Transistor Hell

Garth

This is driving me crazy. I am missing something. I'm using a BS1 to control a transistor (TIP32A) to switch +24vdc voltage. When I power up and run the sample program I get a constant 24v output from the transistor. I used the LED to indicate when the circuit to the transistor is active. If I pull the conection from the base, then there is no voltage from the transistor.

Is it possible to mix voltages in this manner? I've been reading everything I can get my hands on, fallowing the examples and am able to recreate them however, when I change the example to use mixed voltage I don't get the same results.

Thanks

PJAllen

In your circuit, the PNP will be "on" because whether the Base is 0V/Gnd or 5V it will always be much less positive (more negative) than the Emitter.

If you use a TIP31 instead (NPN), Ground its Emitter and place the load between +24 and the Collector, you'll be alright better off.

I've·amended this to·"better off" because the load is unspecified and the TIP31 isn't a high-beta transistor.· Depending, you may want to go with a Darlington amplifier.




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Post Edited (PJ Allen) : 5/8/2008 1:41:28 PM GMT

metron9

Or use a mosfet like the digikey part no. IRLL024Z-ND it's an N channel 55V 5 amp ultra low on resistance. It is a sot223 surface mount part but big enough to solder to .100 spaced boards.

A through hole mosfet that can handel 60 amps and 24V digikey part # 497-3519-5-ND On resistance in the .01 ohm range.

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
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