Is it possible to change the 12V output of a U3V70F12 12V voltage regulator board to 6V instead? The board looks identical to U3V70F6, so I’m assuming the output is set based on some fixed resistance value. I’d like to replace the resistors to change the output instead of buying a whole new board. Which resistors would I have to change and to what value?
Also, would this then allow the performance of the board to be identical to the 6V version? The adjustable voltage version only lists a graph in terms of percentage. It does not have any resistance listed, so it’s not very helpful to determine from there.
It is possible to change the output voltage of the U3V70F12 regulator by changing two resistors labeled in this picture.
To get 6V out of that regulator, the ratio between resistor 5 and 6 should be about 4:1. Since resistor 5 is 300kΩ on the 12V version of the regulator, you could try replacing resistor 6 with a 75kΩ resistor to get 6V from the output. I expect changing R6 to a 75kΩ resistor will result in your regulator having near identical specs to the U3V70F6 regulator.
Thank you for your reply. I will try to replace it and see what I get.
On the subject of voltage change, does the 4:1 ratio only apply to 6V? I’d also like to get 9V out of another one that I have. What should the R5 and R6 values be in this case?
Yes, the 4:1 is only for 6V. If you would like to set the output voltage to 9V, the ratio of the resistors should be 6.5:1.
Thanks. Does it matter if the values are low? As in, can I use 1k or 10k instead of 100k resistors?
Using lower value resistors will result in more wasted power. I recommend using a resistor value between 10kΩ ~ 100kΩ for R6.