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Adding warm up power to switching packs.

Discussion in 'Lighting and Electrics' started by Joren_Wendschuh, Jan 16, 2004.

  1. Joren_Wendschuh

    Joren_Wendschuh Member

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    I have a switched setup using solid state relays to control a set of 8 par64 (1kw) instruments, how would I add a trimable voltage to keep the bulbs 'warm' while doing chases?
     
  2. ship

    ship Senior Team Emeritus Premium Member

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    A true warmer would have the voltage range cliped so it expands 20% to 100% it's giving in dimmer range to 0% to 100% given off by the light board. Given you are using switches for all intensive purposes, it's getting difficult since when off there is no voltage to the light.

    To do this, you need to know what the heck you are doing with electricity - and I mean this. If a student, draw up a electrical diagram and have the electronics teacher if your school is so lucky approve it, otherwise the head of the maintinence staff approve it in addition to an electrician. Than the box for it also has to be approved after the diagram. And I'm not kidding about this, do not play with electrics without proper supervision. I'll fly to Hawaii and after some time on the beach kick your butt if you attempt this without supervision.

    The basics of how to do this is in making a D shape circuit. The points of the D are power in and power out and you have two hots feeding the power out. One hot goes to an in line dimmer or electronic current limiting device that is set to your desired voltage. The other leg is attached to the switch/relay. Current follows the path of least resistance. When the switch is off no current passes on that leg of power and the path of least resistance is thru the dimmer. When the switch is in the open position, it's less resistance to travel thru the switch circuit and it will flow thru it instead of the dimmer. Simple as that. On the in feed, you must fuse or breaker the component since current will always be flowing thru it, in addition to installing a master switch. Also your dimmers must be rated for the load.

    Here is the problem, lag time. Unless electronic current limitating device, solid state and highest of quality, you might or might not have problems with a certain amount of lag in going to full for the chase. Also, the constant on/off switching might damage the dimmer/limitating device. This is what you pay for in real dimmers with bump buttons and chase sequences.

    Selected reading might be some studies into how dimmers work such as a ETC Sensor rack in giving that warming circuit, the chase yet not damaging the dimmer. Than "American Electrician's Handbook" by Croft to tell you how to wire the thing safely.

    Such circuit design is not my field so my understanding of what's going to happen to the dimmer is not exact. Might be fine, might work perfectly well, but it's not my expertise. Contact a real electrician and or perhaps an engineer at Strand, ETC, Leprecon or almost any company for advice. They will probably be able to offer a lot of help on the subject out of interest and not to let you electricute yourself.
     
  3. Joren_Wendschuh

    Joren_Wendschuh Member

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    Hehe, Yes, dont you worry about my safety. I fully understand what I am attempting to do, and the potential (hah no pun intended) hazards. So essentialy, you are saying to hook the output of a dimmer circut, to the output of the "relay" (being that it is a solid state relay), directly, without any 'in between' devices? Doing it with AC there would need to be some kind of a funkey setup to keep from frying the dimmer, and to keep the output from the dimmer, from connecting the switched circuts together... would it be possible to use, a DC power supply, with an adjustable output voltage, and a BIG FRIGGAN ASS diode, connected in front of each 'switch' output, to keep seperate each switched circut? Would DC be acceptable to use as a 'pre heating current'? The DC powersupply would then have its 'ground' or 'return' connected directly to the neutral line..., the DC voltage flowing through the diode, to the instrument, through the filiment, down the neutral line. Any coments? In theory it should work.. ANd YES again, I know what the saftey issues are. Hush :p
    QUestion though, where did you come up with the idea that I live in Hawaii? Hell, Twould be a nice vacation (damn, which reminds me, I need one soon...) but uh, I live definetly upon the East coast of the USA, in a certain state, with the abreviation CT...
    Thanks!
     
  4. ship

    ship Senior Team Emeritus Premium Member

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    oops, wrong person for the location.

    As for mixing DC into an AC circuit, even on the neutral no don't do it. Bad Karma. First what about phase harmonics and unbalanced loads sending a pulsed voltage into your DC voltage neutral return line. Than it's the idea that the DC system needs to run back to somewhere because the ground probably is not going to be an adiquate drain for it. Could do this with an DC control circuit if both dimmer and switch were DC in controlling some kind of relay or dimmer, especially if you are doing analog control but after that, it's not going to be much help and your lag time will kill the effect.

    In essence we are talking about a three way switch. Both power sources are feeding off the same source. Attaching them to differing phases much less power sources would be really bad. What's to stop you from having both switch and dimmer in the open position? When the power to on, the power to the second is not important because power flows thru the switch that allows flow. When it is switched off - given there is no traveler wires, than there is no current flow. When the other path of least resistance, the dimmer is on, current flows thru it. Turn on the switch while the dimmer is running and it's easier for the current to flow thru the switch than thru the dimmer so the dimmer becomes inactive for the most part. Since it's all of the same potential there is no back feeding danger to the dimmer either. What's important however is that both switchs are gaining power from the same source. Introduce two differing sources to it and you blow up stuff when you make a mistake and switch them together.

    As for diodes and other stuff, electronics is not my field nor skill. I'm talking very baisic electrical theory here on a very simple switch. Want electronics Woemek, DMX Tools and others here and elsewhere would be much more able to help. Especially DMX tools - where are ya?

    Mix in DC control or voltages to this and it gets really complex. You might use such a thing for control of a switch but on the baisic power flowing thru either circuit A or B, you don't want to mix DC into the equasion. In other words, you don't want DC power anywhere near your lamps unless your whole system is DC and it has lots of it's own problems especially with voltage drop. You mix power sources by accident or anything else and you have things blowing up. No, unless you had some kind of pause type switch between power sources such as an On/pause/on type switch it would be a bad idea. You would have to have a switch that switched both hot and neutral for both types of power in the same instant and had a pause between such currents flowing thru the line so it did not damage itself much less cause other problems. Draw it out see the problems. In general however avoid sending DC power down any line, even a short could really ruin your day for all other gear. It would be nice to just send a 12VDC current down the line but it's not good to think about past the NO. Even feeding a 12v AC transformer in place of a dimmer would be bad because in that case you just might back feed the transformer.
     
  5. DMXtools

    DMXtools Active Member

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    A relay pack is basically a simplified dimmer pack - and leaving out the "keep warm" circuit is part of the simplification. Adding a keep-warm circuit wouldn't be too difficult...IF I had a schematic of the particular relay pack you're trying to modify. Probably take a capacitor, a diode and a couple resistors per relay channel. Need to see the circuit in order to figure out exactly where to hook them in and what values they should be.

    John
     
  6. Joren_Wendschuh

    Joren_Wendschuh Member

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    there is an opticalisolator, with a resistor between the "hot" line, and itself, with the output of the opticalisolator, going to the control line on the Alternistor Triacs which is placed in between the hot line going to the load. the hot line going to the opticalisolator is before the Triac. The neutral line goes directly to the load.
    The Ultimate in simplicity. Hell, I built it myself :)
    hehe, if A drawing is needed, I will supply that.
    Any other information that could help you, whatever, just ask, I GREATLY apreciate your help, this should help keep my PAR-64's from blowing up with quite so much frequency :)
    Thanks!
     

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