A question about alternative power supply for hp41 series

[jebem]

(02-29-2016 01:11 AM)Artur - Brasil Wrote:  I got one small transformer (6+6/500mA), two diodes, one capacitor, one 6Vdc regulator and made the power supply.

Good work, Artur. Thanks for sharing.
Obrigado por compartilhar os resultados de seu trabalho.

From your pictures, I see that you chose to use negative common ground, so the regulator IC would be a 7806 or similar, right?

I can't see from your pictures, but I usually install a small value capacitor at the regulator IC output as well, to improve stability and bypass eventual RF noise.
One Tantalum capacitor with 3.3 to a maximum of 10uF is adequate in this position.
If Tantalum is not available, a regular small value electrolytic cap with a 0.1uF (100nF) ceramic or plastic RF capacitor in parallel will be adequate as well.

Also it seems that you are not using any heat sink with the regulator IC.
Does it get warm?
My guess is that it shouldn't, considering the extremely low current consumption of these 41C/CV machines (The bare machine, that is. If you start adding additional modules, specially a card reader, a substantial amount of current would be expected).

I can't retake current readouts from my 41CV as I'm not at home for a while, but I have some notes in my notebook that I took some time ago when I was restoring it.
For bare 41CV machine, it goes like this:
- Power Off state: 90uA (micro Ampere);
- Power Off to On sequence: 3.9mA;
- Key presses: 3.9mA;
- Power On idle: 0.9mA;
- Executing a program: 3.9mA

EDIT- Before I forget all the details on my readings (human brain memory can be tricky sometimes):
- All the mentioned readings were taken on a 41CV HalfNut;
- I just waited about 30 seconds to take each readings, so I didn't let the machine to settle down;
- The Power Off state current consumption was not steady (it drifted up and down wildly around that 90uA value) - this is most probably caused by one of the internal electrolytic capacitors and should considered as kind of "normal" considering the components aging. Also, 90uA leakage is probably lower than the batteries natural discharge rate.