  is Current in the collector maximum.  Few of us understand all of that stuff in the data sheets either. so dont feel too bad about it.  Here's one example of how to use the information.  Lets say you have a circuit you are building that needs to rectify 18volts peak voltage in a power supply.  The transformer only puts out half an amp.  so you find a diode in your junkpile that the datasheet  rates as 200 PIV and 2 amps. ... that would work OK because your transformer only puts out 500 milliamps (half an amp). and far less than the 200 volts. so you would be OK using that diode.  Other abbreviations you can work out the meaning of by the examples i have given. for example.... if you are working with an FET (field-effect-transistor), the data sheet will not show E, B, and C... because those are transistor pins... The FET uses S,G, and D... for source, drain and gate pins.  (if my memory serves correctly???)   As long as you pick a device that is rated HIGHER than your circuit requires, you will be ok.

BobS (author)2009-12-29

After an afternoons work I have a shoebox full of stuff: small transformers, caps, inductors, power resistors and -diodes (the small stuff I leave on the board for now, the paint strip gun discolors the resistors so it's hard to read the color code).

Some specialized TV stuff, but also a 3A stepper driver, a voltage regulator, some MOSFETS and power transistors. The larger chips I keep for now, right now this is still way over my head.

The boards still contain large amounts of solder, so I keep them, to later recycle it.

I guess I have to take this slowly, I got very overwhelmed at first...

steveastrouk (author)2009-12-29

Transistor datasheets ARE detailed things. For your kind of applications, apart from transistor type (bipolar/npn/pnp  (mos)fet/nchannel/pchannel/enhancement/depletion mode) look at the maximum Vce, or Vds, the Hfe or Beta, and Vce(sat) (Vdsmax) Vgs max is also useful.