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walk/no walk flashing sign

Discussion in 'Special Effects' started by chslighttech, Oct 26, 2005.

  1. chslighttech

    chslighttech Member

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    Heres the deal. I have this walk no walk street sign. Its one of the ones that are put up on streetlight poles with the red hand and the blue person walking which usually blinks whichever one it is on. I found this sign and both of the lights were wired into one cable and when you plug that in they both go one. I am going to rewire them so that each light is one its own switch. But the problem is that i need it so that when i flip the switch on whichever light i turned on will blink. I need to find something that will cut the current on and off so that it will blink but I dont know what i need to look for. Any help is appreciated. Thanks
     
  2. CHScrew

    CHScrew Active Member

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    I did this same thing. I went to "Big Lots" department store and bought some Christmas lights that were on sale. They have this little 2X2X2 box that had buttons on it so the lights blinked in different patterns. I just wired the box into the cable. It worked fine.

    Hope this helps.

    ~Ray
     
  3. AVGuyAndy

    AVGuyAndy Active Member

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    How many amps do the lights pull, and I assume 120v?
     
  4. chslighttech

    chslighttech Member

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    120 volts and 100 watt bulbs so doing the math it would be .83 for each individual light and theres only two.
     
  5. AVGuyAndy

    AVGuyAndy Active Member

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    Yeah, I would definately try to find those christmas lights with the control box.
     
  6. sound_nerd

    sound_nerd Active Member

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    If you have a simple "dj" chase controller sitting around you can program that to the speed you want.
     
  7. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    Do you have enough channels on your dimmer to run these 2 lights? If so, just hook them up and use the flash buttons to control them
     
  8. chslighttech

    chslighttech Member

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    I was thinking about doing that. We only have 24 and were doing damn yankees and were gonna need all of them so I kinda wanted to have them all by themselves. ill have to go look for those christmas lights cause that seems like the best option for me at the moment. Thanks for the help everybody.
     
  9. CHScrew

    CHScrew Active Member

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    I think I found a set that has the control box. It isn't the brand that I used but I think they will work. They have " an 8 function memory control box you can set the lights to twinkle, chase, move, steady on, sequence and other exciting effects." They're the first ones on the page.

    ~Hope this helps.

    http://www.gardensite.org.uk/worldofchristmas/lights.php
     
  10. jbeutt

    jbeutt Active Member

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    Just a thought. Cars use flashers to control the turn signals and emergency lights in the car. Here's a link to the parts:
    http://www.partsamerica.com/ProductList.aspx?PartType=121&PTSet=A&SearchFor=Flashers

    I'm sure there's some way to utilize that to get your controlled flashing.
    For instance, wire it with a 3 way switch. pos1 is off, pos2 is flashing, pos3 is solid.
    Just about the cheapest and easiest way you could do it i think.
     
  11. drumbum

    drumbum Member

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    The one thing you guys are not mentioning how it is actually done . . . street lights and all that use a PLC . . . programable logic controler to control when they turn on, or blink . . .same thing with your car . . . commonly refered to as the computer in your car. Thing is they work great . . . and one thing that i think everyone is learning on this forum is that the thing you want is always to expensive.

    SO with that being said, you can buy pieces for what you need at radio shack to make one blink. there are a few ways you can go about it, including a relay and timer chip . . .different sized resistors for different times. Give it a shot, see what you get.
     
  12. jbeutt

    jbeutt Active Member

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    chslighttech - how long is the run? That'll probably make a difference to how much effort you want to put into this thing.
     
  13. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    The flasher unit is simply a capacitor and a relay. The cap charges and then discharges turning the relay on and off. The relay in turn turns the lamps on and off.

    Problem is that the 12V car lights are probably not going to be bright enough for your application. You could use a car flasher unit to trigger an AC relay which would then turn on your 120V lamps.

    This is fairly easy to do, so long as you are competent in wiring up an AC realy in a safe manner and the school would actually let you do so. This is the main reason that I didn't mention it before. That and the fact that running it from your desk would have been the simplest solution.

    The car flasher doesn't require a car battery to power it either. Any 12 volt power supply will work to operate the coil. The voltage that you run through the actual contacts for the flasher relay would need to be matched to the operating voltage for the coil on the AC relay.

    In fact, you don't actually need the car flasher if you can work out the value of the capacitor that would be required to generate the pulse to trigger the coil in the AC relay.

    A rental house may even have such a controller that they may have had made for a show. Probably not, but it is a chance.
     
