Building my own Jo-leklo (bug-a-beam)

Pretty cool - I actually have one of the "Dynaphos" softboxes with a mogul socket. Sort of a Photoflex Starlight knockoff, would be just the thing for one of those 400w mogul setups I imagine.
 
Another short update:

The ballast and bulb got shipped to me today. I was worried that I would have to grind down the hole in the reflector for the bulb to fit in, but thankfully it fits just right!

Tomorrow I am going to get the rest of the supplies I need at home depot and Ack Radio here in town (an awesome spot if you live in Atlanta) and try and build it! I will be sure to take pictures along the way!
 
JPM Photography said:
I did some testing on the ballast and bulb the last couple of days and turns out it is hot restrike! Great news!!
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And buying info for those parts - sounds cool. By the way, the Dynaphos softbox stuff was from an ebay vendor that doesn't seem to be around any more. They do turn up there, they're photoflex starlite knockoffs to some extent - mogul long-form bulb, tungsten, 500 & 1k watts, (just like the mogul HIDs out there) that pokes way out into a softbox.
 
So I have been on a 6 day TV show pilot that kicked my butt, sorry for not responding sooner.

We had some issues with the jo-leko, so I am going to have to do some more testing. I think it may have to do with the header cable I put on it (12ft from the ignitor)
 
If the unit doesn't have an external ignitor (which it sounds like is the case) or ignitor is internal to the ballast, you normally can't have a head to ballast cable over about 3 feet. We have experimented with using low capacitance cable however on our units and we have gotten 15 feet with no problem so that does help but as always, it depends upon the ballast itself.
 
Cool Lights said:
If the unit doesn't have an external ignitor (which it sounds like is the case) or ignitor is internal to the ballast, you normally can't have a head to ballast cable over about 3 feet. We have experimented with using low capacitance cable however on our units and we have gotten 15 feet with no problem so that does help but as always, it depends upon the ballast itself.
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Thanks for the thought Richard. The head strikes, but then, while it is warming up the arc begins to waver, becomes unstable, and goes out. Thoughts?
 
I didn't follow the whole thread, are you sure its an HID rated socket? 4000V rated or higher is really the best. 1000v would probably be fine for non-hot-restrike.

Other questions would be: how do you know the bulb and ballast are meant to work together? Did you get them both from one source that has tested them together and guarantees they work? For example, a 400w rated ballast and a 400w rated bulb won't necessarily work together just because they are 400w. Back in 2008 I experimented with lots of different combos and I realized that the 400w rated parking lot/grow type bulbs had different startup and sustaining characteristics than the 400w HMI non-hot-restrike type bulbs which are meant in projectors or spotlights. So it could just be an incompatible bulb and ballast. It might start to fire, but it won't ultimately work unless they are matched set meant for each other.

If they are a matched set and you know this because the seller sold both as working together, then I would consistently get it to fire with a shorter cable. If it still doesn't fire with the shorter cable, it must be a bad bulb or ballast (or bad connection somehow between them which includes wire and socket).

Then once that's solved (and bulb and ballast are working fine consistently), you can make the cable longer using the low capacitance type cable.
 
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Cool Lights said:
I didn't follow the whole thread, are you sure its an HID rated socket? 4000V rated or higher is really the best. 1000v would probably be fine for non-hot-restrike.

Other questions would be: how do you know the bulb and ballast are meant to work together? Did you get them both from one source that has tested them together and guarantees they work? For example, a 400w rated ballast and a 400w rated bulb won't necessarily work together just because they are 400w. Back in 2008 I experimented with lots of different combos and I realized that the 400w rated parking lot/grow type bulbs had different startup and sustaining characteristics than the 400w HMI non-hot-restrike type bulbs which are meant in projectors or spotlights. So it could just be an incompatible bulb and ballast. It might start to fire, but it won't ultimately work unless they are matched set meant for each other.

If they are a matched set and you know this because the seller sold both as working together, then I would consistently get it to fire with a shorter cable. If it still doesn't fire with the shorter cable, it must be a bad bulb or ballast (or bad connection somehow between them which includes wire and socket).

Then once that's solved (and bulb and ballast are working fine consistently), you can make the cable longer using the low capacitance type cable.
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That is the kicker. I bought the bulb and ballast together and, for the first little while it worked flawlessly, then, after the rehousing of the ballast, I sent it off to a job and on that job they said it started acting up.

Perhaps something happened to the ballast? Does this sound like an overheating problem (where the ballast overheated and now is fryed/broken)?
 
If this is a 400w ballast/bulb, cooling is really important. Below 250w, you can probably get away with no fan like we do on our 150w CDM fresnel. 250w and above, a fan is very necessary and to do without the fan really requires thought on how all the power transistors are heat sinked and some other potential issues that need to be thought about in the design of a good case. In lieu of a design where all this is considered from the start (hard to change a design to be something other than it is), at the very least, you may need a dialed down fan that is as silent as possible so at least some air is moving across the power transistors. Hard to say if its fried permanently. If its acting different than before when it was in the other casing with the fan it could be that some component is fried or it could be that some component isn't properly heat sinked now and putting it back like before might make it work ok again. Hard to tell. Also some power transistors may have a silica or silicone insulator behind them. This helps transfer heat to the casing but also insulates the transistor from shorting out to the casing. If there are some like that and they no longer have the insulator or the casing is touching and shorting now somehow, that could be a big problem.

Better to go back to the original design and try to get it working again or get another one and be sure its all working, then put a speed control on the fan (fairly easy circuit like a light dimmer) and dial it down till its acceptable.
 
I've got some 120v computer fans that are just whisper-quiet on full (used them on some tube audio gear in recording situations). I imagine dialing them down with some sort of resistor combo would make them even quieter. Main thing usually, is isolating the fan from the casing with something like rubber grommets as washers - that seems to kill sympathetic vibrations that give some humming buzz.
 
The larger the fan the better to keep things quieter. In addition to being dialed down to very low speed, we put a kind of baffle in front of the fan on our 575/1200w ballast (the only product we have that has a fan). This forces the air to exit from the sides rather than straight out. Its an old trick on the ventilation heads of air conditioning ducts in some film and TV studios that makes the air go out a 90 degrees rather than straight down and this helps quiet it down a bit so you don't hear the rush of air so much.
 
All good thoughts. Thanks everyone.

And thank you for being so involved Richard. It is great to see sponsors that are so helpful.
 
I've got a whole closet full of ballasts from my experimentation days. Most are totally unsuitable for the kind of stuff we all do. Some are dead too, from trying different things. Its just part of the process unfortunately.

Let us know how things go...
 
Curious to hear if you've got any updates on the HMI lantern idea - I'd be really interested in concocting something along those lines myself...
 
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