Bob Edge
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View attachment lift.pdf
Hi,
I have a circuit (attached) that is used to drive a coil. The coil switches on for upto 2 seconds. The capacitor C24 charges to roughly 150V, when the coil is energised it gets an initial high voltage, then this quickly settles down to 24V, since the current is supplied through the six resistors. My trouble is that the switching device Q2 fails, not very often, but enough for it to be a problem. I have tried MOSFET's and IGBT's (with Q1 removed) but I still get the odd faliure. The coil is 8 ohms, and 26mH @ 1KHz.
Can anyone see what the problem is, or maybe sugest a bullet proof way to do the job?
Regards
Bob.
Hi,
I have a circuit (attached) that is used to drive a coil. The coil switches on for upto 2 seconds. The capacitor C24 charges to roughly 150V, when the coil is energised it gets an initial high voltage, then this quickly settles down to 24V, since the current is supplied through the six resistors. My trouble is that the switching device Q2 fails, not very often, but enough for it to be a problem. I have tried MOSFET's and IGBT's (with Q1 removed) but I still get the odd faliure. The coil is 8 ohms, and 26mH @ 1KHz.
Can anyone see what the problem is, or maybe sugest a bullet proof way to do the job?
Regards
Bob.