  14. jbeutt

    jbeutt Active Member

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    I wasnt suggesting using car lights, but to be honest, they probably would be bright enough.

    He wants the lights to flash. I'm fairly sure a relay won't do this, but please correct me if i'm wrong. the flasher in a car is not a relay, it's a thermal flasher.
     
  15. jbeutt

    jbeutt Active Member

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    oh man, i don't know why i didn't think of this before, but you could also try using the flashing unit in stobes. Many electronics places will probably sell just the control/flaher unit.
     
  16. JahJahwarrior

    JahJahwarrior Active Member

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    Or, if you have a strobe, just rewire it so instead of the lamp in the strobe, it sends it's signal to the lamp in your light. If you don't need both lights to flash at the same time, you could wire a 3 way switch in, between the street crossing sign and your strobe--this way middle is off, and depending on which side you flip to, a certain light will blink.

    You can even make it non destructive to your strobe.....wire it all up safely and stick it in a large rubbermaid box or something, rather than say, mounting it in a chassis.
     
  17. kingfisher1

    kingfisher1 Active Member

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    pesonally running from the desk would be the simplest idea, maybe not as fun as some of the others. any limitations as to why it can be done from the board?
     
  18. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    The older style flasher units are bimetal (thermal) units. However, newer ones are either relay driven or solid state. The relay driven ones use a capacitor to trigger the coil.

    When the capacitor discharges its load, the relay is triggered, turning on the lamp. Once the capacitor has finished discharging, it will then re-charge. Whilst it is recharging it can no longer keep the relay coil energized, thus the relay breaks contact and the lamp turns off. This cycle continues until the circuit is broken. (i.e. you trun off the indicator switch).

    I think I have a flasher unit in my workshop somewhere that is inside a clear plastic housing. You can clearly see the capacitor and the relay. I also think there may be some resistors in there to drop the voltage to something more suitable for the relay coil. If I remember, I'll look for it and take some pics.

    I am pretty sure that the older units actually draw more power in heating up, where as the newer ones do not need as much current.

    Remember that relays are mainly used to control a device that requires a large amount of current or voltage.

    For example, when you fit a set of spot lights to your car, you do so using a relay. If you simply ran them off the same power supply as your head lights, they would be very dim and eventually burn out the cable supplying the power. What you do, is use the power from the headlight circuit (or from the switch controlling them to power up the coil in the relay. You then run an appropriate sized cable from the battery or main feed for the fuse box to connect to one of the terminals on the relay (with an inline fuse). The other terminal on the relay is connected to the spot lights and the remaining terminal on the spot light is grounded.

    The other use of a relay is to use a low voltage DC or AC current to switch on a high voltage AC load. I used this system to power up the motor in my bore. The sprinkler system runs off of 24V AC to operate the solenoid valves and so I used the 24V feed to trigger a 240V relay, which in turn powered up the electric motor. Couldn't have powered it up just form using the 24V feed!

    This application is similar. Use a low voltage trigger to power up a high voltage device. I actually built such a system to hire out to bands that cannot afford to hire out a lighting system and operator. I use a DPST relay to control 2x 240V outlets (into these they plug 4 coloured lights (e.g. 2x Red and 2x blue) and place them either side of the stage). When the unit is powered up, the 2 blue lights come one. When the relay is triggered, the blue lights turn off and the red lights turn on. It is a simple and cost effective way of changing their wash.

    The triggering is done using low voltage DC and is done so by a standard guitar foot switch and connected to the switching unit by a TS to TS lead. By using low voltage DC, if anyone accidentally unplugs the lead or damages it, there is no risk of shock to them. All the 240V is contained within the sealed box.

    This system works very well and allows one of the band members to change their stage wash by simply pressing a button.

    However, if you think that a 12V DC lamp would be bright enough, all you need to do is find a power supply that is adequate to do your task and wire that up to two switches. If you use SPST momentary action switch you could manually flash the lights at any speed you like.
     
  19. chslighttech

    chslighttech Member

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    Thaks for all the help the show is only showing like 6 days but I will keep the sign to hang onm the wall on the staircase leading up to the booth for a joke and use it there. So its not gonna get thrown away after im done with it.
     
  20. jbeutt

    jbeutt Active Member

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    Well now you know all about relays. 8O Thanks. I know what the function of the relay is, I just thought cars still used the thermal flasher. Good to know they don't. I guess doing it with a relay you'd be able to customize the timing with more ease and save a little power.

    Might as well do the sign now anyway, with all this effort gone into figuring it out. :) You can pass it on to someone in dire need for a street light prop.
     

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