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Topic: dimming Led Strip 70-85V (Read 484 times) previous topic - next topic

janneswa

Hallo, I'd like to dimm a Led Strip in a lamp. The Strips are running with 70-85V.. I measured 75. My arduino pro mini gets 5v from a 230-5v ac dc converter. When i now use analogWrite function to dimm it with a IRF640 N channel mosfet the strips start flickering. With 12V Led Strips its just running fine.

Can anyone give me some advice?

Thanks for any answers.

JayMan

Just off the top of my head you maybe not able to use only 5v or 3.3v to switch voltage that high. I maybe wrong here but I think the higher the voltage you use to control with a transistor the higher the voltage required to saturate the gate.

CrossRoads

"the higher the voltage you use to control with a transistor the higher the voltage required to saturate the gate."

Not true.
BJTs go into saturation with current into the base.

MOSFETs turn in with voltage on the gate.

The trick is finding parts rated to withstand the voltage and the current to be controlled.
These thru-hole 100V rated N-channel MOSFETs would all work, have to select one that can support the needed current, and whose Gate can be driven from 4 to 4.5V, or use another transistor in front of it to swing 10-12V on the gate.
https://www.digikey.com/products/en/discrete-semiconductor-products/transistors-fets-mosfets-single/278?FV=1140050%2C1f140000%2Cmu100V%7C2068%2Cffe00116&mnonly=0&ColumnSort=1000011&page=1&stock=1&pbfree=0&rohs=0&cad=0&datasheet=0&nstock=0&photo=0&nonrohs=0&newproducts=0&k=n-channel+mosfet&quantity=&ptm=0&fid=0&pageSize=25&pkeyword=n-channel+mosfet

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

JayMan

Thanks for the clarification

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