Are all TIP107's the same?

musicman282

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The H-bridge motor drive board in my Red and Ted's roadshow wasn't properly driving Red's mouth. I suspected it was bad transistors in the H-drive circuit. I replaced the TIP102 and TIP107s and the motor would hardly move. It would just click for open and click for close. I tested the motor on the circuit for TED to rule out a bad motor and the motor works strong as can be.

I spent a ton of time double checking the connections and my soldering and scoping the circuit. Luckily the board has two identical H-bridge circuits so I can compare the two with my scope. I narrowed it down to low voltage coming off the emmiter of the new TIP 107!!

Well out of curiousity, I swapped the TIP107's from the TED circuit over to the RED circuit and volia!! RED's mouth works perfect. So my question is, are there differences in tip107's? I poured over the datasheet and couldn't find any differences between all the models offered on digikey.

Does anyone know the exact specs of the TIP107's used in this circuit?

Any help would be greatly appreciated. I'm planning on ordering some more transistors from mouser this time to make sure they're from a different batch in case I just got some bum parts.
 
Another interesting development. I measured the base to emitter drop with my diode checker and I got a reading of. 742v for the working tip107 and. 846v for the non working tip107. I think this could be causing my problem.
 
Another interesting development. I measured the base to emitter drop with my diode checker and I got a reading of. 742v for the working tip107 and. 846v for the non working tip107. I think this could be causing my problem.

Sorry for the snippy sounding reply earlier, I had something urgent pop up and didn't get in the other stuff I wanted to put in there. In your case, I suspect you came across a rare instance of a new transistor being dead.

The different ones you're seeing in digikey are for a few reasons, though most of them are just fine for you to use. The TIP107G by ON Semiconductor is a certified lead-free part, to differentiate it from their older part number that does contain lead. All the rest of them are all lead-free. However there is also a TIP107TU by Fairchild which is intended to operate with negative DC voltage. That's the only one that shouldn't work. All the others should be ok to use.

-Hans
 
ya doa parts can happen, sometimes you can damage them by leaving the iron on the part for too long also... not sure if TIP series xistors are static sensitive but CMOS devices definitely are
 
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