The light meter circuit is a tool, measure the quantity of light, widely used to a photography, To decide the correctness of the exposure.
Sometimes, we are use with other works, such as my son likes to use in science experiments, which do not need to have high quality.
This simple light meter in figure 1 is an example circuit form LM134/LM234/LM334 datasheet of National Semiconductor (most popular IC), It takes very little equipment,
Features of the circuit, when there is a lot of light levels, an ammeter will show a high current, but a little light it will lower the current.
We use the light sensor device is the LDR( Light Dependent Resistors) which Normally the resistance of an LDR is very high, but when the light hits it, that has a lower resistance.
The LM334z is 3-Terminal Adjustable Current Sources, that the output of 1µA to 10mA with a resistor between pin 1 and 3, and used the power supply voltage input is a wide range of 1V to 40V.
The ammeter may be used the 0-1mA Analog DC Current Panel Meter Ammeter at amazon.com it low cost and FREE Super Saver Shipping.
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