On eBay I bought a few of the LM2596 buck converters with constant current to use with the 10 watt LEDs I bought, and received them in the mail today. Now I don’t need a 1 or 2 ohm resistor at several watts to limit the current and waste power. Problem is it’s difficult to find info on the pots and indicator LEDs on the board.
The PC board has three adjustable trimmer pots and three indicator LEDs. The auction gives information about adjusting for the voltage then shorting it with an ammeter and adjusting for the current. Problem is there is nothing – no labels, no part numbers – to indicate which trimpot or LED does what. For instance, it says “The charge current of transfer lamp is default 0.1 times of the charging current (constant current value)” I’m still trying to figure out what that means.
I looked up the name on the back of the PC board and came up with nothing useful. In any case, I’ll have to do some experimenting with it and find out what’s what.
Update Jan 8 – I found that the trimmer on the right (see pic) is the voltage adjust. The trimmer on the left seems to adjust current, but when I short circuited the output (according to the instructions) the current was sometimes limited, and sometimes it went up to the half amp maximum limit of the small power supply I was using for the test. This odd behavior could have been caused by the power supply. I’ll have to test it with a wall wart that can put out more than an amp.