MOT Questions (Microwave Oven Transformer)

Thread Starter

Mikeys4x4

Joined Jan 20, 2018
5
I an constructing a large insect zapper (wasp/hornet) as the store bought ones are not up to the task. Originally used a 12kv neon transf. and it effectively cooked the critter but had a runaway arc issue once the arc was initiated. While pretty, it wasn't the appropriate solution. The current attempt is using a MOT. Approximately 2200v but higher current.

Most MOTs have one end of the hv coil inaccessibly bonded to the frame. Both ends are accessible on this one. As I plan to use the microwave diodes and a pair of microwave caps to turn this into a dc source approx 4500 to 5kv I will need both ends of the coil not grounded.

The question: leave the one end bonded to the frame and insulate the HEAVY MOT from the case, or hook both ends of the hv coil (NOT bonded to the frame) then mount (ground) the MOT frame with the case?

Also shunts in or out?

The objective here is a lightning bolt that self extinguishes. I realize shunts out will increase current in/out of the MOT and I do have room to put a second MOT shorted as an inductor for limiting. Thoughts or suggestions?

Anything I am overlooking?

The objective here is to NOT maintain an arc but simply a killing arc then, next critter. I do have additional caps if the suggestion is a cap bank.
 

Thread Starter

Mikeys4x4

Joined Jan 20, 2018
5
I was not specifically referring to the TS, only a general trend among DIY'ers to find innovative(?) ways of using this particular 2nd hand component.
I simply wanted something a bit more robust than neon, lower voltage and something that capacitors were plentiful for. Back to the original post, the neon did the job, just had a nasty runaway arc
 

Rufinus

Joined Apr 29, 2020
83
I don´t know very much about electricity. What I know is MOT are very very dangerous. The current is very high. I´m sure there must be other solutions.

One question. Since MOT gives AC, and one terminal is grounded to the chasis, why I don´t get electrocuted when I touch the oven? I mean, when is AC, the circuit doesn´t have to be closed, because the capacitance of my body.
 

Ian0

Joined Aug 7, 2020
2,218
Microwave Oven Transformer
Thanks. I was guessing at "output transformer" or "microwave" but hadn't quite made it fit!
It tends to get called a "microwave transformer" but that is equally confusing as it could be taken to mean a transformer that operates at millimetre wavelengths!
The one that really confuses me is VFD - Is it "vacuum fluorescent display" or"variable frequency drive"?
 

Ian0

Joined Aug 7, 2020
2,218
I don´t know very much about electricity. What I know is MOT are very very dangerous. The current is very high. I´m sure there must be other solutions.

One question. Since MOT gives AC, and one terminal is grounded to the chasis, why I don´t get electrocuted when I touch the oven? I mean, when is AC, the circuit doesn´t have to be closed, because the capacitance of my body.
Because one side is connected to the chassis and that is connected to ground.You don't get a shock from touching ground, the other end of the high-voltage secondary connects (via a rectifier) to the magnetron, and you can't touch that.
 

Rufinus

Joined Apr 29, 2020
83
Because one side is connected to the chassis and that is connected to ground.You don't get a shock from touching ground, the other end of the high-voltage secondary connects (via a rectifier) to the magnetron, and you can't touch that.
Thanks for your answer. And does it flow current between the grounded terminal of the MOT and the earth? Sorry if a said a stupid thing
 

Ian0

Joined Aug 7, 2020
2,218
Thanks for your answer. And does it flow current between the grounded terminal of the MOT and the earth? Sorry if a said a stupid thing
No - It flows through the magnetron then back to the other terminal of the transformer (which is earthed). No current flows in the earth lead.
 

Rufinus

Joined Apr 29, 2020
83
Ahh ok ok because is a close circuit with the magnetron. Ok I see, but if the circuit were open, the current will flow to earth, right?
 

Rufinus

Joined Apr 29, 2020
83
So, if I take the MOT from the microwave ant run it, conecting one of the HV terminals to earth (ground in the socket) won´t flow current?
 
Top