Skema Rangkaian Saklar Cahaya Otomatis

Skema Rangkaian Saklar Cahaya Otomatis ini sangat cocok untuk memberi penerangan sementara ketika suatu ruangan menjadi gelap akibat putusnya aliran listrik atau terjadi korsleting dan akan memberi penerangan selama jangka waktu tertentu antara 1 jam sampai dengan 5 jam bisa diatur.
Skema rangkaian:

Skema Rangkaian Saklar Cahaya Otomatis

The switch is a semiconductor relay S202DS2 and the oscillator is 4060.


Cara kerja rangkaian:
From the moment that T4 and T5 are opened, relay’s LED start to light and powers the lamp. As soon as one of the transistors is blocked the lamp will go OFF. The phototransistor T3 will be the one that blocks T5 if there is light that falls on T3. The T2′s base-emitter junction is connected in parallel with T3 and so will be blocked as long there is light. T2 will continuously resest IC1 whose counter outputs will be in “0″ state.

When the night falls R7 provides base current for T2 and the transistor starts to conduct. The counter can now starts to count the impulses from the internal oscillator and in this time the light will bulb will stay lit. After a time, when the output of Q13 goes in state “1″ T4 is blocked. This causes the relay’s LED to go off and the lamp too.

There is no need for external power supply because the light sensor switch is powered directly from the 220V mains. D1 … D5 diodes rectifies the voltage and C4 filters it.
C5 is working as a resistor so will need to have the working voltage of minimum 400V but the 630V is preferable.

S202DS2 is a Triac-Full-Wave-Output Optocoupler produced by Sharp Electronics in a TO-220 package.
The maximum peak-to-peak voltage is 600V, max on-state current is 8 Ampere and the input trigger current is 8 mA.

Caution! This circuit is powered directly from 220V. Attention will be given for appropriate isolation of the switch block.

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Rangkaian Alarm|Sensor Cahaya

Alarm|Sensor Cahaya

Rangkaian Alarm|Sensor Cahaya

This circuit is a loud alarm at the break of the daylight. The 555 timer IC is Used here. It is working as an astable multivibrator at a frequency of about 1kHz. This circuit can be used as an anti-burglar alarm in certain rooms, such as cupboard, cupboard in the open when the light will hit the circuit, so the alarm will be activate

When no light falls on the LDR, the transistor is pulled high by the variable resistor. Hence the transistor is OFF and the reset pin of the 555 is pulled low. Due the this the 555 is reset. When light falls on the LDR, its resistance decreases and pulls the bases of the transistor low hence turning it ON. This pulls the reset pin 4 of the 555 high and hence enables the 555 oscillator and a sound is Produced by the speakers. The 100K variable resistor has to be adjusted to set the light intensity That triggers the alarm.

IC 555 Pinning

function of each pin:

1. Ground, is the input pin of the negative DC voltage source
2. Trigger, the lower the negative input comparator (comparator B) that maintain low voltage oscillation capacitor in third Fcc and set RS flip-flop
3. Output, the output pin of the IC 555.
4. Reset, the pin which serves to reset the latch inside the IC which will affect the work to reset IC. This pin is connected to a PNP-type transistor gate, so the transistor will be active if given a logic low. Normally this pin is connected directly to avoid reset Fcc
5. Control Voltage, this pin serves to regulate the stability of the negative reference voltage input (comparator A). This pin can be left hanging, but to ensure the stability of the reference comparator A, usually associated with the order of about 10nF capacitor to pin groun
6. Threshold, this pin is connected to the positive input (comparator A) which will reset the RS flip-flop when the voltage on the capacitor started to exceed 2 / 3 Vc
7. Discharge, this pin is connected to an open collector transistor Q1 is connected to ground emitternya. Switching transistor serves to clamp the corresponding node to ground at a certain timing
8. VCC, this pin to receive a DC voltage supply. Usually will work optimally if given a 5-15V. the current supply can be viewed in a datasheet, which is around 10-15mA.

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