As far as max safe voltage, the MOV is either a 10V or a 14V trip part
(I believe based on the part number - I could not find an exact
datasheet) and most caps in the power input path appear to be 16V.
It is a switching supply, so the higher voltage is likely to never reach
the truly sensitive components. The computer is on the other side of a
transformer. The failure would be the MOV clamping and caps on the input
side bursting.
9V is probably as far as I would suggest pushing it. The NiCd, I am not
sure about. It is charged with just a diode and a resistor directly tied
to the power input. The diode is not a zener, so the battery is seeing
nearly the full voltage at the power input. But even at 9V, assuming a
.7V diode drop, it is getting about 4.5mA of charge current. I don't
want to promise it will be ok at 9V, but for short duration, it would
probably be fine.
The original adapter was unregulated, so it probably outputs in the 7V
range unloaded relying on the M100 power supply to pull it down to 6V or so.
Speaking of which, I wonder if some switching power adapters could muck
things up. If the ripple gets mixed in with the oscillation frequency of
the M100 supply, it could cause problems. A higher quality adapter will
probably be in the MHz and be too fast for the components which would
essentially filter it out. But down in the khz range, it could
potentially interfere, especially if the ripple is significant in a
cheap crap supply. Probably best to stick to an unregulated supply like
the original. The ones I had bought previously were from Jameco.
https://www.jameco.com/z/DDU060120RG2401-Jameco-ReliaPro-AC-to-DC-Wall-Adapter-Transformer-Single-Output-6-Volt-1-2-Amp-7-2-Watt-2-1mm-Plug-Center-Negative_220943.html
On 10/28/2025 4:08 PM, B9 wrote:
I tried my 5W, 5V solar panel with a Tandy 200 and it didn't work. It
would show activity on the LCD but never made it to the menu before
freezing up.
Could be because it was a cloudy day and through a glass window. Could
be because it doesn't output anywhere close to "5W".
It's too bad, since the panel is only a little larger than the Tandy
200 and could easily have been mounted on the lid.
--b9
On October 23, 2025 6:45:27 PM PDT, B9 <[email protected]> wrote:
Very cool! I remember hearing about that guy but didn't know he
had a Model T. The article mentions he had "a 12V battery, and a
five-watt solar panel."
I'm presuming he used the solar panel to charge the battery and
then used the battery to run the Model T.
"Direct solar" as AbortRetryFail mentioned might be possible, but
I'm not sure what the advantage of that would be. I think I've got
a 5W panel, so maybe I'll give it a shot just to see.
--B9
On October 23, 2025 3:48:40 PM PDT, Mike Stein
<[email protected]> wrote:
A solar powered M100...
https://bikepacking.com/plog/steve-roberts-computing-across-america/
On Wed, Oct 22, 2025 at 2:53 PM [email protected]
<[email protected]> wrote:
What are the limits/parameters of the 100's power supply
circuit anyway. Has anyone dug into it?
Direct solar power for example would be cool, but I'd be
reluctant to experiment on the 40 year old hardware...
On October 21, 2025 4:20:27 PM EDT, Scott McDonnell
<[email protected]> wrote:
This shouldn't be a problem.
On 10/21/2025 10:24 AM, VANDEN BOSSCHE JAN wrote:
I found some stabilized power supplies, discarded but
new.
They are not compatible with the models T, but I
suppose I can always adapt the pin. I’ve done it with
USB-cables too.
But these are 7,5 V, 650 mA. Isn’t that too much ?
AFAIK, a standard Tandy wall-wart is 6V, but not
stabilized.
**
*Jan-80 @ work*
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