20 thoughts on “What is an LDR? (Light Dependant Resistor) – Electronics Basics 26

  1. Hey! Explain Working priciple also on atomic level. //wht happnd int it when photons strike semiconductor? wht cause free its electron nd how resistivity drops???

  2. Great stuff man, thanks πŸ™‚
    I think if you put a parallel resistor with LDR, it will give it a desired range πŸ™‚ example 100 ohm, 1K…etc.

    Also to make ldr detect certain range of light like red, blue, green, use a colored transparent film on them, or use a marker of desired color, red, blue, green. and once done clean with some solution maybe polish nail remover, or alcohol, or acetone…etc. (trial)
    https://duckduckgo.com/?q=colored+transparent+film&iar=images&iax=images&ia=images

    There's an ok DMM (value for money) https://www.banggood.com/ANENG-AN8009-True-RMS-NCV-Digital-Multimeter-9999-Counts-Backlight-AC-DC-Current-Voltage-Tester-p-1216900.html

  3. Hi,

    You can use this in a laser spy audio microphone, right ? Or would a general smaller solar cell be a better choice ?

    Thanks.

  4. Are there LDRs that increase resistance when it’s surrounding get brighter? In other words: the same way there are PTC and NTC thermistors, are there positive and negative LDRs?

  5. Im confused. When light hits it, it has lower resistance and when its dark it has higher resistance. How will the street light or night life power on if the resistance is high? Pls help me understand thank you.

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