Woodstock Low Power

[PANAMATIK]

(07-26-2017 04:57 PM)Maximilian Hohmann Wrote:  Wonderful!

What do you suggest for the power supply? Will two AA cells (ideally NiMH as I have plenty of those left from our son's toys which he has long outgrown) in the original battery holder be sufficient?

Regards
Max

Thanks for your question about the batteries.

The circuit is specified from 2.3V to 3.6V. Also lower voltages down to 2.0V are possible but flash write (storing your programs) probably wouldn't work with these low voltages. Remember the HP-25 indicated low Battery at <2.5V. Either 2xAA cells non rechargeable= 3.0-3.2V , or rechargable AA cells = 2.5-2.7V are suitable. I also tried my prototype with the external charger, which produces 3.3V and this will also work. If you are having lots of standby time, then so called precharged AA cells with low self discharge would be best.

The original battery holder is best for all of these.

If you are using non rechargeable AA cells you will have a slightly brighter LED display,because of the higher voltage. But as this is a Low Power version I would accept the normal display brightness and suggest to use rechargeables.

Bernhard