Tessie – Early test bed for SSTC’s

Tessie
Tessie is a test bed for a SSTC.
It was built so that the components could be easily exchanged for others and therefore was not built on a single pcb. This of course makes its own problems.

Basically the design of Tessie (at the moment) is bridge rectified and smoothed mains is passed to two banks of three IRF840s each with a large snubber circuit. The output of the two sets of IRF840s then drive a 10-0-10 centre tapped primary.
The drive for the MOSFETS comes from an MC4060 PLL oscillator at around 1800Khz which is sent through a flip flop to give inverted and non inverted gate drive outputs at around 900Kkz.
There are various circuits that will detect and limit the current through the mosfets and turn off the drive if over current is detected. (and one day Ill get them to work).
The secondary is 18 of  0.25mm wire giving 1300 turns on a 2.5 former. The Top load is either of two 8 discuses covered with aluminium foil or two 8 stainless steel mixing bowls from ikea taped together with aluminium tape.

When it is running 4-5 arcs (poor) can be drawn with huge power (around 500W), a flame appears on top of the arc and it eats the aluminium foil coating off the top load. Unfortunately I have only been able to get this for very short periods of time due to excessive current being drawn by the mosfets.
At present the design runs either in CW or at 50% from a 1Khz oscillator.

Improvements: Slow start, Start up at full power blows the mosfets.
PWM power control , a method of controlling the power is urgently required or a variac must be acquired.
Experimentation with different primary coils to adjust the primary-secondary coupling.

Project Scrapped Due to the driver and mosfet arrangements being not suitable to teslacoil driving, hence many of the above problems. Components to be used elsewhere.
File:https://www.extremeelectronics.co.uk/old/coils/tie/tessie.php