Spectrum PSU to ZX81 Switch Cable for Phil

This switch cable allows a Sinclair ZX81 to be powered from ZX Spectrum (UK 1400) PSU. It has a standard 2.1mm DC jack socket at one end, 3.5mm jack plug at the other and an on/off in between. Polarity is matched for respective computers (Outer barrel positive at Spectrum PSU end, tip of plug positive at the ZX81 end)

Please note: A minority of early Spectrum PSUs had DC jack plugs with a 5.0mm diameter barrel - these are too small for this cable (which takes standard 5.5mm diameter plugs) See photo for info on how to check compatibility.