Photo resistor up close.
Basic components are a photo resistor, LED, and shrink wrap tubing.
Place components inside shrink wrap, face to face.
Simply apply heat with a heat gun.
Vactrol! The LED can be biased for brightness using the appropriate resistor value in series.
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Vactrols - DIY
A vactrol consists of two components incorporated into one package: a light-emitting diode (LED), and a photoresistor (a resistor whose resistance drops when it is exposed to light). Applying a voltage to the LED causes current to pass through it and light to be emitted, which falls on the photoresistor. If a voltage is applied to the photoresistor, it will develop a current which is proportional to the voltage applied to the LED. This makes the photoresistor, in effect, a voltage-controlled resistor.
Vactrols are expensive and often hard to find these days. So I thought I'd try and make some of my own.
