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Tuesday, 7 October 2025

Quick and dirty coil winder

In a recent episode of Doz' Television workshop, I diagnosed line output transformer (flyback) transformer failure in pye TV. 

So, a means of repairing the transformer was required. 


First things first was to get the old transformer apart, which was a messy and long-winded job. I'll spare you the details here...

Then what was needed was a means of counting the number of turns on the existing transformer. I didn't fancy the job of doing this by hand, so a plan was hatched.

You'll need:

A PCB vice.. I used this type, which you can obtain via the internet in all the usual places.







A length of 5mm diameter rod or bar. I started with a short (100mm) length of aluminium, but changed it to a  longer length (250mm) of stainless later on.

Some 3D printed parts: These are available for download on my git for this project here.


Two "pizza slice" shaped parts (quadrants)








One spindle 


















a handle
 








and a sensor holder 









Also needed are some slotted photo interruptors. I got these from amazon. You'll need two.









and finally a 16X2 I2C LCD display and an arduino or equivalent. I chose a Sparkfun pro-micro.

 

After assembling and fitting the 3D printed parts together, I found out that the PLA I'd printed the quadrants from passed infra-red, so I stuck some aluminium tape on the relevant areas to obscure the infra-red. I also moved the quadrants for they were 180 deg apart.









During the winding process, I made a spool-holder in a similar manner, using some of these couplers to clamp the wire, and a spring retrieved from the original PCB vice to keep some tension on the reel of wire.






You can see how it all went here :








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