What shielding is needed between two transformers in a confined space?

Thread Starter

CAB55

Joined Nov 24, 2020
21
I have a DIY spot welder project that I have completed the mechanics on and now trying to incorporate some control electronics into the remaining confined space. I have to add a 9 V AC transformer to power a control board and subsequent 5 V DC cooling fan. based on the pictures provided, any recommendations on what should be done to shield the boards and or transformers?
FBEAAD7C-D08C-401D-8D4F-9FCD1C978FE3.jpeg96759268-ECCB-478A-8748-6D930C2B359A.jpeg28A7710E-4659-48D8-B2F4-91EC3CFB7ACB.jpeg388A881C-C261-4DEC-8152-3241298B87CC.jpegThanks CAB55
 

MaxHeadRoom

Joined Jul 18, 2013
23,945
The transformer and board appears to be within the throat of a spot welder, not an ideal position!
Max.
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
23,945
But It is unknown as to how the effect of several hundred amps in the area that the circuit is going to affect or be imposed in the circuit, transformer etc?
Max.
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
The transformer and board appears to be withing the throat of a spot welder, not an ideal position!
Max.
Agreed. Unfortunately the original project did not include the electronics and there is not enough room in the rear. I furthered my education since I started the project and want to be able to control the exact time and current. I suppose I could add a box on the outside of the housing that could house all of the circuitry if you feel it is necessary??
 

dendad

Joined Feb 20, 2016
3,939
You may not need to shield the transformer at all. But if there are problems, one thing you could try is to lay the small transformer on its side so the coils of the transformers do not share a common plane.
A test you could do is to disconnect the small transformer and measure the AC volts on the primary winding that is induced into it from the large transformer and rotate tha small transformer until you get a minimum reading.
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
You may not need to shield the transformer at all. But if there are problems, one thing you could try is to lay the small transformer on its side so the coils of the transformers do not share a common plane.
A test you could do is to disconnect the small transformer and measure the AC volts on the primary winding that is induced into it from the large transformer and rotate tha small transformer until you get a minimum reading.
That’s a great idea dendad! I have not secured anything yet so I will try this. Thanks for taking the time to reply. I love this industry and the people in it!
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
Id also use a steel shield, not aluminium
I’ve already constructed the spot welder within an aluminum housing, does this create any problems that you are aware of? Also, should I be covering the boards in a steel mesh to create a Faraday cage?
 

Deleted member 115935

Joined Dec 31, 1969
0
A faraday cage is fine in aluminium,
I was more concerned with magnetic field of the large Pulse of DC the spot welder gives out,
If you have sensitive electronics, they will probably need shielding,
hard to say, its a very much an art form.
Have you made the board with good shielding built in , and plenty of ESD / EMI filtering ?
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
A faraday cage is fine in aluminium,
I was more concerned with magnetic field of the large Pulse of DC the spot welder gives out,
If you have sensitive electronics, they will probably need shielding,
hard to say, its a very much an art form.
Have you made the board with good shielding built in , and plenty of ESD / EMI filtering ?
Pardon my ignorance andrewmm as I am new to the world of electronics but am educating myself on all aspects daily! It’s such a fascinating field with many grey areas I’ve found, this being one. I was not aware of the ESD/EMI diodes. I am attaching 2 more photos showing the 2 boards I plan to use. One to control a 5v DC fan, did not have a breadboard so used some simple connectors to test the circuit. It delivers 4.99 v DC. The other (just purchased) to control the spot welder’ time and current, which I hope to mount opposite to the other. I will also be adding a foot control, which I twisted up the cord wires instead of using shielded cable. I am totally open to any further criticisms or suggestions. Thanks CAB55E22F8A7E-F2AC-4CC1-8F53-6E7C94A8A5ED.jpeg7D942673-6E73-4C5E-BE14-83888B3BDD78.png
 

MaxHeadRoom

Joined Jul 18, 2013
23,945
OP = Original Post.
Seems a little overkill, the majority of spot welder controllers I have worked on just used a energized time for the spot duration control of an AC waveform. i.e. transformer primary.
If a smaller duration for a fraction of a AC cycle, the primary is Triac pulsed.
Max.
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
OP = Original Post.
Seems a little overkill, the majority of spot welder controllers I have worked on just used a energized time for the spot duration control of an AC waveform. i.e. transformer primary.
If a smaller duration for a fraction of a AC cycle, the primary is Triac pulsed.
Max.
Ha! Ha! I’ve been so overwhelmed with learning so many electronic abbreviations that I thought “OP” was one I hadn’t come across yet! This project is overkill but I thought it would be a great project to challenge and educate me on dos and don’ts moving forward. I appreciate your guidance and wisdom Max!
 

Deleted member 115935

Joined Dec 31, 1969
0
The EMC / EMI parts and shielding mentioned ,
are all about reliability .

Its a grey area, but you can build without worrying about it , most of time it works .

This site is a good background, but you can quickly drown..

http://learnemc.com/emc-resources

Good luck.
 

Thread Starter

CAB55

Joined Nov 24, 2020
21
The EMC / EMI parts and shielding mentioned ,
are all about reliability .

Its a grey area, but you can build without worrying about it , most of time it works .

This site is a good background, but you can quickly drown..

http://learnemc.com/emc-resources

Good luck.
Ha! Ha! I’ve been doing a lot of drowning lately. There is quite the sea of knowledge out there for sure! Thanks Andrew, I will check it out for sure.
 
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