mab1 said  

Hi Mike,
Regarding the chinese board: apologies, I didn't mean to add to your workload - for the small price of another board i may as well just get one, and when i eventually look at it i can post here for feasability and advice (unless you really want to do it of course   ).

I will not promise anything but I am curious to see what might be required to make it work with a Nano controller.

Re postage to UK I will check into it and the customs forms etc required & cost.

There are other solutions available which I will discuss with you via email or PMs.

I am curious, what do you expect postage cost to UK would/might be - a rough guess is fine, it just helps clarify what method we might use.

Not sure if there are any MPPT controllers kicking around - lets see if anyone offers up a couple.  Maybe Poida has some spare.....

Thank you for the variac explanation Mike, I do have a variac here (the transformer variety) but was not sure what you meant with that word in regard to the control card.

Now, I do like to copy your ideas (I hope you don't mind) and when I saw your interesting use of a 'current type voltage transformer' for sensing the AC mains voltage I thought I'll have to try this.

So I laid out a control PCB with this instead of the original LT1638 that Poida used.
But I'm curious if this will work with the original Nano program?
I'm using your early version of the MC74AC86 gate drive BTW.

I'm not interested in many of the features your latest control card offers (have external fan temperature controllers and no need for automatic start up or a status display monitor.

I finished the PCB layout but have not sent it for manufacturing yet until I know if my original Nano works with your AC sensing or if I require a different program.

Thanks

Klaus you are welcome to email me a copy of your schematic so I can comment - in short I believe it should work with normal Nano code.

Thanks Mike, email sent to m...s@a...m.com.au
I hope this is still correct

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