flyback cooling

[wa2ise]

Originally Posted by DaveWM

being a man of science I think I see if I can zip tie on a thermistor to the fly on the core

Just be careful that the horizontal flyback pulse doesn't couple into the thermister leads, else the ohmmeter may get confused. And also don't create a sneak path for high voltage static discharge if you connect the DVM to it, there's a risk the meter may get zapped.

[DaveWM]

dont think I will bother with the thermistor, the experiment has proven to me the only way to really keep it under 100f is a 3" muffin right at the base. I will prob just figure a way to mount it there and leave the cage off. I am not worried about fire as I never leave it running unattended, and I assume the x rays if any are still going to be shielded by the reaming 1/2 of the cage which effectively blocks the front (where I will be viewing).

While a 12 flybeck is not that hard to comeby my CTC-5 and CTC-9 are a bit harder. I was hoping to learn about best ways to add active cooling on this set but the real target are those.

I may get motivated and build a cage with the bottom cut out for the larger fan.

[DaveWM]

I used some very thin copper clad (both sided) material to fab up the cage. It was very easy as the material would bend sharply and you can burnish in a nice 90 degree bend. holes and cut outs are easy with some curved small scissors.

I folded in the tops about 1/2 inch and lap seamed with solder to hold its shape.

I still need to fab up a top, but will wait on that until I test it out.

cut a large round opening that puts the fan right at the side of the fly, used some silicone dabs in the corner of the fan to hold it in place, spaced up the fan just a bit from the copper (I am hoping that will keep the vibes from the fan from being amplified by the thin copper).

I will take some pics tomorrow after the silicone has a chance to setup. I only have about 1 hr total fab time into it so if it does not work its no big loss.

I will still have to make up a DC power supply, I think the filaments would be fine with a 1/2 wave and a 100uf filter cap.

[DaveWM]

I could not wait, the silicone had set up enough to hold the fan so I installed the cage and hooked up a 9v battery.

Its very quiet

when the HV comes up the fan slows down, perhaps the fly is effecting it, like when the neon bulb lights up near the tire.

the air is restricted by the close fitting back, I can put some spacers on the cage that should keep at least some clearance for air to get by, but its not ideal, and there is no real good way to mount it as one side sits next the horz out tube, one side is against the side wall and one side is on the back. I may have worked better if I just mounted it on top and aimed it down but I liked having the fan right up near the fly.

[DaveWM]

ok not gonna work, I had some arcing from the fly to the fan, that can't be good and the fan does slow down a LOT that close the the tire.

so its back to mounting the fan on the top and just letting it blow down. so will try that again.

[Charlie]

Originally Posted by DaveWM

I had some arcing from the fly to the fan...

That would certainly slow me down!!

[DaveWM]

yea you could hear the fan slow to about 1/2 speed as the HV came up, yikes.

I think keeping the orig cover with the top off and a sheet of mylar to guide the air downward may work as well. Other sets with more room would prob work fine, like my CTC-5 which has the top of the cage that can be removed and has plenty of space for a fan.