LM2596 problems

#1

Hi all,

I am a newbie in electronics and this year I took some time to focus on it and learn the basics. I am trying to build possibly the most common raspberry pi bot… a battery, a couple of wheels + motors, a buck converter, a motor controller. I want to use a 9V battery with a buck converter (LM2596) and bring it down to 5V (to use it with the raspberry). I bought a few but turning the potentiometers do not seem to vary the output voltage. It is stuck at 8.3/8.5.
Can you give me any pointers about what could i try to make it work? Any help appreciated :slight_smile:
Thanks

#2

Hey - buck converters are fairly complex - did you design a pcb yourself or buy a module or breadboard it or something else?

#3

The easy alternative might be to either use a linear regulator (e.g 7805) - these are less efficient but a lot easier to implement - or some kind of 5v out battery - e.g a usb charger.

#4

No, i bought them online - https://www.amazon.co.uk/LM2596-Converter-3-0-40V-1-5-35V-Supply/dp/B01GJ0SC2C/ref=sr_1_4?keywords=lm2596&qid=1562501205&s=gateway&sr=8-4

#5

Assume you read this: The factory have tested these at max voltage so they are very high by default, takes about 15-20 turns CCW before the voltage starts ramping down)?

If you have - what load are you connecting them to as a test?

#6

Perhaps I have not turn the potentiometers CCW enough. I will give that a go… thanks
I tried both without load and with a 1k ohm resistor. What’s best?

#7

I’ve had a few modules like these that had a faulty potentiometer. Good old chinesium parts. For me it was fine to just replace with a static resistor value.

#8

Be wary that a square 9v battery wont have the power output to run a Pi or motors, this would also cause the regulator to go a bit mad and not regulate.

Courty

3 Likes
#9

I solved the issue… thanks @Calum_Nicoll - i just had to keep turning until 15/20 revolutions. I was scared of breaking them because some sites say not to turn them more than 270 degrees.