Making Bespoke Dimmer Switch Unit to Use With Halogen Lights For Photography Studio Lighting
Thinking Out of the Box
Lighting Solutions for Homemade Studio Lights, Photography, Garden BBQs and Parties
This article is about Rigging Dimmer Switches to Work with Halogen Lights as a portable unit to use in film studios, in poorly light areas and at night. specifically designed for filming and photography; although once made these units can have a multitude of domestic uses around the home and garden e.g. excellent for BBQ lighting.
Natural light (ideal for filming) is around 5,600K. Tungsten builds, although they may look white to the human eye in fact produces a yellow light in filming; whereas halogen produces a more natural warm white light.
However, proper studio lights are not cheap to buy. Therefore, after some research we decided to use commercial 500w building-site halogen lights, which at around £35 each is significantly cheaper than comparable professional studio lighting units than can cost £100s.
My son on recently passing his degree in media broadcasting is keen to build-up a freelance business in filming and photography. Working with a mate they've got off to a good start with a few filming projects under their belt, but until they build up their business they are working on a shoestring budget; and ancillary equipment, such as proper studio lighting (vital in such a business) can cost thousands of pounds sterling, which is obviously is well beyond their reach at this time.
Hence their desire to design and build their own homemade studio lights from household objects, and in this context their decision to buy building-site halogen lights, was a natural choice for a basic solution.
Mains Halogen Lights
Building Site Halogen Light Units
Building-site halogen lights are basically the same as the exterior halogen security lights which you may have on the outside wall of your home and use the same R7s/RX7s bulb; and like the halogen home security lights are water resistant but being designed for building sites these light units are also portable and very durable; portable as being either floor standing or on tripods.
However, to use these halogen lights to their full effect for filming and photography you need to be able to control their output e.g. to dim the lights as and when appropriate. So the task I was charged with was to research and find suitable dimmers for halogen lights of this type and rig up a control box from where the lighting could be remotely controlled. This lens provides a summary of my research and the basics in constructing the lighting control box. The total cost of the three 500w building site halogen lights they wanted and the additional material needed to complete this project was just 160 (significantly cheaper than comparable studio lighting).
And as a bonus these lights, and the home made bespoke dimmer unit described below, will also be ideal for all those other occasions where bright lighting would be beneficial e.g. lighting up those BBQs and garden parties thrown together at the last minute on a hot summer's day, giving your party guests a much brighter time!
1500w Single Pole Dimmer
Ideal for Halogen Lights
Halogen lights as discussed in this how-to article are very bright and to be able to control that brightness, and dim it, with a good and suitable dimmer switch gives you control over the desired brightness e.g. dimming the lights during a garden party in the evening and then bringing the lights up to full strength during speeches, announcements and when the buffet is served.
Choosing the Right Dimmer Switches for Mains Halogen Lights
De-Rate the Lights to Match the Load Output of the Dimmer
The building site halogen lights chosen for this project was a twin 500w light unit on a sturdy tripod with one plug, each light being 500w, total output 1000w; and a freestanding floor halogen light unit of 500w. The first thing for me to establish was what type of dimmer switch would be compatible and the minimum output load capacity (wattage rating) would be required for safe operation for these halogen lights, at 500w using R7s/RX7s bulbs.
The Light Source being used in this project is described as 'Resistive', lamps with a filament, which emits heat and visible light; typically standard GLS incandescent and mains halogen lamps therefore dimmer switches designed to control 'Resistive' circuits would be required. In other words (laypersons terms) ordinary dimmer switches used for standard mains lights in the home, 240v in Europe (120V in America).
However the dimmer switch has to support the capacity of the light, taking into account that when using a dimmer halogen lights have to be de-rated by 25%. In laypersons terms, with halogen lights the dimmer switch requires a 25% spare capacity e.g. a 400w halogen light would require a 500w dimmer switch. The reasons for using a dimmer with spare capacity is that halogen lights produce a lot of heat and if the dimmer is running at full capacity it will also generate a lot of heat and burnout quickly; likewise when a halogen bulb blows it generates a brief surge of electricity which can also blow the dimmer if it's running at full capacity.
Heat Generated by Dimmer Switches
Dissipating Excess Heat Safely
All dimmer switches generate their own heat and need to dissipate one watt (heat) for each 100w of controlled load and because of this if two or three dimmers are next to each other the maximum load each switch can safely handle drops considerably and so they have to be de-rated for safe use, by 20% for two switches and 40% for three e.g. three dimmer switches next to each other each rated for a maximum load of 500w would only be able to safely handle 300w each. Housing of the dimmer switches is another important consideration; the back boxes needs to be metal rather than plastic to absorb some of the heat which can then be dissipated either through the wall or from ventilation e.g. air gaps rather than insulation behind the back box.
Some of the more expensive dimmer switches have an inbuilt inhibitor which steps down the power (wattage) of the halogen light to the maximum safety level permitted by that dimmer e.g. a 500w halogen light controlled by a 500w dimmer of this type would only ever run at 400w maximum. A 500w halogen light de-rated would require a dimmer switch rated for at least 625w load to run safely but above 600w the next dimmer switches available are 1000w.
