Moving Lights

[James169]

Hi guys,

 

 

basically I'm trying to build a very basic equivalent of a moving light for a project at my Sixth form and was wondering if anybody could give me some advice

 

 

 

it wouldnt need to be DMX, but maybe have a usb as it wouldn't be used for anything other than a demo to show it works

[Brian]

Moving lights normally use stepper motors to move things. With the appropriate drive train and position feedback they have the advantage of swift movement and high torque. They are also quite expensive to buy, the drive train can be difficult to mock up and their control isn't always cheap.

 

How about using some RC model servos? If you look at the Milford Instruments website they do an 8-channel DMX to Servo controller board (under £40) and servos can be had for under £5 each from ebay.

[phenry]

Moving head, or moving mirror? How big is this going to be? Do you already have any parts to salvage?

 

I would use an Arduino with a stepper motor shield, and add a max485 DMX chip for DMX control, but that is just because that is what I have the most access to. If you are doing a moving mirror fixture, I like the idea of the DMX servo controller.

[timsabre]

What Brian said - and servos come in different "torque" (power) ratings, depending on how big your light source is, you might need quite beefy ones which are a lot more than £5 each.

 

I've designed the drive system inside quite a few moving lights and the stepper motor drive is quite complicated to do well, you need to do "microstepping" or everything will be very jerky.

[James169]

I'd be looking to use a moving mirror as I believe it's cheaper (I may well be wrong but I'm new to moving lights) and hopefully it will only be a small light

[Brian]

Something like this?

 

 

That's about as simple as it gets as it uses just two motors (steppers).

[DrummerJonny]

100% go for a Mirror. Otherwise you'll have the additional worry of sending your cabling through 2 separate pivot points to power the lamp / any other gubbins you may want.

[ceecrb1]

This could be done very simply and cheaply... in a manner that already has many tutorials online that can guide you through it.

 

50W halogen lamp,

http://www.efficientlight.co.uk/Images/Light/Light-Bulbs/gu10_halogen.jpg?format=jpg&maxWidth=600&maxHeight=450

 

Plus an arduino.

There are even arduino starter kits with servos and breadboards etc in the box ready to go.

http://en.wikipedia.org/wiki/Arduino

 

plus camera servo mount:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=31562

These servos MAY be a little slow and weak.. but metal geared high speed servos are really cheap these days.. EG I replace mine in my petrol rc aerobatic plane yearly as they get sloppy from the engine vibrations.. mine will move 12kg at 1inch from the centre hinge point.. and they cost 27 dollars each or something.

 

+ mirror.

 

+ Tutorial:

[Don Allen]

Do you have a list of design features ?

 

Moving lights need initialisation and positioning information, something built into servo motors.

 

If you can keep it simple like accepting the pan and tilt range of an off the shelf servo motor, it will be an easier design.

 

Do you want gobos ? If not then look for an RGB torch to use as the light source as that will demonstrate positioning and colour changing ability. You only need the front lens section of the torch so it will look like a moving head. (well sort of).

[Superpants]

Sounds like a good project. I’d concur with the other comments to make a moving mirror unit- the mass you need to move will be much smaller, and hence the servos/ motors you need can be smaller and cheaper, and/or the mirror can respond quicker.

 

Old laser printers and photocopiers and to a lesser extent inkjet printers contain loads of small parts such as bearings and gears, optics and importantly stepper motors- you ought to be able find an old one you can scrap for parts to help you along should you be pushed for cash.

 

Have you thought about your light source- You might be able to find an old slide projector lurking in the back of a store cupboard that could also be cannibalised to give you the necessary optics- particularly useful if you need to project a gobo.

 

 

[kitlane]

Try and get hold of the book 'Automated Lighting' by Richard Cadena. It is a good introduction to most of the different aspects of what goes into building a moving light.

[James169]

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Try and get hold of the book 'Automated Lighting' by Richard Cadena. It is a good introduction to most of the different aspects of what goes into building a moving light.

 

Funnily enough I got this book a day or two before posting on here, haven't had a chance to have a proper look through it yet

[James169]

hi everyone, thanks for all the suggestions, I've started putting the light together now, its not going to be on DMX, just has an on/off switch and runs on batteries. I should get it finished this week, thanks again

 

 

 

James