Medresco Hearing aid model OL10 boxed believed unused
What a blast to the past. In the 1940s these were high grade hearing aids so this one on offer today would be a wow for anyone into 1940s re-enactment who was deaf!!!!!! Alternatively, during the 1950s, Proops sold these with instructions to convert them into a pocket receiver. And that is precisely what we have here, a brand new hearing aid, in it's box unfortunately without a Proop's instruction sheetf with details of the conversion. Quirky and interesting, can you hear me mother??????
Medresco Hearing aid OL10 with Brush Rothermell earpiece. As issued by UK National Health Service (NHS) from 1955. These hearing aids were named after the Medical Research Council, which held an inquiry into hearing aid design and cost as the government made plans for the new health service in 1948. Development of early hearing aids for the NHS was provided by engineers at the GPO (the forerunner of British Telecom)
This is a three valve unit which needs a 1.25 volt filament supply and 15 volt HT, these would have been supplied by a 1.5volt cell and a 15 Volt battery contained in a similarly shaped battery box and carried around in a leather pouch. The HT consumption is about 250 microamps and the total filament consumption is 20 milliamps. The output valve is a DL64 (CV2331) pentode with 1.25 V 10 mA filament and the two preceding ones are DF64 pentodes with 0.625 V 10 mA filaments wired in series. The valves are wire ended, the anode being that nearest the red spot the other electrodes in order are g2, f+, g1 and f-g3