Can I hack my one and only dmx strobe?

[rickharp]

For Halloween this year, I added a 750w Mega strobe similar to Amer DJ, which has the dip swithches and the DMX in and out. I am a DMX dummy, I understand it could be a dumb question but thought I would throw it out, which I already think is imposible from reading the other threads. I do NOT own a IDMX but understand it will provide me what I need. In the spirit of saving some money I'll carefully proceed... since I only have a strobe to sync to lightning, I was wondering if I could control it some other way. Here is what is happening. I have the strobe plugged into a 16 channel LOR controller, and turn the channel on for about a second or two. What I think is happening, is that the strobe needs to warm up or store energy in the caps so when it gets energized it does not always flash cause the cap drained, and most of the time, does not come on at all. I guees 1.5 seconds is not enough to charge the caps. So, one instinct I had was to "hack" somehow the strobe to initiate a signal similar to what a IDMX would do.

Is there a way to short one of the dmx leads to initiate the strobe, obviously using a relay. There is a ground, date- and a date+. A $10 relay, if it works, would save me $295 for the idmx.

Thanks in advance.

[-klb-]

Not on the DMX. But, does that unit have a slave in connection? That might work with a relay, or a relay and low voltage power supply..

[edvas69]

You may want to see if the dip switches allow you to run in test mode without DMX, usually dip 10 does this. Then just turn the unit off and on from the relay. I did this with a strobe unit and controlled it with the LOR board.

The other thing is to compoensate in your sequence where the times the strobe is slow as the caps have to charge and see if it gets closer to where you want. Otherwise DMX is the only way and it will give you much better control, but you will have to pay for that privledge

[Ponddude]

I would have to see the guts of the strobe but I bet it could be done...just not how you want it to be done.

I would think that the DMX would trigger some sort relay inside the strobe to activate it. You would need to get to that relay and just power it directly.

[-klb-]

The thing is it probably won't be a recognizable relay. It is probably a SCR, on circuit card. Not exactly how most people want to get involved in modifying things like this.

[rickharp]

I am fine wiht that, and was thinking the same thing. I'll post a picture of the board here soon. Thanks.

No Slave IN.

[rickharp]

Here is a picture of the strobe's insides. My instinct now is to put the relay on the leads that go to the bulb. but all that stored up power will not be going anywhere and may arc over the contact in the relay. The relay I intend to use is a very heavy one, if I recall, it is a 20 amp, 240v relay on the output side.

Anyone have a better idea. My ambition is to have the strobe come on, on que. Right now it needs a few seconds to warm up, charge the caps, but it is very inconsistent. I can't get my lor to have the right amount of time to simulate lightning. I am trying to prevent a dmx1000 purchase for $250. Thanks


Attached files

[Steven]

I don't think the relay idea will work. You need to get deeper into the circuit. If you search for "xenon strobe schematic" you will find some good references. One had this picture:


In your case, the trigger switch is probably a transistor, but you may be able to find it since it's connected to the trigger transformer. You could use a low-power relay or even a SSR across that.

It's hard to tell from your picture if that blue transformer is the trigger transformer or the high voltage supply. It's also hard to tell where the flash capacitor is, but I would guess that small silver wire is the trigger wire, which mean it must go to the trigger transformer.

Keep in mind that the xenon flasher circuit above is from a disposable camera, and it uses 350 volts! Your 750W strobe will have voltages at least as high, so be careful!

[-klb-]

Just to reiterate, there are two dangerous voltages in any Xenon strobe. The main capacitors are usually charged to 350V, and that charge may stay for days after the last use. Firing the flash won't necessarily fully discharge the caps either.

The trigger voltage is usually about 4,000V, and generated from a small high ratio transformer. Some circuits are designed such that the trigger voltage may be generated at any time, even with no power to the circuit.

Either of those voltages may be enough to kill you.

Looking at your photo, the trigger transformer is the yellow cylindrical component to the lower right. The dark rectangular blocks are the storage caps that store the energy for the flash to fire.

