2 Small UPS circuits diagram

There is a UPS circuit diagram for emergency backup battery systems.  It can be applied to many applications. When the power goes, the battery can provide backup power automatically.

Two circuits ideas below..

Small UPS 6V backup

This power supply circuit system consists of a transformer, a bridge rectifier, and an electrolytic capacitor. And there is a Zener diode for controller the output power transistor(BD135 NPN) of this circuit and will be determined at a constant voltage of 7.5 volts.


The Backup battery 7.5V(1.5Vx5) in series with D2 and both are connected to across the output terminal. The voltage drop across D2 serves to reduce the voltage level of the power supply down to about 7V.

When the current from the AC main comes to a circuit. The R2 serves to charge the dry batteries or the battery power is accumulated in the circuit, to prevent over-charging R2 will take control. By simply keep the current flowing from the battery runs out while using the full functionality of the home.

The resistance can be calculated. By dividing the voltage between the Zener diode and battery, with value battery voltage for safety.

Small Uninterruptible Power Supply UPS Circuit

Figure 1: Small Uninterruptible Power Supply UPS Circuit

The detail parts

BD135_NPN transistor
R1,R2_1K, 0.5W Resistors
C1_1,000μF 25V, electrolytic type.
C2_100μF 25V, electrolytic type.
ZD1_ Zener diode 8.2 volt 0.5 watt
D1_ The Diode 1N4001 (50 volt 1amp)
T1_ Transformer 0.5A 10V
B1_ AA battery 1.5V x 5 pcs

How it builds.

We use the equipment very small, so it is not necessary to make printed circuit boards. We can all soldering electronics (except for transformer) on the prototype board small size.

Choose a charger for the battery size AA 1.5Vx5 = 7.5V or size 6-volt lead-acid battery, it works great as well. This circuit can supply enough current to 500mA circuit applications, such as a small digital clock. Small emergency lighting system and more.

6V backup battery regulator using 7805

This simple and cheap 6-volt power supply circuits with a 6V backup battery system or 6V ups circuit diagram.

The AC power 220V is entered to through input of transformer-T1 to reduce voltage as 9VAC, then wire connected to four diode D1-D4 as bridge rectifier became to 11VDC.

Then, the current is filtered to dc voltage that low ripple output and then the voltage is regulated to a 6VDC constant voltage by IC-KA7805( IC-7805 type).

In normal it is used for 5 volts only but now we add two resistors to the determined output voltage is 6 volt and passed through diode 1N4002-D6 to output is 6 volt.

The current operate via the diode D1 and R3 to charge the 6 volt battery Ni-cad type.

When not have the electrical supply line, the current of the battery are passed through D7 and S1 to output automatically.

The LED1 and R4-470ohm for display power on of this circuit.

6V Backup Battery Power Supply Regulator using IC-7805

Part list
IC1_LM7805,KA7805_DC regulator 5V
Electrolytic Capacitors
C1_2,200μF 25V
C2_33μF 25V
C3_1,000μF 25V
D1-D7_1N4002_Diode 100V 1A
LED1_LED any color as you like
0.25W resistor
Sw1_on/off switch
T1_Transformer, 1A output 9V
F1_Fuse 0.5A

Other circuits involved.

You can see:  Regulator 5V-6V-9V-12V at 1A using IC 78xx
And see more:

  1. Basic Dual DC Power Supply 6V
  2. Change the output voltage of  IC-7805  diode

What’s more? You can look other power supply circuits: Click Here

Related Posts


I always try to make Electronics Learning Easy.

Notify of

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Inline Feedbacks
View all comments
Close Menu