As I mentioned in an earlier post, I am under the impression that the SIDAS units use TIME as the heat control mechanism.
Low is perhaps 30% duty cycle, Medium may be 70%, with High just switched ON. All at battery output voltage.
I could be wrong.
Would a simple circuit around a 555 timer and a capacitor accomplish this?
I'm no EE ;-)
SIDAS heaters for the feet
HEATING ELEMENT/TOPCOVER – Sidas USA
Special plugs molded to the ribbon cable. Some adapter would be needed to make the jump to USB
Inspecting a set of the above referenced heater elements, Only Two wires in the five pin plug are populated
13 Ohm resistance end to end through the heating elements.
E= I^2 R
5= I^ X 13
.6 amps?
3 watts? (Check my math)
Enough to burn? IDK
ETA
A quick probe of a SIDAS battery pack with the DVM.
SIDAS Nuvo Battery packs output at 3.3 V
Heat output is controlled by TIME as I had gathered. Three levels,
I did not put the output on the scope, but the low and medium settings show rather rapid changes in voltage between a few mV and 3.3 V. On/Off time ratio, I could not discern by eye.
High setting is continuous power at 3.3V.
So A 5.5 V battery stack would be TOO MUCH unless modulated. On High setting, the SIDAS foot bed heaters are WARM! Too Warm for me.