Connecting a transistor and my Uno caught on fire

My goal feels simple: Create a 68 V modulated current using and arduino Uno.

I've connected the base of a NPN MOSFET transistor to my arduino. For some reason after I turn everything on my Uno caught on fire and the base lead starting reading 68 volts.

Will the base lead conduct the voltage away from the transistor at a higher voltage?

Do I just need to put a diode between the base and the Uno?

Did I blow out my transistor and now its conducting through all three lines?

Did I wire my transistor incorrectly?

Help, my wife is going to be mad if I burn the house down.

jpaulmrphy: Did I wire my transistor incorrectly?

I'm going to go with 'yes'. But, it's kinda hard to tell without a schematic.

Sorry, it didn’t load the first time. I’m also showing less than 30 Ohms resistance between all three leads with both the negative and positive leads hooked up in all 6 configurations.

3 x 24V = 72V. MOSFETs don't have bases (or collectors or emitters). BTW what type of MOSFET was it.

But mainly you can't use high side switching like that. The load should be connected to 72V with the MOSFET on the low side of it. Google "Arduino MOSFET switching" and you'll find dozens/hundreds of examples, none looking like yours.

Steve

I'm using an IRF 430 NPN. I'm not quite sure about the "high side" and "low side." I assume you're talking about being before or after the load on the circuit?

What difference does the order of resistor and transistor make?

Looks like some kind of free energy device. Would you please post a link to what to the project you’re trying to duplicate? I find these kinds of projects fascinating ;-)

jpaulmrphy: I'm using an IRF 430 NPN. I'm not quite sure about the "high side" and "low side." I assume you're talking about being before or after the load on the circuit?

What difference does the order of resistor and transistor make?

The difference is that it works if you do it the right way round and it destroys the MOSFET if you do it wrong.

Simplifying horribly, since the gate is connected to an Arduino pin it's voltage can be 0V to 5V. If the source is connected to ground (i.e. on the low side) that makes perfect sense. If the source is way up at 72V then it doesn't.

BTW the IRF340 is not a logic level MOSFET so it will not be fully switched by a 5V signal. That makes it a bad choice anyway.

Steve