A simple but effective design, can't find a circuit or even another radio, perhaps I've got the model number wrong? I think Pye owned the company from 1949. It uses the Mullard 'OC' silicon type transistors used around 1959-62 period, they were glass envelopes painted over in black, if the paint was removed they became light sensitive and could be used as movement detectors. I stripped it all down for a good clean then added 2 x LED's to front dial window.
The cabinet is red Rexine covered heat moulded plywood, not so popular in the day and loosing sales to the smaller light 'tiny' sounding plastic transistors. As not many are around I thought it was worth saving.
At least Invicta had taken on printed circuitry idea that was the big improvement of the day, no solder tags or terminal strips needed, ferrite rod aerial coils were now the main signal collector component, these had start to arrive in radios around 1950.
The one thing that can stop a raid dead in it's tracks is a dirty contacts band switch, some switch cleaner and an old tooth brush in all switch positions gets at most of the silvered contacts. Bulbs were rarely fitted in portable radios as the current 150-300mA would run a battery down fast. But today LED's only draw around 2-5mA and can be left on all the time.
Battery clips had been crudely repaired, I installed a battery box with 6 x 1.5 v cells allowing me to take off 3V to the LED's. I replaced the 15uF that fed the volume control to the audio driver, that was o/c causing low sound. The only drawback with 1.5V battery's they will leak acid after a while, so best not to leave them in when not in use. The top photo is the eBay one, so you can see it was in good nick when I found (saved) it. If anyone knows the right model number or had circuit please let me know - love Nold
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