Nick,
I have not checked the circuit but I imagine the atu circuit works at the voltage level of the battery and not the supply.
The external power is used to charge the internal battery, so it supplies the charge circuitry (same as your phone, laptop etc.). ?The battery then powers the atu circuitry.
Additionally I think if the battery is flat, the output voltage from the charge circuit can then power the atu circuit directly (while also charging the battery).
Matthew
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On 5 Jul 2022, at 04:07, Nick Watling <watnickling@...> wrote:
?Hi all. Just joined group today. I have an ATU-100 and am confused re the power requirement. The info says 10-15 volts dc range but the internal battery is a lithium 3.7 volt. The input on the schematic by N7DDC shows 12volts with a 5 volt regulator
downstream. This seems logical. But-----
How does a 3.7 volt battery allow the unit to work when the supply is quoted as 12 volts?? Nick. VK4YT.