The other transformer is most likely part of the power supply for the micro controller (far left) that listens to the DMX signal. I will note that if this strobe allows for variable flash intensity by DMX settings, one of those big components on the heat sink may be either a SCR used to control how far the capacitors charge, or a IGBJT used to cut off the strobe before the capacitors are fully discharged. If either of those is the case, then the circuit likely won't operate correctly with just a simple trigger to the trigger coil...

[rickharp]

Perhaps I should consider the lor IDMX for $249. If I could justify some other periferals, for Christmas, then the costs may not hurt so bad. Here is a closeup of that side of the board. Still like the idea, but not if it's dangerous or hard to get to the leads. Thanks

Attached files

[Tracy West]

My strobes are set up for dmx but I can set the switches to be on auto and they work without the dmx controller. I just ran them through my LOR. I am wanting too to connect to dmx but still have a lot to learn about that.

[-klb-]

Before you dive into the iDMX for the strobe light, do check exactly what features your strobe supports via DMX, and compare them with the features you are looking for.

Most will let you pick how fast they fire, and set them to run, or stay off.

Usually the next feature added is selectable power.

The last feature usually added, to the most expensive strobes, is the ability to fire on cue. Yours may not have that feature, if that is one you are looking for.

More comments on how these work. As you saw in that prior diagram, the strobe tube is directly connected to the 350V power supply, and nothing happens as it charges up to that full voltage. That third lead, the trigger, goes to a lead that is along the entire length of the strobe tube, but not quite to the other two terminals. When the 4,000 volt pulse is applied to this terminal, it knocks a bunch of electrons loose in the xenon gas, which allows that 350V to start flowing through the xenon, knocking more electrons loose, and creating the burst of light.

[Ponddude]

You could always buy the iDMX and get some DMX stuff from me next year...hehe

[rickharp]

-klb- wrote:

Before you dive into the iDMX for the strobe light, do check exactly what features your strobe supports via DMX, and compare them with the features you are looking for.

Most will let you pick how fast they fire, and set them to run, or stay off.

Usually the next feature added is selectable power.

The last feature usually added, to the most expensive strobes, is the ability to fire on cue. Yours may not have that feature, if that is one you are looking for.

Gosh Kev, you really know your stuff! You are right, this less expensive strobe only has two channels, and they only operate the flash rate and the intensity. So,,,, how should i proceed, if at all, to have better Que control of the strobe for lightning, with an lor channel. The hack seems like a good idea, but the components seem cheap and tightly packed.

[rickharp]

Now I have another hunch. When I operate the strobe by plugging into a wall and pulling it, except for the first time, i gennerally get it t flash about 1 second after the plug in, and its consistent.

my thoughts are that if I demo it again with an LOR, simulating the same plug in cycle time as above, it won't fire at the consistent 1 second timing, because something from the LOR is different than straight from the plug. So, my thinking is, if I use the lor to power a relay, I could effectively send it straight through power, which may be cleaner or more powerful than what the LOR can provide it.

I'll try that tonight, but I think that will give me a consistent start up period from energize, that I can build in to the timing. If you recall in the above threads, using the LOR to enegize the strobe sometimes lit the strobe and sometimes did not, even giving it a lot of time before the lightning. It would either flash to many times (to long) or not flash at all.

Kev, do you like the idea of using a relay? Thanks

[-klb-]

Using a relay can't hurt. You may need one C9 lamp on the same channel as the relay coil. Some relays seem to chatter on LOR without some extra load, as the relays don't always draw enough power for smooth operation.

But, I'm not sure it will help... The challenge is figuring out how much time it takes to the first fire, depending on how long since power was last removed, and I suspect it will be about the same with, or without the relay.

[rickharp]

ok, now I've figured out my workaround, and I feel the relay is not the trick. The strobe needs 45 seconds to warm or charge up. and that was my issue, it took several very long lor cycles to finally charge it up, and the cycle was to long to look like lightning.

the procedure will be, once the show is running, plug the strobe into a hot socket to charge it, then move it over to the lor sequence. as long as there is lightning every 5-8 seconds it will basically flash on que.

I'll try it soon and reply if that works. thanks for your help.