Uno, Mosfet, Boost converter unstable

Using Arduino General Electronics
1

I'm switching a small boost converter with a Mosfet IRF820B using the UNO. The converter is running series LEDs at about 20V. Source power 12V.
Problem: When I switch it with the Uno the converter output is stable and correct sometimes. On other times it goes up to about 30V which drives the LEDs too hard and the Mosfet heats up massively, drawing far too much current. The converter is in the earth leg.
If I turn the Mosfet on by directly connecting the gate to 5V it never happens.
Any pointers or ideas as to what is going on here and what I might try.
Help much appreciated
Andy

2

Can we see a schematic? And, a link to the boost converter datasheet?

3

In addition to DVDdoug you should try to sketch the connections between the power supply(s), Arduino and boost converter.

Odds are the issue is in the wiring or supply capacity but without more information it is only a guess.

Also, I'm curious, how are you controlling the current to the LED's?

4

Note that an IRF820B is not a logic level fet, and needs more than 5volt at the gate if it has to switch significant current.
Leo..

5

Sorry folks. My fault. JohnRob was right. Messy wiring. The xl6009 module has + and - In and Out. I had connected the Out - to board earth and Not connected In-. Having corrected that it works perfectly. The mosfet works perfectly for the moment.
I'm controlling the current to the Leds by reducing the voltage. I want them dim. When I get the initial hook-up working with the software I'll look at currents and loads and so on.

Thanks