One solution is to go USB PD.
For a tape recorder that is nominally 6V...
Get a USB-C power decoy board. Get one that can do 9V.
Feed that into a linear regulator.
Lazy: use a 7805 (emulates half used batteries)
"Parts bin special" - 7806 with a diode or two on the ground terminal to lift the voltage by about 0.7V per diode.
"The right part" a 7806 or equivalent 6V regulator.
Don't forget the bypass capacitors.
That will give you 5 to 6V with almost zero ripple and conducted noise.
The only concern is directly radiated noise from the PD board.
The whole thing then runs off a USB-C mains adaptor.
For a tape recorder that is nominally 6V...
Get a USB-C power decoy board. Get one that can do 9V.
Feed that into a linear regulator.
Lazy: use a 7805 (emulates half used batteries)
"Parts bin special" - 7806 with a diode or two on the ground terminal to lift the voltage by about 0.7V per diode.
"The right part" a 7806 or equivalent 6V regulator.
Don't forget the bypass capacitors.
That will give you 5 to 6V with almost zero ripple and conducted noise.
The only concern is directly radiated noise from the PD board.
The whole thing then runs off a USB-C mains adaptor.
Statistics: Posted by johnkenyon — Thu Nov 27, 2025 9:25 am