Diagram Guide

This is a photo detector, a detector with TTL output light that can be used in projects for Arduino. This schema offers low output level when there is enough light, or a light that triggers the system. He can give a command, for example, turn on the lights when it gets dark and off when clear. The output is compatible with TTL level and gives low (LO) when Q1 phototransistor detects light. RV1 with a trimpot, we can adjust the sensitivity.

 Photo Detector with TTL Output Circuit Diagram



Parts List
R1 = 270 Ohm
R2-5 = 1K ohm
R3 = 10K ohm
R4 = 100 ohm
RV1 = 10K ohm
Q1 = BP103 Siemens Phototransistor
IC1 CA3130
C1-2 = 100V 100nF ceramic
IC2 = 74HCT13
D1 = 1N4148-2