My freind Rick, along time ago, gave me his old PC. It was a P4 in a server case and a huge Dell monitor. He had nick named the duo “The Widow Maker “. It was a fitting name.
Today that P4 has a new case and a new life at my sisters and is still going strong. But the 100lbs CRT monitor had been dying a slow death for a long time, and I finally decided to put it down.
Instead of just sending it to the recycler, I wanted to get as many parts out of it as possible.
The Widow Maker had a peaceful death, the last wish she made was to be reborn in a new form. So i started taking out organs and thinking of how to reincarnate The Widow Maker.
What parts did I get out of this beast? A whole lot of heatsinks, an AC filter for 120V/250V, some little glass bulbs, which I am trying to identify, a bunch of transformers and chokes, and the prize find of the day…… a decent size flyback transformer (to be expected in a CRT). Seeing that flyback transformer got me thinking. High voltage = fun! My thoughts went to plasma speakers or a tesla coil or a HV capacitor charger for a larger coil gun. But that thinking led to how the hell do you drive this thing?
so I got out my dremal and some scrap wood to make a base for this.
I just drilled out enough wood for this to sit nice and flat. also for saftey reasons, I needed a non conductive base.
My driver I decided, was going to be an MSP430G2231, a generic transistor and a power mosfet (22N50 what i have on hand) a few resistors and a diode. Why did I choose a uC with an adc? I wanted to be able to make a varible PWM drive where I can change the frequency and duty cycle to choose the best combo to get the most voltage out of this device.
My first test was to find the pins connected to the primary coil and which one was the feedback coil. On this one it was pretty easy, you can see the coil wires soldered to the pins and you could tell the primary coil by the spacing of the pins.
The pins on the right I have no idea what they are connected to, multimeter test reveiled no connection to any other pins and the pcb traces dont give much info either.
There are also 2 other wires and 2 other controls that are labeled focus and 2, my guess its for some other part of the CRT that needed HV, but not not as high as the main HV wire.
My drive circuit
With this setup my mosfet gets very hot, really quickly, even with a large heatsink. Good thing I harvested some large heat sinks.
and here is the first video of the testing.
There is a lot more testing and tweaking to do. More to come!
As for the code for the chip, its nothing special but it will be coming in the next post.