Fixed Slide Projector With Low Energy Consumption

The luminous image projected by a slide projector is a nice and easy way of adding character to a room. Drawbacks of the slide projector as a fixed lighting element however are that its power consumption is relatively high and that the internal fan produces quite some noise.

In this instructable a slide projector with an electrical power consumption of 195 W is being rebuild to function at 18 W (corresponding to 91% energy saving). As a result, the light yield of the bulb has reduced by 95%. However, since the luminous power in the original state is far above what is required for atmospheric lighting, the new state of the slide projector is perfectly suited for use in the evening, when it's getting dark. The modification is completely reversible, it will not affect the slide projector's state (see also step 1 on safety). All pictures in this instructable show the case of the modified projector.

The diapositives used in this instructable show paintings by the Dutch painter Vincent van Gogh (1853–1890): 'Landscape at Twilight' (1890), 'Farmhouse with Two Figures' (1890) and 'The Langlois Bridge' (1888). 

Core of the rebuild is to replace the 150 W (24 V, 4500 lumen) halogen bulb by a 14 W (12 V, 205 lumen) halogen bulb. Initially the plan was to use a powerful LED instead, but this didn't work out well. The highly concentrated, powerful and uniform light that a halogen lamp provides is key for creating a nice lighting effect with a slide projector.

Another major improvement is that the cooling fan that was required for the 150 W lamp could be replaced by a much smaller and thus more silent fan. This modification makes the slide-projector particularly suitable for use in a living room.

Note that the slide projector used is a conventional device based on a light bulb with an incandescent filament, placed in the focus point of a lens and a reflector. It might work with a modern LCD-based projector as well, but it's not sure that this can be done in a reversible manner. Moreover, the advantage of a slide projector is that the mechanism to hold the diapositive is in place already.

Safety warning: both in the original setup as in the modified state the fan is required for cooling the lamp. Cooling will remain absolutely required, also in the new layout with the less powerful bulb. Omitting the fan will most probably result in a fire. For this reason the device should never be run unattended and supervision of a knowledgeable adult is required. See also step 1.

In the last steps of this instructable two previous openproducts lighting projects have been displayed: the Giant Ceiling Light (step 7) and the Wooden Light-rail (step 8). Step 9 documents the innovative aspects of the Low-power Slide Projector and step 10 addresses licensing issues.

Step 1: Safety and Risk of Fire

Both in the original setup as in the modified state the fan is required for cooling the lamp. Cooling will remain absolutely required, also in the new layout with the less powerful bulb. Omitting the fan will most probably result in a fire. The new layout has no intrinsic safety measures like temperature sensors or fuses, which might be present in the original state. For this reason the device should never be run unattended and supervision of a knowledgeable adult is required.  

For powering the cooling fan preferably use the same transformer to make sure that the fan is automatically on when the light is on.

If a temperature sensor is in place (usually close to the lamp) it can be integrated in the circuit powering the lamp. This has not been shown in this instructable. Note that this measure makes the setup safer, but continuous supervision remains required.

Step 2: List of Material

All electrical parts in the original device will not be used in the new setup: the 14 W halogen lamp and the cooling fan will be powered by a separate transformer.

If it is not important to keep the slide projector intact it is also possible to take out the lens and mirror of the projector. This will result in a smaller installation dimensions. From the slide projector only the lenses, reflector and the holder of the diapositives are being used.

Material required:

 - a slide projector and slides
 - 12 V 14 W halogen bulb (or similar*) including a socket
 - a cooling fan: low power, low noise (and low voltage)
 - a transformer to power the halogen bulb (and the cooling fan)

In this instructable a modified halogen desk lamp was used as a lighting source.

* The modification works fine as well with a 5W halogen bulb (9 W including transformer and fan, resulting in 95% energy saving). Cooling remains required. It is strongly discouraged to use bulbs with higher power rating because of the risk of fire, see also step 1.

Step 3: The Original Setup

Obviously, the luminous image using the original lamp (150 W) results in a very bright picture, albeit at a high electricity consumption rate and with a disturbing noise from the cooling fan.

An alternative approach is to use a dimmer-switch for reducing the energy consumption of the slide projector. This however was not successful: power consumption was reduced to 50 W at almost no light emitted.  

Remove the lamp from the projector to start rebuilding the projector (see next step).

Step 4: Installing the New Bulb

Create a construction that allows to place the incandescent filament of the lower-rated halogen bulb in the focus point of the lens and the reflector in the projector. This spot can be found easily as it is exactly where the high-power bulb was located. Also the sharpness of the luminous image on the wall is an indicator for the correctness of the bulb placement.

Attach the transformer to power the bulb. Do not yet switch on the light as the cooling fan first needs to be installed properly. See the next step.

Step 5: Installing the Cooling Fan

Install the cooling fan and make sure that there is no leakage, i.e. all air sucked away by the fan should be led along the bulb in order to reach a maximum cooling effect. For powering the fan preferably use the same transformer to make sure that the fan is automatically on when the light is on. In this example a separate transformer was used, but this thus introduces an additional safety risk.

Step 6: Hide the Projector

A nice place to hide the projector is on a book shelf opposite the projected wall. The slide projector can be hidden between books, and a fake sheet of book spines covers it really well.

Step 7: Other Lighting Objects by Openproducts: UFO Lamp

Previously, openproducts has released a Giant Ceiling Light with Multiple Functionality a.k.a. the UFO. The instructable has been licenced under CC-BY and has been published on September 13th 2012: https://www.instructables.com/id/Giant-ceiling-light-with-multiple-functionality-a.

Step 8: Other Lighting Objects by Openproducts: Wooden Light-rail

Early 2013, openproducts has released a Double Function Rail for combined hanging of paintings and indirect lighting. The instructable has been licenced under CC-BY and has been published on January 7th 2013: https://www.instructables.com/id/Double-function-rail-hang-paintings-and-indirect-.

Step 9: Innovative Aspects

The concept described in this instructable has innovative aspects. These are:

 1. Replacing a high-power lamp in a slide projector by a low power lamp leaves its functionality intact (albeit at lower light yield) and reduces electricity consumption significantly;

 2. Replacing the noisy built-in cooling fan by an external silent fan reduces the noise and makes the projector suitable for continuous use in the evening;

Important to note however is that the original safety measures such as temperature sensor and fuse are being bypassed, which makes cooling an important aspect. The modified projector requires constant supervision of a knowledgeable adult. See also Step 1 on safety.

The next step elaborates on the license type chosen for this instructable.

Step 10: License

This instructable is made available through a Creative Commons Attribution Non-commercial Share Alike (by-nc-sa) license. The innovative part of the concept has been described in Step 9.

Republishing this instructable in a non-commercial venue under that same license is allowed, provided it is being attributed properly (cite the name openproducts, link to www.openproducts.org, https://www.instructables.com/member/openproducts, or the original Instructable.

For other arrangements send a Private Message through the instructables member page (https://www.instructables.com/member/openproducts). Openproducts is open to agreements on innovative business models for commercializing the low-power slide projector.

If this design infringes any rights then refer to Article 28 in the Terms of Service (https://www.instructables.com/tos.html).