"Smart" microwave

Conundrum, Sat Sept 23 2017, 03:02AM

Hi all.
Project "Nukerwave"

Essentially this is a smart microwave which is capable of adjusting its power from 0.5 to 110% or any pattern combination needed in a very precise pattern broadly similar to how a PCR machine works.

This is done by replacing the clunky mains transformer with lots of little inverters running on mains or independent battery back up and controlled by two Pi Zero W's running in master/slave quorum mode.
The software is running on both Pi's but has an LM1881 on each S-video output which is also hooked up to a viewscreen in odd/even mode. This allows me to view both units simultaneously with modified 3D shutter glasses and the LM1881 is hooked up to a 555 based reset circuit allowing one or both units to be restarted then resynced with the other in case of failure.
Also included: magnetron crowbar for safe shutdown by dumping capacitor energy through two shunted Russian power triodes.
This is in addition to other failsafes mentioned later.

The software so far is just basic Jessie but using W means I can also monitor things like magnetron leakage/reflection using the built in signal strength meter and NoIR camera feedback on the pellet/etc in addition to O2 flow rate and other parameters.
The 3D image is displayed and can be seen remotely, also by using model servo and TV colour wheel different wavelengths can be selected allowing for various experiments to be done.

4*36V Fans also controllable from software so I can run this for up to 12 hours at a time without risking overheating.

Safety (important!) I am going to be using the existing door sensors as a direct go/no go to cut power on the HV drives.
The battery backup and mains are wired through two independent relays so that both have to go on in sequence for magnetron to be enabled and the door switches also have to be locked.
There is also an additional failsafe if MW leakage over 1.5mW/cm2 detected (well beyond wifi output) that cuts main and backup power via external inline ELCB trip and sounds audible alarm.

Backup is likely to be 4 12V 3Ah alarm batteries as they fit in existing space within the sealed external RF shield.
Filament current is also monitored and can be adjusted for soft start thus increasing magnetron durability.

As also mentioned this setup can be installed on nearly any microwave but the older ones seem more robust and plus manufacturers leave a schematic on the inside casing (!) making repairs simpler.

Current status: have one W + noIR need two.
I have an original Zero here and might be able to add needed parts but lack of a camera is a real pain.
May have a candidate MW oven which is a Sharp and has a decent power output (850W) but need to retrieve it from Shed of Doom.

-Andre