Therefore, for this project, the simple solution was to re-wire the twin 500w lights so that each had its own separate plug (rather than just the one plug for both lights) and to buy three 1000w dimmer switches so that each of the three halogen lights; the twin lights on the tripod and the floor light have their own dimmer switch with sufficient spare capacity to allow for the de-rating of the halogen lights and the dimmers themselves.
Making a Bespoke Lighting Control Box
Using Basic and Inexpensive Materials
The construction of the control box to house the three dimmer switches and three power socket outlets is simple and inexpensive to make using just basic materials; in this case:
- A piece of floorboard 8" (200mm) wide by 1" (25mm) thick, and
- A piece of 12mm plywood for the base.
- The timber was cut to size to make a box approximately 12" (300mm) long, 8" (200mm) wide and 5" (125mm) high.
- The four sides and the top made (using the floorboard as timber) is glued and screwed together
- The base made from the plywood is cut to size but only screwed in place (not glued) with four screws; for easy access.
- Three square holes, slightly larger than the metal back boxes for the switches are cut out of the front of the wooden box at regular intervals; with at least 12mm gap between each hole. These openings will house the electrical power sockets.
- Another three square holes (the same size as the first three holes) are then cut out from the top of the box. These openings will be for the three dimmer switches.
- Cut a hole into the side of the box to house a suitable male power-in socket into which the mains power supply can be plugged.
- Firmly screw and glue a piece of wood inside the wooden box behind the square holes previously cut-out to house the dimmers; and likewise another piece of wood inside the box behind the square holes cut out to house the three electrical power sockets. These two pieces of wood will then provide a firm back onto which the metal back boxes can be securely screwed.
- As adequate ventilation is vital to dissipating heat generated by the dimmer switches knock all four holes out of the back of each metal back box to help with air flow,
- screw each metal back box firmly into the square cut-outs, and drill a hole through each of the four knockout holes and through the wood behind.
- Also drill a series of 12mm holes in the back of the wooden control box or make a cut-out hole in the back to house a vent; to provide sufficient ventilation for the heat generated by the dimmer switches.
The Finishing Touches
Sand down the wooden box and finish it to taste. For example, wood stain and or wax it, or paint it any colour you wish and leave to dry. In our case we used a wood stain followed by bees wax.
Fitting and Wiring the Dimmer Switches
And Associated Power Sockets
Finally, wire in and fix the three dimmer switches, three power sockets and power inlet socket in accordance with the electrical wiring regulations appropriate for your country; this should be done professionally, if in any doubt seek professional help.
Basically, the power coming in needs to be split three ways e.g. one for each switch and its associated power socket, this should be done using a 30 Amp junction box or 30 Amp Terminal blocks (chocolate blocks). 30 Amp because the screw and screw holes are large enough and strong enough to safely (securely) accommodate the four wires for each of the live, neutral and earth.
For each dimmer switch and power socket:-
- 'Live' goes from the junction box (terminal block) to the L1 (Live of the dimmer switch).
- A wire then goes from the Common terminal on the dimmer switch to the Live (L) on the power socket.
- And the Neutral (N) on the power socket returns to the Neutral in the junction box (terminal block) to complete the circuit.
- The earth (E) from the junction box (terminal block) should be appropriately connected to all sockets and switches.
If in any doubt consult a professionally qualified electrician; if you don't know what you are doing then apart from gas there is little that is more dangerous to play with in the home than electricity e.g. far better to be safe than sorry.
Ideal Lighting Solutions for BBQs and Garden Parties
How often have you taken photos indoors and wished you had more natural light to get a better photo or held a BBQ wishing you had better outdoor lighting.
Variations on a theme, you could build a control box for two dimmer switches and buy two 400w building-site halogen lamps, either as a twin lights on a tripod or as separate floor lights for use at your BBQs/Garden parties, ideal for outdoor use as they are weatherproof. But be mindful that you buy the correct voltage, some units in the UK are only 120v specifically for running from generators so you need to be sure you buy the building site lighting units rated at 240v.
Do remember that the wooden control box isn't weather proof and would need to be housed under suitable shelter during wet conditions. Also, be mindful of where you lay cables, you don't want people tripping over trailing wires. Then you can hold your outdoor parties and entertain your guests dimming the lights to match the mood and brighten them up to full power at the end when you're clearing up and or during any special moment during the evening such as speeches and cutting birthday/anniversary cakes etc., be safe and have fun.
Producing Natural Light Artificially
Daylight is White Light
Artificial light never matches natural daylight, white light being made from a blend of the seven colours of the rainbow. Most artificial light sources although they may look white to the naked eye usually produce a yellow light which wreaks havoc with photography and filming; but some artificial light sources such as fluorescent tubes can come close to matching daylight in colour. Do you know what other artificial light source produces a more pure white light rather than yellow light?
Which of these two light sources produces white light?
Filming and Photography
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This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2012 Arthur Russ