Small UPS Circuit for Router Backup

Never lose connection again, make this Small UPS Circuit for Router Backup.

When a power cut occurs, the internet goes off and the router and modem stop working; therefore, a small UPS can solve this problem.

This give backup to DSL modem and WiFi router and also this circuit is with simple parts, easy to build and with low cost.

Circuit Working:

Parts List:

Components	Values	Quantity
Resistors	2.6k	1
	250Ω	1
Capacitors	Ceramic 0.1µF	1
	Electrolytic 1µF 25V	1
Semiconductors	IC LM338T Voltage Regulator	1
	Diode 1N5404	3
	Battery 12V 7Ah Lead Acid	1

The above circuit diagram can power DSL or WiFi routers and it can also run any device that works on 9V or 10V.

Also, input supply 15V to 32V DC and IC LM338T work as adjustable regulator.

Then output voltage set by R1 and R2, capacitor C1 filter noise at input and capacitor C2 smooth output; after that, diodes D1 to D3 give isolation and drop voltage

Now one output goes to 12V battery charging and another output goes to router or modem 9V to 10V and finally, battery give backup when main power fail.

Formulas:

The following formulas help calculate the values used in the Small UPS Circuit for Router Backup:

Output voltage Vout = 1.25 * (1 + R2/R1)

here.

• Vout​ is the output voltage of the LM317
• 1.25 V is the reference voltage of LM317
• R1 is the resistor between Adj pin and ground
• R2 is the resistor between Vout and Adj pin

How to Build:

To build a Small UPS Circuit for Router Backup follow the below steps:

• First, gather all the parts as shown in circuit diagram.
• Next, LM338T pin 1 adj connect to R1 and R2.
• Then pin 2 input connect to DC supply + through C1.
• After that, pin 3 output connect to R2, capacitor C2, D1 To D3 diodes chain.
• Also, battery connect at output between diodes D1 and D2.
• Now connect the router to the output end after the diodes and connect the negative line to the common ground.

Conclusion:

Overall, this Small UPS Circuit for Router Backup is small and useful, it keep modem and router alive in power cut.

Also, we can build it with only a few parts, and we do not need a large inverter; moreover, the internet stays ON even when the electricity goes out.