24-10-2016, 01:05 PM
(24-10-2016, 11:25 AM)ppppenguin Wrote: The twin 4.5V batteries (as compared to a single 9V battery) saved the cost of an output coupling capacitor. It was used in a few radios too. You could probably use a single 9V battery if you added a large (100uF+) capacitor in series with the speaker.
I'm not sure why, as a PP9 is very expensive and very much shorter life than two sets of generic Alkaline D cells in suitable replica case.
Especially if i the 4.5V packs run the record player motor?
I have half a dozen PP9 packs that take 6 x Alkaline AA cells, about 1/4 running cost of the hard to find PP9 packs.
If the original was 2 x AD28, those are VERY much lower internal resistance than PP9, Alkaline D cells would be similar.
