Mini emergency light circuits

This is first Mini emergency light circuit of my son. It is very small, use LED display when power outage,use transistor instead relay use AA battery charger.

How it works

As Figure 1; Tiny emergency Light circuit use a few parts include the two AA nickel-metal hydride batteries, for store enough energy to drive a small lamp.


It works like the general emergency light; it fixtures are used to automatically provide lighting in the event of a power outage.

1. The charger section electrical energy storage in normal conditions.
2. The controller to drive the lamps light up when is power outage.

The tiny emergency light are also special, do not uses the relay to ON-OFF the lamp. But use the transistor, it acts as the switch ON-OFF instead, may be called a solid-state emergency light was.

Working began from AC power is fed into the circuit.

To fuse F1 as a blocker than the current flow may be caused by the mistakes of the circuit.

The transformer T1 will reduce the AC voltage 220V to lower about 6 volts. The AC low voltage will be rectified by diode D1 as half rectifier form. Then DC voltage will flow to resistor R1 and D2 to the battery. The charger current of circuit will set at 55 mA

When plugged into the circuit, the LEDs are not lit. Because the base lead of transistor Q1 get Reverse Bias has higher voltage than the emitter leads. The transistor will “OFF” own conduct. But when the power outage at the base leg voltage is reduced.

He does not uses the lamp because he does not has them, but he use the red super bright LED instead.

Since resistor R2 full down pull current makes transistor “ON” have current flow from the battery. Makes LED glow up. The current from battery will do not feedback to the transformer. Because there is diode D2 block the current by connected the reverse bias between the battery and transformer.

Parts you will need

Q1: BD140, PNP transistor
C1: 470uF 16V, Electrolytic capacitors
R1: 22 ohms 1W
R2: 560 ohms
D1,D2: 1N4007 Diode
T1: 6V 0.5A transformer
and other

How to build

He makes this circuit on universal PCB Board as Figure 2 to Figure 4. Because it is easy circuit.

Easy to put parts on perforated PC board
Easy to put parts on perforated PC board

Soldering pins
Soldering pins

Cut lead of parts
Cut lead of parts

Actual-size of Single-sided Copper PCB layout
But you build it on PCB you can use PCB layout as Figure 5 Actual-size of Single-sided Copper PCB layout

the components layouts
and Figure 6 is the components layouts

Because we do not have a 2 AA battery holder. We so soldering wires directly as Figure 7
soldering wires directly

and use electrical tape as Figure 8.
Use electrical tape

To short-circuit protection

To short-circuit protection

Drilling for mounting LEDs
Drilling for mounting LEDs, they use only 3 LEDs, because of the low power consumption.

Install all parts to the versatile box.
Install all parts to the versatile box. Then use hot glue stick. the LED legs with the box.

Look inside this machine
Look inside this machine

How to use and application

He installs this corridor. He tested the device without connecting to power. If the battery power is normal and the normal LED. The LEDs will be lit up immediately.

But when the plug and LEDs are not illuminated. The charge current can be checked from voltage across the resistor R1 is calculated by the Ohm’s law.

I (current) = E (voltage) / R (resistance)

Assuming the voltage drop across the resistor R1 (22 ohms) at 1 volts charging current values are equal:
= 1 volts / 22 ohms
= 0.045 Amperes
or equals 45mA
This circuit uses the charging current 50-60mA.

When building this project completed Try it together as video below.

Simple emergency light circuit with charger

This is Simple emergency light circuit with charger that light on 30 minutes after the power outage, so use normal transistor as base of circuit.

At the time of power failure. Especially during the night. Many people do not like the dark. Emergency lighting systems on the market, it has expensive. We make a emergency lights with a simple electronic circuit. But it is enough to use it to some degree. This circuit makes light bulbs for nearly 30 minutes after the power outage.

As Figure 1 First of circuit that use to drive the lamp, which consists of a transistor that work as switches, by has Q1 is driver. The transistor -Q2 acts as the signal amplifiers for provides to lamps- LP1-LP3 glow up.

the 30-minutes-emergency-lighting
Figure 1 the 30-minutes-emergency-lighting

The second is the ac line voltage detector and the battery charger. By transistor-Q1 will open circuit when voltage from AC line power still. (at its base will has voltage not exceeds 0.7V) and when not have voltage from power supply Q1 will close switch down, cause the lamps glow.

