Guru
Joined: 21/06/2018
Location: AustraliaPosts: 1106
| Posted: 04:36am 18 May 2024 |
Ok the Variac boards are back, I built one up and it seems to work superbly first time.
I have a pretty good energy meter which gives RMS volts Amps and true Watts.
Once calibrated, the Variac V & A tracked the energy meter within 10mA (only up to 4A tested) and 1V. The 1 V is because it only has whole digits no decimal places but even 1V in 240 is about 0.4% or better, from a setting of a few volts to 240V very accurate.
I plugged in an inductive type Fan that showed 230mA of current but the energy meter has it as 200mA so as predicted the accuracy for reactive loads will be poorer, resistive loads should be spot on.
The offset at the bottom end for V & A can be tweaked when calibrating for best accuracy. ie set the volts to a few volts and tweak the offset so it reads the same as the reference meter and then check the top end again and as needed enter the max value in the on screen menu.
So time to call for interest in sets of PCBs - I have the following shows of interest to date. If there are any changes to the list its fine just let me know. I expect that I will give it at least a week or so before placing any orders. In the interim I will prepare the BOMs etc with all the final component values - the original BOMs are still 95% accurate - a few added parts and a few resistor value tweaks though.
I will also post final schematics and BOMs etc in a couple of days - have some other tasks to get done first so maybe Tuesday.
The board sets and part numbers are as described near the bottom of page 4 of this thread.
Member name Given Name Inverter Variac Controller only
KeepIS Michael 1 3
Disco4now Gerry 2 1
Cobbler Michael 5
Bryan1 Bryan 2 1
RogerDW Roger 2 1
mab1 Marcus 1 1
PM's are probably the best way to indicate what you are after and the quantity.
Edited 2024-05-18 23:17 by wiseguy