Well, 1audio showed us the trick to supply Victors osc. via a 26mA current source.
I did it and it worked well.
Then I wanted to use batteries to get rid of AC hum and groundloops and had the idea to use the current source as charger for batteries, see PIC_1, self explaining.
Five 9V blocks in series give 50,57V in theory ( 5 blocks x7 cells x1,45V ) at full load, but to be on the safe side 50V is enough.
You do want to charge 9V blocks with ca. C/10 - C/15, so 280mAh blocks will be fine. I adjusted the voltage at the input of the LM317HVT to 51.5V via diodes Dx,
much simpler as an additional regulator, then at full charge the charge current will settle at ca. 3mA, at this value ( ca. C/100 ) you may charge them forever without decrease in lifetime.
In case you want to scale down to four 9V blocks, you may use a plain LM317.
One hint, I ordered several cheap 9V blocks via "fleabay" from Asia, forget it, these gave capacities at about 30 to 60mAh, when rated as 300mAh blocks, bummer.
Then I ordered brand names, VARTA and GP, they did well. So, as often, go cheap and finally you'll get expensive ...
Regarding PIC_2:
Left top: Transformer & current source
Right: Victors 1k & 10k Osc.
Bottom: just a rotary switch to monitor each 9V block via a snap-in dig. voltmeter
BR
Gary
I did it and it worked well.
Then I wanted to use batteries to get rid of AC hum and groundloops and had the idea to use the current source as charger for batteries, see PIC_1, self explaining.
Five 9V blocks in series give 50,57V in theory ( 5 blocks x7 cells x1,45V ) at full load, but to be on the safe side 50V is enough.
You do want to charge 9V blocks with ca. C/10 - C/15, so 280mAh blocks will be fine. I adjusted the voltage at the input of the LM317HVT to 51.5V via diodes Dx,
much simpler as an additional regulator, then at full charge the charge current will settle at ca. 3mA, at this value ( ca. C/100 ) you may charge them forever without decrease in lifetime.
In case you want to scale down to four 9V blocks, you may use a plain LM317.
One hint, I ordered several cheap 9V blocks via "fleabay" from Asia, forget it, these gave capacities at about 30 to 60mAh, when rated as 300mAh blocks, bummer.
Then I ordered brand names, VARTA and GP, they did well. So, as often, go cheap and finally you'll get expensive ...
Regarding PIC_2:
Left top: Transformer & current source
Right: Victors 1k & 10k Osc.
Bottom: just a rotary switch to monitor each 9V block via a snap-in dig. voltmeter
BR
Gary
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rechargable battery chemistries have different V, "9 V" batteries are built with different numbers of cells
a very popular "9 V" is 6 cell NiMH which may be only 7.2 V Nine-volt battery - Wikipedia, the free encyclopedia
a very popular "9 V" is 6 cell NiMH which may be only 7.2 V Nine-volt battery - Wikipedia, the free encyclopedia
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