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--- eeng:topics:photocells:start [2022/10/20 18:38] – [Presentation] rolf
+++ eeng:topics:photocells:start [2023/11/22 01:07] (current) – [About LDR] rolf
@@ Line 1: / Line 1: @@
 ====== Photocells / Light Dependent Resistors (LDR) ======
+===== Lecture Slides =====
+  * {{ :eeng:topics:photocells:ldr_2022-09-22_v001_rb.pdf |}}
+===== About LDR =====
 | {{https://cdn.sparkfun.com//assets/parts/2/4/6/2/09088-02-L.jpg?200}} |
@@ Line 13: / Line 18: @@
   - {{https://resources.perkinelmer.com/corporate/cmsresources/images/dts_photocellsa9050.pdf|Photocells A 9050, A 9060}}.
-=== High Variability ===
-Do not trust the resistance-vs-lux curves too much. Adafruit states on its tutorial on Photocells for Arduino:
-"Each photocell sensor will act a little differently than the other, even if they are from the same batch. **The variations can be really large, 50% or higher!** For this reason, they shouldn't be used to try to determine precise light levels in lux or millicandela. Instead, you can expect to only be able to determine basic light changes." \\ (cited from **[[https://learn.adafruit.com/photocells?view=all|Arduino related tutorial on Photocells]], by Adafruit**)
+==== Large Variance among specimen of the same product series ====
-| {{https://cdn.sparkfun.com/assets/learn_tutorials/5/1/2/illuminance-vs-resistance.png?400&direct}} |
+The GL5528 datasheet from Sparkfun illustrates the broad performance variety between LDR of the same type:
-| Fig.: Typical performance variation of photocells of the same type (log-log-plot). \\ (Source: [[http://cdn.sparkfun.com/datasheets/Sensors/LightImaging/SEN-09088.pdf|GL 5528 Photodetector by SparkFun)]] |
-The [[http://cdn.sparkfun.com/datasheets/Sensors/LightImaging/SEN-09088.pdf|datasheet]] on GL5528 Photocell by **SparkFun** reflects these uncertainties.
+  * :!: https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/SEN-09088.pdf
-=== LUX ===
+==== LUX ====
 The light "intensity" illuminating the photocell is measured in **Lux**. This unit takes not just the physical light quantity but also the sensitivity of the human eye into account. It combines physics with physiology.
@@ Line 31: / Line 34: @@
-===== Lecture Presentation =====
-  * {{ :eeng:topics:photocells:ldr_2022-09-22_v001_rb.pdf |}}
+==== High Performance Variability ====
+Do not trust the resistance-vs-lux curves too much. Adafruit states on its tutorial on Photocells for Arduino:
+"Each photocell sensor will act a little differently than the other, even if they are from the same batch. **The variations can be really large, 50% or higher!** For this reason, they shouldn't be used to try to determine precise light levels in lux or millicandela. Instead, you can expect to only be able to determine basic light changes." \\ (cited from **[[https://learn.adafruit.com/photocells?view=all|Arduino related tutorial on Photocells]], by Adafruit**)
+| {{https://cdn.sparkfun.com/assets/learn_tutorials/5/1/2/illuminance-vs-resistance.png?400&direct}} |
+| Fig.: Typical performance variation of photocells of the same type (log-log-plot). \\ (Source: [[http://cdn.sparkfun.com/datasheets/Sensors/LightImaging/SEN-09088.pdf|GL 5528 Photodetector by SparkFun)]] |
+The [[http://cdn.sparkfun.com/datasheets/Sensors/LightImaging/SEN-09088.pdf|datasheet]] on GL5528 Photocell by **SparkFun** reflects these uncertainties.
 ===== LDR Voltage Divider Experiment with Arduino =====