Induction coil interupter same as spark gap radio?

[MagnaProp]

Thanks for the help guys. I have tried to correct the attached wiring diagram.

Am I correct that the pins of the Mosfet are ...

Gate = Signal from signal generator.
Drain    = +
Source = -


I'm a little confused by the following partial quotes...
unimmortal  "...10k resistor needs to go from gates to source (pin 1 to pin 3), which is also the negative on the battery..."
magluvin "...drain of the mosfet needs to go direct to the neg of the battery..."

Unimmortal makes it sound like the "source" pin is negative.
magluvin makes it sound like the 'drain" pin is negative.

Perhaps it is high side vs low side switching confusion? I don't yet understand which one we are doing here if that is the case.

Thanks again for putting up with my newb questions. It's greatly appreciated.

[unimmortal]

Ok, connect your coil from the (+) of your battery to pin 2 (drain=power&load) of the FET. Connect pin3 (source) to (-). This is low side switching or N channel - switching everything to negative. High side is switching power to a load through a FET. A little more fiddly as you have to give a P channel FET a relative negative voltage, which you can do with a two resistor voltage divider

The signal generator 'should' connect red lead to the gate of the FET and the black lead to source. You'll have an AC wave from the sig gen, set it to be a very short duty cycle to get that sharp pulse.

[Jim Mac]

I think they are both right, just the wording is confusing.  N channel mosfets switch the negative and do not directly connect with positive to the source.

Battery HOT to the load Input.  Out of the Load to Drain.  Out of the source to Battery Negative.  10K resistor between the outer 2 pins. Then fire the gate.

Think of it like the normal way we install light switches.  We switch the negative wire open and closed. 

That's how I hook em up usually.

[Uniongarage]

Old automotive ignition modules work very well at low voltage switches that can handle 6to8 amps at 12 volts lower frequency.

[MagnaProp]

Old automotive ignition modules work very well at low voltage switches that can handle 6to8 amps at 12 volts lower frequency.

Good to know and thanks for the info. I'll look into that.

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Thanks guys. Giving it a third try here. Let me know if one looks correct or if I should go back to stamp collecting.

The "JimMac" one is my interpretation of his directions.
The "Unimmortal" one is my interpretation of his directions.

[Jim Mac]

Thanks guys. Giving it a third try here. Let me know if one looks correct or if I should go back to stamp collecting.

The "JimMac" one is my interpretation of his directions.
The "Unimmortal" one is my interpretation of his directions.

I wouldn't run it the 2nd way, you have a dead short and will fry the FET

   

[unimmortal]

Power (+) --> Load --> Drain (pin 2)

The ability to put 2-4V (max) on the gate to open it is called enhancement mode for the IFR540N.

Check the datasheet for the specs. Vgs is the gate to source relative voltage. It'll also have your delay, rise, fall times to help calculate complete switching cycle timings.

Let us know how you get on.

[MagnaProp]

I wouldn't run it the 2nd way, you have a dead short and will fry the FET

Thanks for the info. I'll give your method a try.

Power (+) --> Load --> Drain (pin 2)
The ability to put 2-4V (max) on the gate to open it is called enhancement mode for the IFR540N.
Check the datasheet for the specs. Vgs is the gate to source relative voltage. It'll also have your delay, rise, fall times to help calculate complete switching cycle timings.
Let us know how you get on.

Good to know thanks. So just to be clear are you saying the attached wiring diagram I did of your setup was correct for what you discribed? I'm not sure if I interpreted your discription correctly or not. It's always good to learn different ways of doing things so thanks for that.

[unimmortal]

Good to know thanks. So just to be clear are you saying the attached wiring diagram I did of your setup was correct for what you discribed? I'm not sure if I interpreted your discription correctly or not. It's always good to learn different ways of doing things so thanks for that.

Don't run power (+) to anything but the load, the load then connects to the drain. As mentinoed above, you'll fry stuff otherwise Guests cannot see images in the messages. Please register at the forum by clicking here to see images.

[MagnaProp]

Sounds good. I'll order some parts and hope I don't release the magic smoke. Thanks again guys.