Finally! The best of cadmium sulfide and silicon in one affordable photocontrol!

Dark To Light, a Division of Acuity Lighting, introduces the DE Series, filtered silicon photocontrols. These controls provide both reliability and accurate light sensing in one affordable electronic photocontrol. These new controls from DTL are sensitive to almost the same light wavelengths as the human eye. You get consistent, accurate turn off/on levels under variable weather conditions, even in extreme environments. So, you save costs.

The DE Series delivers two main benefits: 1) accurate light sensing and 2) excellent resistance to heat.

1. Accurate Light Sensing

Ordinary, unfiltered silicon sensor photocontrols cause inconsistent turn ON and turn OFF of luminaires. This happens because silicon sensors are especially sensitive to invisible infrared light. (See graph on back) This shows up as wandering of turn ON and turn OFF, depending on the sky color. On cloudy evenings, you will often get early switching; with brilliant red sunsets, you are likely to get late switching B sometimes too late.

DTL's new infrared-blocking, optical filter shifts the peak sensitivity of a silicon sensor to the visible light spectrum. Because infrared light is blocked by the filter, the control's peak spectral response is nearly that of the human eye. As a result, your lights will go on and off when people think that they should go on and off. Switching is consistent, reliable B pure performance in an affordable package.

2. Heat Resistance

In a well-designed electronic control, the drive circuit does not create significant heat. Therefore, there is no internally created drift of cadmium sulfide (CdS) or silicon sensors in electronic controls. Typically, it takes temperatures over 70EC to cause CdS controls to drift, at which point they exhibit a gradual but permanent change in on/off levels. In many of today's utility environments, this level of excess heat can be generated by fixtures themselves, sun loading or other causes. In mechanical controls, the circuits themselves often generate so much internal heat that, when combined with moderate external heat sources, drifting can be accelerated.

DTL's DE Series controls withstand temperatures in excess of 90EC. Even at elevated temperatures, you get more reliability plus accurate, consistent switching, night after night. Common model number is DE124-1.5-®.

With increased reliability and long-term, consistent light switching, you save maintenance costs. Also, energy usage becomes more predictable and measurable. Estimating for tariff purposes and contracts is more accurate.

The chart below shows three spectral response curves: human eye, unfiltered silicon sensor, and filtered silicon sensor. The human eye is most sensitive about 550nm (visible light range). Unfiltered silicon sensors reach their peak about 800nm, in the infrared range, well above the visible light range. Because unfiltered silicon photocontrols respond so strongly to infrared, control turn-ons/offs often seem to wander from day to day. On cloudy evenings, you may have early turn-ons (late turn-offs); on days with dramatic red sunsets, you may get late turn-ons (early turn-offs).

With an infrared blocking filter, the peak response of the silicon sensor is shifted back to about 575nm, very close to the peak response of the human eye. With filtered silicon sensors, DTL's DE Series controls see light the way people do. DE Series controls provide consistent, reliable switching.