Light dependent resistors, also called photoresistors, are simply resistors whose resistance changes based on how much light is falling on them.
All of my LDRs go from close to zero ohms of resistance under very bright light, to over 200 million ohms (200MΩ, which is my LCR meter’s limit) when completely dark/covered.
Affiliate link ad. These look to be the same type of LDRs that I got from a couple of kits that I have. such as the following kit.
The 555 timer wired in astable mode, charges a capacitor from the supply through resistance while the output is high. Once the capacitor reaches 2/3 supply voltage, the output goes low and the capacitor discharges through the discharge pin to ground until it drops to 1/3 supply voltage. Output goes back high and the capacitor starts charging again.
Having a light dependent resistor between the capacitor and discharge pin means that light intensity will be the primary resistance factor that sets the timing involved for any given value of capacitance that is being used.
- Brief passive buzzer controlled by 555 timer astable multivibrator set by light dependent resistor LDR circuit
- Quick zener diode improved by NPN BJT emitter follower circuit – 2N3904 bipolar junction transistor
- Brief comparator circuit using single supply op amp and voltage dividers – LM358
- Brief look at discovered problems with using LM358 op amp as a single supply comparator
- Brief inverting op amp comparator circuit – LM358
- Brief active buzzer component introduction
- Brief zener diode component voltage reference and shunt regulator basics
- Brief PNP BJT emitter follower common collector – 2N3906 bipolar junction transistor
- Brief NPN BJT emitter follower set by trimpot using 2N3904 bipolar junction transistor
- Brief PNP BJT current source set by trimpot circuit – 2N3906 bipolar junction transistor
Some nice low power boost converters above that I enjoyed using in a couple videos.
Don’t have this buck converter, but it looks nice.
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- Information on this site is not guaranteed to be accurate. Always consult the manufacturer info/datasheet of parts you use. Research the proper safety precautions for everything you do.