A Single PCB Full-Bridge
                                                                                                 Solid State Tesla Coil

Solid State Tesla Coil 4 Platform

My SSTC 3 project turned out to be a good experience in developing my first single-PCB tesla coil. It went pretty well, but I wanted a little bit more power and had several ideas I wanted to improve upon for the design. As a result, I decided to modify the SSTC 3 to utilize SMD components, and added another half bridge to form a full-bridge for the main inverter. The result is SSTC 4 - a single PCB, General Purpose Solid-State Tesla Coil Platform capable of swappable interrupters like a graphics card on a computer, and configurable for us as a DRSSTC with the addition of a tank cap.

- Note: this page is still under construction! More to come soon.-

SSTC 4 Project Status: Tested at 120VAC and 240VAC! (Oct 2015)

*Boards for Sale*: I had a bunch of leftover boards left from the development of this project. Please see my sales page for more information.

SSTC 4 Specifications (July 2015):

- Compact footprint and mounting holes to fit and mount exactly in almost all ATX power supply cases (only because they do make for a cute box!)
- Laminated Full-Bridge topology with low bus inductance, accepting 4 of your favourite TO-247 IGBTs or MOSFETs
- Robust discrete push-pull MOSFET driver
- Commercial drop-in GDTs for easy assembly, and great performance
- Generous heat-sinking for the full bridge
- General purpose feedback allowing Antenna, Primary Current, Secondary Current or direct Secondary feedback
- On-PCB logic transformer with switch for easy dual voltage (120 or 240VAC input) operation!
- Swappable interrupters / controllers like GPUs on a motherboard - compatible with SSTC 3
- Safety protection, bleeder resistors, Under Voltage Lockout, Fuse (5 x 20mm)
- Add one resonant capacitor and an external bus cap to convert this into a DRSSTC (has flip-flop for zero current turn-off!)
- Added spade-connectors for easy external connections

 22 Sept 2015 

Project Description

The SSTC 4 single-PCB Tesla Coil was developed as a full-featured all-purpose Solid State Tesla Coil platform for building a compact yet powerful full-bridge coil, all on a single PCB. This revision was developed as an improvement over my reliable and proven SSTC 3 half-bridge platform, and builds upon it with many improvements. Full-bridge operation allows significantly more power output compared to a half-bridge.

Like the SSTC 3, the SSTC 4 platform was designed primarily to be run from the sine-wave ramp from the mains ('ramped mode'), but can be easily converted to regular SSTC operation with the addition of a bus cap, and also into a DRSSTC with the addition of a tank capacitor. The board was designed to be easy to hand-solder despite using some SMD components.


Full schematics for SSTC 4 are available here. Hopefully this will be useful to those looking to develop their own designs.

I also developed a very simple test interrupter to go along with SSTC 4. SSTC 4 was designed primarily to be run in ramped-mode like SSTC 3. This simple interrupter offers a dual functionality of a mains zero-crossing detector (via the 12V transformer) and also allows of optical input from an external controller. In order to reduce parts count, the analog staccato interrupter used in SSTC 3 has been updated to use only an optocoupler + a small Atmel microcontroller (ATtiny45/85). SSTC 4's interrupter input has the same pin-out as SSTC 3 for compatibility.

The source code for the controller can be downloaded here (source or hex).

PCB Design

Swapping the DIP packages for SMD saved me a bit of space on the PCB for the large heatsink and additional two IGBTs.

Some features include a laminated bus, multiple footprints for input/output connections, and laminated gate drive lines.


Improvements from SSTC 3 include a more robust discrete MOSFET push-pull drive for the GDTs, off-the-shelf GDTs for solder-and-play operation (no more worrying if you got the phase right!), as well as an integrated switch for both 120VAC and 240VAC universal operation.

Populating the boards

Finally I got the PCBs fabricated and I'm glad to say that it turned out very nicely, and fits almost all ATX power supply boxes perfectly :-). Admittedly, a steel ATX box is hardly the best enclosure for a SSTC operating at a few hundred kHz, but nevertheless it makes for a cute case.




Building a Coil

One of the first few coils I built using the SSTC 4 platform was a very simple and small SSTC running in 'ramped-mode' off the mains sine-wave ramp, for my friend Philip. This coil runs on 120VAC and was designed to be a simple, plug-and-play coil which could run reliably and fairly quietly as a very simple demo unit with zero set up time. As a result, the coil was not strictly optimized for performance, but nonetheless produces decent, small sword sparks and effectively serves its purpose as a good demonstration unit!

Phil helped to take the photo above of the coil in action!

More to come soon, do check back often for updates!

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(c) Gao Guangyan 2024
Contact: loneoceans [at] gmail [dot] com

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