If you need a precision voltage source, you have three options. You can spend thousands of dollars and buy a lab instrument from a reputable company, you can spend hundreds and get an amazing enthusiast-grade device from Ian Johnston, or... If you're a cheap ass like me, you can build your own device that might just be enough for your use case at a fraction of the cost, and with hours and hours of fun included for free. Guess what we're going to do!
