Another Hamfest find is the Sinclair Radionics PDM 35 digital multimeter. Having grown up with ZX Sinclair Spectrum clone, and reading a lot about Sir Clive Sinclair and his creation I wasn’t about to walk by this. If the look of it is a bit calculator-like, that’s because they actually reused a calculator enclosure! This was a cheap model, selling for 33 pounds in the 70-s and 80s
Here is the BMS that came with my Headway LiFePO4 cells. After a few pictures it’ll be very clear why I felt really leery about entrusting my cells to its care.