My finished homewound/made ferrite HF HVAC transformer

Platinum, Fri Dec 14 2018, 04:05PM

Hello everybody after two attempts to make a suitable bobbin to slot over my UK bought 60x55x15 U cores (129x55x15 O/A) I have now had some success, The bobbin was machined by a work collegue from ABS plastic, after using black nylon I discovered this wasnt a suitable insulator. Dimensions are;

Outer diamater 57mm (to suitably sit inside the core away with decent spacing from the primary)

Inner diameter is 21.5mm (as the core is 15 horizontal length would calculate to 21.2132034) I would show the calculation but have never done calculations on HTML

Wall thickness increased to 5mm

Outer minor diamater is 31.5mm

Height is 78mm to sit inside the core

3mm radial slots of 12.5mm depth, around 5-6mm of this depth is used by the windings.

Secondary turns was a complete guess maybe 400-600

Using a safe 12 primary turns I'm getting quite some output, maybe 10Kv at 100ma, I have not tested output or input powers as of yet, will do by later this evening.

At 250khz voltage is estimated around 45Kv, it can jump around 15mm. When at 35khz voltage can jump 5-6mm, according to air breakdown voltage this would be about 15-18kv


This transformer is running from a fullbridge which powers a ferrite toridial core, using rectified mains, I have wound 11 turns for 200volts (under highest tested load so far) into the homemade transformer which uses 12 turns.


I just have one question, I need to calculate a tesla coil MMC, using all the internet calculators I have come to conclusion that they will not work for a HF transformer, any advice?



I have also finished winding the tesla coil (by hand...) using PVC drain pipe 110OD, 1150 turns as 20-80 unraveled before lacquer.





Sorry for the video, it is a little out of proportion, The green box is about 200mm X 140mm x 60mm