Howto led volt/amp meter show selected current setting before powering load

Thread Starter


Joined Feb 1, 2019
I'm currently building a DIY variable voltage / current power supply. Using a cc / cv buck converter and a LED volt / amp meter...

I would like to have meter to show the amp value before I power the load... So instead of it showing the Value only while the load is being powered...

I am assuming the only viable way of doing so is to hook up a momentary switch that is wired to a power resistor so I can hold the switch and adjust the amp output of the buck regulator so it'll read out on the meter. Correct?

If anyone has any ideas on how I could do this so it always shows the selected amps without constantly powering a power resistor...

And I plan on removing the potentiometers on the buck regulator and installing two bigger ones I'm the outside and the power supply so I can easily adjust them.

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Joined Jun 4, 2014
Once you draw more current than the limit the supply may react in one of three ways:
1. Maintain the current constant and reduce the voltage as the load resistance reduces.
2. It may fold back the current so both the current and voltage reduce as the load resistance reduces.
3. It may trip off completely.

You can do what you want to do if the supply reacts as type 1 - constant current. Then you can simply connect a switch to short circuit the output and the ammeter will display the limited current.
If it is type 2 or 3 then you can't get the ammeter to display the limit.

Thread Starter


Joined Feb 1, 2019
when i connected the power resistor, the buck regulator shuts off until i disconnect the resistor... i used a 5ohm resistor...

no matter what voltage i had i buck regulator set too...

any ideas?

ohh... now that im thinking about it, maybe power supply i used isnt able to provide enough current.. ill keep you posted