I scoured through the forums but could not find a good answer. I'll first explain what I am trying to accomplish, and then what I currently have. I have a need to vary the voltage that is output from a 3.7v Lithium-Ion battery. Most uses are either 6v,9v or 12v (2.1mm dc plug). I am using an old LM2577 circuit I previously built, the voltage output was adjusted using a 10K Ohm Variable Resistor. I removed the variable resistor and was looking to use a digital potentiometer instead that was controlled using an Arduino. The potentiometer I have is a mcp41010. However, I have two problems: 1) Current in the LM2577 circuit is too high (16mA) 2) Voltage in the LM2577 where the variable resistor was is too high (43V when open). The first problem I can fix using a current limiting resistor, but I am clueless on how to address the second problem. I was looking at conceding on using a digital pot and instead use some simple transistor circuit instead to feed the correct voltage into the wiper input of the where the original variable resistor was. I was even looking at using a LM317t variable resistor, but I have no means of using the adjust pin (I have no OP AMPs available - plus I feel all that circuitry is unnecessary to just replace a simple variable resistor) Does anyone have any suggestions for this? Thanks for any help received!