Guru
Joined: 21/06/2018
Location: AustraliaPosts: 1156
| Posted: 12:31pm 05 Mar 2024 |
In Nano Rev5 the controller PCB could be configured to run as a Variac. This was when Poida offered to help me with some code and the Variac now runs really well.
It has an AC volts and AC current readout as well as DCVin and a programmable AC current limit which operates smoothly to reduce the output voltage smoothly, if the load increases past the current limit point.
The Variac can run from 24V or 48V or 72V just put in the right voltage toroid and a suitable choke and it just works. Perfect for a standby inverter that can run a fridge or two and soldering iron so you can fix the big inverter.
I will use it to fix an ornery 100W RMS per channel amplifier that runs great and then suddenly it stops and the output darlingtons are dead yet again (another $25 for the pair each time) it is not runaway but no warning gallop away. It needs normal mains voltage power to run, but if I set the Variac's current limit just a tad above the operating power required I reckon if the runaway starts the current limit of the Variac will catch it and save the output stage. If it still kills them its heading for the dump!
To go with this creation I made a smaller power board using 1oz copper it is 100x100mm and uses 8 x HY5608 Fets. Mounted directly above it is the CAP board which also has the FET driver buffers and optos. It is plug compatible with a Nano inverter controller or Variac controller. Power should easily be around 2kW. The cost of the 3 boards required is really cheap. You get 5 sets of PCBs, enough for 5 Variacs for under $20 delivered.
I need to redo the PCB for the Variac as I decided not to compromise the Rev6 inverter controller design for a dual purpose variac/inverter controller. It is a minor task
which will be done in a week or so and the Variac board will be a single purpose PCB.
Edited 2024-03-05 22:35 by wiseguy