Cheap emergency light circuit using D313

If you ever feel annoyed when the power failure while a working or a business. and in important area. Such as: the way up the ladder and in the bathroom could be dangerous, or shops at night you might be case it gets stolen the products. Emergency lighting is necessary to replace the main light during power failure.

Internal emergency light circuit will have battery backup. As usual This circuit will charge to stored in batteries. But when the electricity failure, it does the opposite is the battery will discharge into a lamp to provide light immediately.

How circuit works
Simple battery charger circuit with voltage charging.
The complete emergency lighting circuit is shown as circuit diagram below. Which core of the circuit is a simple charging system.
– Start the electricity AC220V 50Hz of house is entered through F1 (Fuse 1 Amp) to prevent damage. If the circuit malfunction.
– Later, pass through the switch S1 is turned on – off circuit.
– And the transformer T1 converts the voltage from AC220V to AC15V that voltage is also AC.
– When passed to the set of 4 diodes bridge D1-D4 into the direct current voltage (DC).
– But electric current is not smooth, Therefore the capacitor C1 is a smoothing filter power up.
– LED1 be used to display the power on of the circuit which R1 is a current limiting that suitable for LED1.
– The DC electric current to the transistor Q1 is connected as regular circuit. To control both the voltage and current properly. For charging the battery.

– The diodes D5 prevents flowing back of the battery’s current into the the circuit again.
– The voltage regulated are controlled to a constant, by value diode zener ZD1 15.6V, with the output voltage will be 15V (low voltage of the zener diode 0.6V).

– While battery voltage is zero volts or no power, R3 is used to set the maximum current of the circuit is about 500mA.

– the circuit will charge current battery steadily When the voltage of the battery, the charging current is reduced.

– Until the battery voltage is 13.8V or to full charge. The charger will not stop charging circuit as other
But current is flowing through the battery charge is low at about 100mA. To compensate for the loss of the battery to full power always.
– Normal relay contacts to the battery charging circuit. As any power failure, it will switch to battery connected to a load or a light bulb instead. And before to cutting the S2 switch on the lights to activate or not. When the electric current failure up.

Cheap emergency light circuit using D313

How to build

You can make PCB as Figure 2 is simple layout. Then you put all parts in PCB as components layout on Figure 3 which easy to really build. Please check error for wiring and various components or see carefully for is the polarity of the electrolytic capacitors and Diodes, transistor, lamp, tranformer and more.

Figure 2 The PCB layout.

Figure 3 the components layout

You may be packing all the equipment into the same box. With key ingredient is the B1 battery voltage 12V. In the prototype, the current size there is 4 AH, is the battery of sealed lead acid. It does not have any maintenance throughout the lifespan. It is more expensive than conventional batteries.
The transistor Q1 – 2SD313 is TO220 case, Vce=50V, Ic = 3A, power=25W. 2SD235 2SC1061 2SC789.

The tests and using.
After operates the circuit is complete into the box. Now that you the test used.
– This circuit is plugged into a power house. Then turn on the power switch S1 can hear the relay(RY1) click , start to connect the battery to the charging circuit and LED1 lights display power on.
– When switch off S1 to relay to the battery to the load and LED1 will off. Show that section cutting is loaded with circuit running. I will try to test the circuit. By the Connect the battery and the load circuit terminals to the output.
Then plug in the power cord about 1 hour, (if the battery is not charging). Try turning the power switch S1 current flows from the battery to the load. If the load is a lamp, it lights up. But 12V a lamp may not light up, do not panic. Because the battery is not charged until full. Must be plugged in for about 10-12 hours.
After that, try to cut off power switch S1 again. The lamp will be fully lit. If the test results show that both battery and charging circuit is functioning properly. You can find the right position to get it.

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mae andrews

How long does the battery life of these emergency lights? This is really useful. I think I should purchase at least 2 for my business.

The Porn Man

The battery life is about 6 month average.


was not really cleared about components…looking foward to construct my own power converter….Thanks


Write more, thats all I have to say. Literally, it seems as though you relied on the video to make your point. You obviously know what youre talking about, why throw away your intelligence on just posting videos to your site when you could be giving us something enlightening to read? fbbegdggek


This circuit keeps the relay energized all time, except power failure.The battery charging is also don’t stops after full charge. That results a damaged battery after a short period of time.I don’t know who exactly designed this circuit, but he has to learn a little about electronics before publishing such a stupid schematic.

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