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Power supply is now finished

A project log for Fun with CRTs

Because why not?

floppidydingoFloppidyDingo 11/02/2016 at 00:313 Comments

I have finally gotten the tub to light up, which means the PSU is done and I'm ready to move on.

Since the tube is miniature, the voltages needed to run it are smaller than a normal tube would take (much smaller than what I was expecting). The heater is running at 5V, if i were to go any higher the dot would fade away after a few seconds. The accelerating anode is at around 50V, and the EHT is around 1500 - 2000V (I wasn't able to get an accurate reading with my multimeter). For now I have the cathode tied to ground, but I will eventually attach it to a transistor for video and brightness control. Here is the entire unit without the case:

The entire system takes in 12V from a molex connector, and I will also add a barrel jack so the unit can be powered from the wall. Here is a close up of the power supply:

As you can see, the flyback driving transistor needs a fan to keep cool. Without the fan the transistor gets up to 90C, with the fan it sits at around 35 - 40C. There is a thermistor on the heatsink because I'm adding a thermo regulated fan controller, since that thing is noisy stuck at full speed. I also had to add my own primary to the flyback since the built in one is being picky, it might be shorted.

Next up I'm going to work on the cathode control and then the deflection coils. Also sometime soon I'll post schematics of the entire thing, so keep an eye out for that.

Discussions

Ted Yapo wrote 11/03/2016 at 02:18 point

Back in my college days, I had an old B&W TV with the deflection coil leads brought out to binding posts at the back.  I used to hook them in parallel with my stereo speakers for an ancient version of what mp3 players would call "visualizations" these days.

I was always leery of the HV inside there, though.  I think I waited a week between unplugging it and opening the case to let the caps decay.

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FloppidyDingo wrote 11/03/2016 at 02:53 point

Wow, that sounds very cool! And about the HV caps, the tube I have doesn't have capacitors directly on the HV wire. The tube itself acts as a capacitor, and it's not very good at keeping a charge. It will usually dissipate within five minutes. Whether that's good or bad for the tube is beyond me, but it's good for my safety.

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Eric Hertz wrote 11/03/2016 at 00:20 point

brave!

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