The low voltage power supply can be build the low voltage transformers of center trap type. And rectifier diode D1-D4 to the secondary of transformer. which has 0V another position.

If voltage of AC line power still, the first positive half cycle side, current will flow through the transformer to fuse and through battery. which is A nickel-metal hydride battery to charge the battery by current is limited with R3 current will flow back to point 0V through diode D1 or D2

Another half cycle later. current will flow like the first half cycle. but will flow to transformer by through Diode D3 or D4. The driver transistor will still hold switch off.

When not have ac line power (power outage) current will flow from the positive polarity of battery through resistors-R1 to bias to base of Q1, cause Q1 conduct current, Q2 so also conduct current. The lamp so glow up as during time equals voltage of battery still which about nearly 30 minutes

How to builds
This project use a normal components so can assemble on the universal PCB board. With the wiring and various components can view of the example in Figure 2. We should check carefully the polarity of the electrolytic capacitors, diodes, transistor correctly.

The components list
0.5W Resistors
R1-100 ohms
R2-33 ohms
R3-10 ohms, 2W Resistor
C1-100uF 25V Electrolyte capacitors
D1-D4-1N4001, 50V 1A Diode
LP1-LP3-Lamp, 3.5V 300 mA

The LED emergency light circuit without a transformer

This mini LED emergency light circuit without transformer is used to automatically give lighting when ac line power goes out. Which they consist of one lamp, a battery, and a low voltage sensor. This project’s design takes advantage of simple circuit techniques and cheap.

Special feature:
1. Small-sized: output with 2.4V 5W lamp or 3V LED and a 3V battery.
2. No transformer is so Lightweight and easy to build.
3. No relay so be Silent and small.
4. etc.

How it works

Mini Emergency Light by 9013 transistor

To begin with, we use a 4-5V dc power supply without a transformer. Next, the AC 220V input to passed trough R1 to cut current down and D1 to rectifier AC to DC in half-wave type. Then, the dc pulse or fluctuating signal is smoothed with C1-capacitor. Which has voltage dropped across of 4.5Vdc

And then SW1 is used to turn on-off the next circuit as a sensor, control, battery charger, and lamp circuit. First of all, in normally power the lamp go out not light since current pass to R4 to the base of Q1 cause it is bias so high current flow through D2-diode, R5-resistor to collector-emitter of Q1. Thus not has a current bias to the base of Q2, Q3 ( Darlington transistor) cause they do not conduct current, so not has current pass Lamp, it so not light.

Note: However, this circuit is not suitable for practical applications. Because of the small size and short duration.Cheap emergency lights using D313


And later the power AC line goes out, So not has current through S1, and then current from 3V battery not current through D2 be due to diode not allow current as is a one-way street. It will not work if you put it in backward. And making Q1 does not work.

But this battery current will flow to R5 through base Q2, Q3 they so bias current is a result of high current flow to Lamp glow light up at once.

Friends can use Nicad Battery or NiMH battery the size is 1.2V x 2 gives the light has just enough. This circuit can charge automatically batterys.

How to builds
This circuit is easy you so can build them with yourself on universal PCB board.

The detail components

Q1,Q2,Q3: C9014,C9013___1A 50V__NPN transistor
D1: 1N4148 75V 150mA Diodes
D2: 1N4004 400V 1A Diodes
L1: 2.4V 5W Lamp
L2: Neon Lamp
S1: Slider Switch
C1: 47µF 50V Electrolytic Capacitors
R1: 220K, 1/2W resistors
R2: 33K, 1W resistors
R3: 10K, 1/2W resistors
R4: 1K, 1/2W resistors
R5: 15K, 1/2W resistors
B1: 3V battery (AA 1.2V)

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I always try to make Electronics Learning Easy.

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Very nice,how to get attach with you to get like this circuits.

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