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SiriusHardware · 17th May 2021, 11:20 pm

The 'Low' input voltage which feeds the regulator (TR5 and associated) is perhaps higher than I might have guessed it would be, my guess would be around 8V-9V. The reverse / overvoltage protection diode for that supply input (DZ4) is 18V, a bit more headroom than I would have expected but maybe that just shows that the 'low' input supply is unregulated, as an unregulated supply which is nominally 9V on full load could easily knock out 13V-14V when lightly loaded.

17th May 2021, 11:20 pm	#86
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,556	Re: Early EPROM programmer. The 'Low' input voltage which feeds the regulator (TR5 and associated) is perhaps higher than I might have guessed it would be, my guess would be around 8V-9V. The reverse / overvoltage protection diode for that supply input (DZ4) is 18V, a bit more headroom than I would have expected but maybe that just shows that the 'low' input supply is unregulated, as an unregulated supply which is nominally 9V on full load could easily knock out 13V-14V when lightly loaded.