Lightdependent Resistor (LDR) — Model 2761657 The cadmium sulfide (CdS) or light dependent resistor (LDR) whose resistance is inversly dependent on the amount of ambient light intensity is known by many names including the photo resistor photoresistor photoconductor photoconductive cell or simply the photocell. Its resistance decreases from millions of ohms in darkness to a few hundred ohms in bright light. Each application requires an appropriate circuit and physical setup and some calibration may be required for the exact lighting scenario encountered. Able to detect large or small fluctuations in light levels it can distinguish between one or two light bulbs direct sunlight total darkness or anything in between. A typical structure for a photoresistor uses an active semiconductor layer that is deposited on an insulating substrate. The semiconductor is normally lightly doped to enable it to have the required level of conductivity. Contacts are then placed either side of the exposed area. The photoresistor CdS or LDR finds many uses as a low cost photo sensitive element and was used for many years in photographic light meters as well as in other applications such as smoke flame and burglar detectors card readers and lighting controls for street lamps. Features: Quick Response Reliable Performance Epoxy Package Good Characteristic of Spectrum Applications: Photoswitch Photoelectric Control Auto Flash for Camera Electronic Toys Industrial Control Specs: Coating: Resin (All) Voltage between Terminals @ 25° C: 100 VDC Power Dissipation @ 25° C: 70 mW Ambient Temperature Range (C): 30 +80 Spectral Peak: 540 nm typical Cell Resistance 0 Lx: 5 MOhm minimum Cell Resistance 10 Lx: Min 20 kOhms 60 kOhms Gamma 100/10: 0.75 typical Prehistoric Error (Change PE) @ 1 Lx: +0.10 for 30 sec typical Prehistoric Error (Change PE) @ 1 Lx: +0.15 for 120 sec typical Color Temperature Error (Change CE @ 10 Lx): 0.15 typical Response Time @ 10 Lx: 40 ms Rise typical Response Time @ 10 Lx: 30 ms Decay typical Specifications are typical; individual units might vary. TYPE ILLUMINATION @ RESISTANCE ILLUMINATION @ RESISTANCE P7227R: ......... 1 Lux .....@.. 13 kOhms ..... 100 Lux ....@... 900 kOhms P7225R: ......... 1 Lux .....@.. 15 kOhms ..... 100 Lux ....@... 1.1 kOhms P1201: ........... 1 Lux .....@. 120 kOhms ..... 100 Lux ....@..... 7 kOhms P201D7R: ........ 1 Lux .....@. 130 kOhms ..... 100 Lux ....@..... 8 kOhms P201D5R: ........ 1 Lux .....@. 160 kOhms ..... 100 Lux ....@..... 9 kOhms CELL RESISTANCE POWER VOLT.BETWEEN 10 LX RESPONSE TIME TYPE DISSIPATION TERMINALS 0 LX MIN~MAX RISE DECAY P7227R: .. 150 mW ... 200 VDC . 0.5 MOhms . 2.5~7.5 kOhms ... 50 ms . 40 ms P7225R: ... 70 mW ... 100 VDC . 0.5 MOhms . 5.3~15 kOhms ... 50 ms . 40 ms P1201: ..... 70 mW ... 100 VDC ... 5 MOhms .. 20~60 kOhms ... 40 ms . 30 ms P201D7R: . 100 mW ... 200 VDC .. 20 MOhms .. 23~67 kOhms ... 50 ms . 20 ms P201D5R: .. 50 mW ... 100 VDC .. 20 MOhms .. 48~140 kOhms ... 50 ms . 20 ms
