What are Pinspots?
Pinspots are low-voltage high intensity beamlights. The lamp used in a pinspot is usually a PAR36 lamp known as a ‘4515’ (originally designed for airport use, as aircraft landing lights). The lamp requires 6 Volts and 30 Watts.
To give the lamp that voltage, the case of the Pinspot contains a small transformer, that reduces the voltage from 120 Volts (US) or 230 Volts (UK/Europe) to the required 6 Volts.
They can be used for very tight specials (e.g. a glow of light on a prop, or a tight special on an actors’ face) or for lighting a mirrorball.
I was told I can’t use them on a dimmer. Why not?
Most stage lighting dimmers are designed for resistive loads. That is, they’re designed to have filament lamps connected to them, which provide a resistance to the electrical current, which causes the filament to glow white hot, and produce light.
A pinspot, as it contains a transformer, presents an inductive load to the dimmer.
US power runs at a frequency of 60Hz, that is, there are 60 complete cycles of alternating current electricity every second.
UK power runs at 50Hz.
The upshot of this is that in the US, the dimmer switches off and on 120 times a second, once in the positive cycle and once in the negative cycle. This rapid switching on and off generates heat in the transformer, which will eventually cause it to fail.
The dimmer can also be damaged as the inductive load passes current back to the dimmer which can damage components.
But I’ve been using pinspots in dimmers for years!
Some dimmers (check with the manufacturer) CAN cope with inductive loads, including transformer-fed instruments such as pinspots, and fluorescent lights.
What should I do if I want to use a pinspot in my show?
You can ‘fool’ a dimmer into thinking it has a resistive load by using a load lamp, also known as a dummy load. This is a low wattage (100 – 200 Watt) lamp which is connected into the same dimmer as the pinspots to ‘load up’ the dimmer.
You can also check to see whether the type of dimmer you’re using is happy with inductive loads. If so, go ahead and use as many pinspots as you like!
Does this apply to other transformer-fed lighting such as low voltage birdies?
Yes – the above applies to all such equipment.