Simple light controller circuit using CD40106

This is Simple light controller circuit that is controlled light-activate. Which use the inverter gate IC-40106 as main components in compare and controlled switches, and common phototransistors as sensors

The Operation of switch has several forms. The most basic way is to press the switch directly. If modern must be controlling by Infrared light or remote control. As well as uses radio frequency to control turn on / off switch. Even common light so can control turning on / off switch.

Light sensor controller using phototransistors

The working principle
The circuit in Figure 1 is the mini switch controlled with light which use phototransistor as a light receiver there are a schmitt trigger IC(CD40106) as drive an output current to load or the external circuit. It can provide output current up to 25 milliamperes are circuit that use a few together components, Can be directly connected to small loads. or to drive the relay or an optocoupler type. to drive the load that use with AC volts or also DC high voltage.

The working of circuit when has light to the phototransistor-Q1 cause has current flow between collector-emitter junction, and has voltage drop across a potentiometer-VR1 as voltage “high” to trigger to a first schmitt trigger-IC1/6 until output is “low”. And have others five schmitt triggers that parallel into the inverter gate provide voltage output is “high”. The connecting in parallel to the maximum drive current or the about 25 mA.

Figure 1 The mini switch controlled with light using CD40106

The resistor-R1 and capacitor-C1 are connected into the RC networks to prevent noise, which may be inserted. If the problem of noise. may add capacitance-C1 little up. The potentiometer-VR1 to adjust a sensitivity in as switch of Q1. When has a lot light to it. The circuit can be used with the power supply up to 16 V

How to build this projects.
This project is not used a few components so can assemble on the universal PCB board as Figure 2.
In the assembly circuit,Starting equipment lowest first to Beautiful and easy to the assembly. Start from Diode and then resistors and sort of high continuously.


Figure 2 the components layout of this projects

For the device has various polarity should be careful in the assembly circuit. Before placing these components will must set the polarity at PCB and the part match together because If you put backward, may cause equipment or circuit damage.

The components list
Resistors size ¼ W +5%
C1, C2________0.1uF 50V____Polyester capacitors
Q1———–SFH309-6 ____Photo transistors
IC1_______CD40106__CMOS Hex Schmitt Triggers
Universal PCB board

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This Post Has 2 Comments

  1. Hi, when you turn VR1 to min = 0 ohm, the phototrasistor will be broken. It will connected to full current from the power. You have to connect one more resistor in series with it…
    Sorry for my bad english… 😉

  2. it’s excelenet.thanks for you and your website.

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