Power sources

General discussion about calculators, SwissMicros or otherwise
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Yorkie
Posts: 1
Joined: Thu May 14, 2020 11:15 am

Power sources

Post by Yorkie »

Does anyone know of a small power bank that does not cut out when it senses the low power draw of the DM42?
hoverbeek
Posts: 17
Joined: Sat Sep 21, 2019 3:54 pm

Re: Power sources

Post by hoverbeek »

Why would you want that?

The DM42 does hardly draw any power. So the battery lasts for years.
I am still on my factory delivered battery.

Expect to change the battery once every few years.
DM41X SN: 00070 DM42 SN: 00754
HP35, ..., HP67, HP41(C,CV,CX), ..., HP48GX, ..., HP33S, HP35S, WP34S, WP43S
EM41
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Location: Overijssel Netherlands

Re: Power sources

Post by EM41 »

I have an old 2500mAh Xtorm powerbank for the DM41X, never tested with the DM42.
Mainly for use in the train when I want some more speed than with the built in battery.
Maybe the newer models are more intelligent and cut out with low power drain but the old one works well.
HP41C (2x), HP41CV, HP41CX, DM41X β, DM41X, DM42, HP11C, HP48G, HP97
dlachieze
Posts: 257
Joined: Thu May 04, 2017 12:20 pm
Location: France

Re: Power sources

Post by dlachieze »

Yorkie wrote:
Thu May 14, 2020 6:46 pm
Does anyone know of a small power bank that does not cut out when it senses the low power draw of the DM42?
Voltaic Systems is making such power banks with Always-on mode.
There may be other manufacturers.
DM42: 00425 - DM41X: β00066
hoverbeek
Posts: 17
Joined: Sat Sep 21, 2019 3:54 pm

Re: Power sources

Post by hoverbeek »

The DM41X has the same hardware as the DM42.
DM41X SN: 00070 DM42 SN: 00754
HP35, ..., HP67, HP41(C,CV,CX), ..., HP48GX, ..., HP33S, HP35S, WP34S, WP43S
grsbanks
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Re: Power sources

Post by grsbanks »

hoverbeek wrote:
Thu May 21, 2020 4:49 pm
Why would you want that?
To boost the speed, maybe?

If the DM42 is powered by USB, the CPU's clock gets bumped up from 25MHz to 80MHz.
There are only 10 kinds of people in the world: those who understand binary and those who do not.
cdmackay
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Re: Power sources

Post by cdmackay »

hoverbeek wrote:
Thu May 21, 2020 4:49 pm
Why would you want that?

The DM42 does hardly draw any power. So the battery lasts for years.
I am still on my factory delivered battery.

Expect to change the battery once every few years.
One reason to use a power-bank might be if you want the faster operation whilst running from USB power?

My naive use doesn't need that, but others' might :)

edit: sorry, Godwin, beat me to it :)
Cambridge, UK
41CL/DM41X 12/15C/16C DM15/16 71B 17B/BII/bII+ 28S 42S/DM42 32SII 48GX 50g 35s 30b/WP34S Prime G2
& Casios, Rockwell 18R :)
hoverbeek
Posts: 17
Joined: Sat Sep 21, 2019 3:54 pm

Re: Power sources

Post by hoverbeek »

Ok, faster operation makes sense!
DM41X SN: 00070 DM42 SN: 00754
HP35, ..., HP67, HP41(C,CV,CX), ..., HP48GX, ..., HP33S, HP35S, WP34S, WP43S
reavy
Posts: 46
Joined: Tue Feb 06, 2018 9:08 pm
Location: Phoenix, AZ

Re: Power sources

Post by reavy »

Many existing battery packs have an always-on mode for low-current devices. Unfortunately this functionality is often not documented. For example, some Anker battery packs have an undocumented always-on mode that is activated by simply pressing and holding the power button until a light turns green.

Some people have made USB dongles with a simple switching current sink that draws 50 mA or so for half a second every few seconds to keep the battery pack switched on. Should be Googleable.
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