I had the idea to make a power converter, and I would like some feedback. I can take constructive criticism.

The basic idea was to make something where a microcontroller could drive a power MOSFET, with some isolation from the gate capacitance in the form of a pilot BJT. There are also manual start and stop buttons, in addition to the microcontroller input.

The BJT is pre-biased to save board space. I've built and tested this, and it works. However, I feel someone better than me could pick it apart, and guide me in the right direction.

I have the Eagle files in a GitHub repository: https://github.com/gregkrsak/kriner-pc


Thank you.


1 Answer 1


There are hundreds of switch designs on this site. You must define I surge ,, Power dissipation in switch and turn on, off times.

But presently the transistor will needs base current limiting and a base shunt prevent floating when off with stray noise turning it on. Values are not critical. (and I see this part already includes them 4k7,10k)

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Also there is no short circuit protection and the Tact Stop switch does not latch.

There may also be a need to prevent Vgs being exceed by ESD damage from a floating output and connecting long charged floating wires.

  • \$\begingroup\$ The BJT is pre-biased in its TO-92 package. Here's the datasheet: digikey.com/product-detail/en/on-semiconductor/FJN3305RTA/… ...Could you explain what you mean by "short circuit protection"? \$\endgroup\$ Jan 6, 2019 at 20:51
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    \$\begingroup\$ That's better. I'll delete my comment. Short circuit protection for V+,V-. The weakest link will blow 1st ,, supply or the switch. But that's just FYI Some people use Polyfuses for holding current that trips before FET's get too hot for their rated Temp. \$\endgroup\$ Jan 6, 2019 at 20:54

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