help with PWM and volt/amp meter

[KMoffett]

Way lower. Not sure what will work best. That's why I suggested practicing it on scrap PCB.

Ken

[pebe]

I have removed about half a dozen of these pots from converters, so I can give you a run-down on the best method, if you want.

[Macman]

ok great all help is welcome

[Macman]

does it have to be a special pot. I used a 10k pot and the input volts read 11.60 but output now is 2.75 to 1.50 as I turn the pot

[pebe]

How did you get those results if you haven't got the old pot out?

[Macman]

I got the old pot out and wired in the new one

buck (640x480).jpg (148.14 KiB) Viewed 23139 times

[pebe]

The pot needs to be a linear type - nothing special. Your problem is almost certainly be one of these:
1. Have you got the leads to the pot in the correct order? - your centre(white) lead should go to the centre of the three on the pot.
2. Is the current-adjust pot limiting the available current? Try turning the current pot clockwise.
3. Have you damaged the copper connections on the PCB? Check with a magnifier.

[Macman]

seems that its working ok now. I think it was that the motor was bad and was not drawing the volts but I hooked it all up tried a car with a good motor and all is working. just a few cosmetic things to fix tomorrow and I will post a video of the whole thing working. thanks Ken and pebe for you help and patients.

[Macman]

well I said I would post what I made when I finished it so you guys that helped could see what you helped with. I build the box from scratch and its used to carry slot car racing equipment to the track. on top is where all the electrical headaches came from. there are still something's I don't like that im going to work on like how the POT sticks up to high and I think some felt or rubber on the test cell might make it quieter. any way thanks for all the help and advice.

https://youtu.be/1KzSIc1W_lQ

[Macman]

question...why when I put on a car with a motor that has not been tested on the box it starts by going up to almost 12 volts but as I turn down the volts with the pot it will then only go back up to 8 volts then 6 volts. when I remove the car and there is no load on it the meter goes back up to 12 volts. but put the car back on and it still will not reach 12 volts

[KMoffett]

If the current on you meter plateaus as the voltage drops, it sounds like your regulator is going into current limiting. That's adjusted with the other trim pot. Otherwise, if the supply voltage drops below the regulators input limit for 12V than the power supply has insufficient capacity.

Ken