I was trying to power Arduinos from cheap cell phone battery chargers. I found out that if the Arduino didn’t draw enough power from the battery charger, the charger would turn off. In my research I found this load cell circuit that intermittently draws a lot of power in order to trick the battery into staying on. I had to modify the circuit so I could make it with the components I was able to source, then I printed my design and cut and drilled the PCBs. After I made a couple, I was testing them, and they didn’t work. So I took them to a computer science professor at the local university for help. Turns out I had reversed one of the transistors while reworking the PCB design. Next time, I will simply buy different battery chargers, but it was a fun build.