Author Options:

Pulsated DC Chopper with Inductive load Answered

Components USED

1. MOSFET ( 47N60C3 )

2. Primary Transformer Coil

3. 12V. 2A Switching Power Supply

4.function generator ( currently using 66kHz frequency)


6. Schottky Diode ( PMEG100V060ELPD )

The required output is mentioned with the circuit diagram. I changed the magnitude of function generator gate signal but that was the best I could achieve


1.how to remove the oscillatory part of output?

2. how to get full 12v across the Inductor coil?

3.any other possible ways to achieve the above mentioned required waveform across the inductor coil?

Extra components Available,

extra 2 of 12v,2A power supply


Jack A Lopez

19 days ago

I am guessing that ringing noise, i.e. the fast oscillation with decaying amplitude, is happening right at the instant when the MOSFET switches off.

Actually, I took your oscilloscope picture, and I drew some scribbles on top of it, with me trying to guess at those moments in time when the MOSFET is switching on and off.

The moment when MOSFET switches off is pretty easy to see; i.e. the start of that ringing noise.

The moment when MOSFET switches on is harder to see. It looks like is not turning on very fast.

I mean, if the whole period is about 16 us (microseconds), with %50 duty cycle, that is, 8 us on, and 8 us off, it seems like it is taking about 3 us out of 8 us, for that voltage to rise. Like, uhhh... Like it is having some trouble getting out of bed in the morning. Really, I can relate. ;-)

Regarding the ringing noise, I have seen that before, but I have never been that skilled at getting rid of it. Adding some resistance, in parallel with the inductor and the diode, or maybe in series with it, might help dissipate that stored energy, and damp those oscillations.

Regarding the question of how to get the MOSFET to turn on faster, Downunder35m might be giving us some good advice, with his suggestion to use some kind of driver for the gate on the MOSFET. I have no idea, what he considers "standard parts," since he rarely links to examples.

However, coincidentally, I was looking at this page, at uzzors2k.4hv.org,


in particular, at this circuit diagram,


for a solid state Tesla-coil driver, and I could not help noticing these funny little ICs, namely UCC37321 and UCC37322.

If I look those up, via the usual sources, e.g. a place like alldatasheet.com,


then I discover this IC is some kind of "High Speed Low-Side MOSFET Driver"

Can this IC, or two complementary ICs, UCC37321 and UCC37322 working together, give the gates on your MOSFETS the mojo they need to switch on and off quickly and cleanly?

I don't know if that MOSFET driving juju, using specific those ICs, really works or not. I have not tried it myself. However, I thought the link to this page with uzzors2k's circuit for solid state Tesla-coil (SSTC) might be worth sharing.


20 days ago

So long story short last year I switched into EE, and honestly really dig it so far! Due to my actual electrical course work requiring a different set of math classes than I originally had taken I haven’t been able to take any electrical engineering classes yet... I ended up purchasing some breadboards and parts to go with it, along with a raspberry pi to learn about building circuits and work on some coding as well. The goal is to mess around and learn what I can before I can take an actual circuits course, but from your experience what’re some of the best things I can do to build my knowledge in the field, or any advice on what I SHOULD be doing as well? fedloanirs.gov


22 days ago

I see none of the standard parts such a power supply should have, like gate grivers for starters.
For proper switching mosfets need a strong gate signal.
I highly doubt your function generator is capable of providing the required signal.
And if the power supply you use is not up for the required amps then the voltage will break in and cause, for example oscillations....