MM phono preamp with accu and solarcells

[Koifarm]

 

[lcsaszar]

Nice design. What is the purpose of D1/D2?

 

[DF96]

The diodes will do two things: crude match of charging voltage to cell voltage (perhaps not the best way to charge NiMH, but it will work), and preventing reverse current through regulator chip.

C6,7,8 appear in the circuit but not in the parts list.

 

[Pano]

Cool idea. How long does it run on a charge, and how low does it take to charge?
I've run a little Class-D amp off solar, but this is a better idea.

 

[Koifarm]

C5,C6,C7,C8,C9 are all the same 10nf styroflex.

It runs for 20 houres, but when it is daylight it runs just on solarcells. Charging the empty accu's takes about 3 houres. But you can leave the solarscells on, there will no overcharge. At night when you have lights on it is better to switch off the solarcells, otherwise you can get some humm from your AC lights.

Ronny.

 

[arturo1]

Hi, lovely idea and pcb layout. I used to use a single chip amp phono stage powered by a single 9v PP7 battery for long life. Wiring up a simple zener diode controlled power supply from a wall wart mains transformer was an astonishing upgrade. Moral here is that the power supply should have a low impedance, which a battery does not unless you regulate its output.

 

[Koifarm]

Found the schematic and pictures