Fun With A Hydrogen Thyratron

There’s something oddly menacing about some vacuum tubes. The glass, the glowing filaments, the strange metal grids and wires suspended within – all those lead to a mysterious sci-fi look and the feeling that strange things are happening in there.

Add in a little high voltage and a tube that makes its own hydrogen, and you’ve got something extra scary. This hydrogen thyratron ended up being just the thing for [Kerry Wong]’s high-voltage, high-current experiments. One would normally turn to the solid-state version of the thyratron, the silicon controlled rectifier (SCR), to switch such voltages. But the devices needed to handle the 30 amps [Kerry] had in mind were exorbitant, and when the IGBTs he used as a substitute proved a little too fragile he turned to the Russian surplus market for help. There he found a TGI1-50/5 hydrogen thyratron, a tube that has a small hydrogen gas generator inside – thyratrons are actually gas-filled rather than vacuum tubes and switch heavy currents through plasma conduction. [Kerry] set up a demo circuit with a small RC network to provide the fast switching pulse preferred by the thyratron, and proceeded to run 3500 volts through a couple of 1/4-W resistors with predictable results. The video below shows the fireworks.

Can’t get enough of the thyratron’s lovely purple glow? We’ve seen it before on this beautiful old switch-mode power supply. The versatile tubes also helped rebuild the first vocal encryption system.

Continue reading “Fun With A Hydrogen Thyratron”

Open Source High Power EV Motor Controller

For anyone with interest in electric vehicles, especially drives and control systems for EV’s, the Endless-Sphere forum is the place to frequent. It’s full of some amazing projects covering electric skateboards to cars and everything in between. [Marcos Chaparro] recently posted details of his controller project — the VESC-controller, an open source controller capable of driving motors up to 200 hp.

[Marcos]’s controller is a fork of the VESC by [Benjamin Vedder] who has an almost cult following among the forum for “creating something that all DIY electric skateboard builders have been longing for, an open source, highly programmable, high voltage, reliable speed controller to use in DIY eboard projects”. We’ve covered several VESC projects here at Hackaday.

While [Vedder]’s controller is aimed at low power applications such as skate board motors, [Marcos]’s version amps it up several notches. It uses 600 V 600 A IGBT modules and 460 A current sensors capable of powering BLDC motors up to 150 kW. Since the control logic is seperated from the gate drivers and IGBT’s, it’s possible to adapt it for high power applications. All design files are available on the Github repository. The feature list of this amazing build is so long, it’s best to head over to the forum to check out the nitty-gritty details. And [Marcos] is already thinking about removing all the analog sensing in favour of using voltage and current sensors with digital outputs for the next revision. He reckons using a FPGA plus flash memory can replace a big chunk of the analog parts from the bill of materials. This would eliminate tolerance, drift and noise issues associated with the analog parts.

[Marcos] is also working on refining a reference design for a power interface board that includes gate drivers, power mosfets, DC link and differential voltage/current sensing. Design files for this interface board are available from his GitHub repo too. According to [Marcos], with better sensors and a beefier power stage, the same control board should work for motors in excess of 500 hp. Check out the video after the break showing the VESC-controller being put through its paces for an initial trial.

Continue reading “Open Source High Power EV Motor Controller”

Repairing and Adding Bluetooth Control to an Induction Cooker

When his 6 years old induction cooker recently broke, [Johannes] decided to open it in an attempt to give it another life. Not only did he succeed, but he also added Bluetooth connectivity to the cooker. The repair part was actually pretty straight forward, as in most cases the IGBTs and rectifiers are the first components to break due to stress imposed on them. Following advice from a Swedish forum, [Johannes] just had to measure the resistance of these components to discover that the broken ones were behaving like open circuits.

He then started to reverse engineer the boards present in the cooker, more particularly the link between the ‘keyboards’ and the main microcontroller (an ATMEGA32L) in charge of commanding the power boards. With a Bus Pirate, [Johannes] had a look at the UART protocol that was used but it seems it was a bit too complex. He then opted for an IOIO and a few transistors to emulate key presses, allowing him to use his phone to control the cooker (via USB or BT). While he was at it, he even added a temperature sensor.