GL4516 LDR

The GL4516 LDR is a light-dependent resistor with a max voltage of 150VDC and a maximum power dissipation of 50mW, for hobbyists building lighting projects.

LDRs (light-dependent resistors), also referred to as photoresistors, are light-sensitive devices used to detect light levels, e.g. in automatic security lights, to indicate the presence or lack of light, or to measure the intensity of light. Their resistance decreases as the light intensity increases. In the dark and at low light levels the resistance is very high and little current can flow. When the sensor is exposed to light, the resistance drops dramatically, depending on the light intensity. LDRs have a sensitivity that varies with the wavelength of the light applied, and are non-linear devices.

LDRs are very sensitive to changes in light intensity, so they can detect even small changes in the amount of light that is present. That is useful in automatic lighting systems and photography equipment. They are also durable and operate reliably over long periods of time, so they can be used where continuous operation is required, such as in outdoor lighting systems or security systems.

Which resistor to use with an LDR?

The LDR value and resistor value are chosen to balance current draw, ADC input impedance and light response. The easy answer is to pick a resistor that's equal to or less than the LDR, and you'll get a usable output. For example, for a 10K LDR use a 1K to 10K resistor.