Hi, I'm an electric tinkerer on the really low level. Now I made a project where I needed a step up module from 12v to 24 v , but externally regulable. The little screw which does just that on the step up module is inaccesible when in the project box. So I thought why not add a potmeter behind the step-up? Which I did, a10k linear, now when I switched on the circuit, the step-up fried. In particular, a tiny six-legged chip/transistor went up in smoke. What didi I do wrong? I'm sure all leads wher correct and I hooked the potmeter up with its 3 pins, using middle as + out. It's the addition of the potmeter that killed the step-up (MT3608)

 

Welcome to AAC!
Connecting a pot of arbitrary value in an inappropriate way is asking for trouble. The existing voltage adjuster may have been wired as a rheostat rather than a potentiometer. Do you have a schematic of the module? How did you decide on 10k? Did you remove the existing adjuster?

 

Draw the original circuit out on paper, or find a print out of it online. Then draw or modify the print out to add your POT. If you don't see the problem then post both drawings here and we can help.

 

First, did the module work prior to making this change? Next, with three terminals there are nine possible connection arrangements and at least seven of them a re wrong. And did you remove the internal adjustment device, or just solder wires to it.
And I am guessing that there was a short-circuit created and that caused the problem.

 

Yes, I'm pretty sure I short circuited the step up. As for diagram: it's a MT3608. I set it to produce 24v from a 12v input. Now I had to be able to control that 24v output from 0 to 24v, which I can't do on the MT3608 itself as I can't access it from outside. So I soldered a wire from + out (of the step up) to left pin of simple 10k potmeter then I wired the middle pin of the pot to the outside positive voltage point where I can tap the desired voltage and connected the right potmeter pin to GND and to negative voltage point tap (it's just GND of the entire system.). So that's not the correct way. How can I control the delivered 24v with an outside control knob? Remember: the step up is inaccessible from the outside.