# I have a USB input, I wanted to connect a battery and from battery it should go to load. Could some one link to the diagram?

#### kunduruswaroop

Joined Jan 2, 2021
6

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#### sghioto

Joined Dec 31, 2017
5,079
What does that module do and what are the two red wires at the bottom connected to?

#### kunduruswaroop

Joined Jan 2, 2021
6
What does that module do and what are the two red wires at the bottom connected to?

I don't know much about the connection. The 2 red wires should be load.

#### sghioto

Joined Dec 31, 2017
5,079
What does the module do?
What is the USB input for?

#### kunduruswaroop

Joined Jan 2, 2021
6
input usb take in power,
is should charge battery and when battery is full it should charge a wall clock with 2 AAA battries. I wanted this circuit to replace wall clock batteries.

#### sghioto

Joined Dec 31, 2017
5,079
That certainly explains the photo. NOT!
In that case why not just power the clock from the USB?

#### kunduruswaroop

Joined Jan 2, 2021
6
That certainly explains the photo. NOT!
In that case why not just power the clock from the USB?
Yes, That save time and solution is simple. Agreed.

But I am learning to make a circuit for the clock to use a backup (battery) power when there is power outage.

What all the 3 (Black, Red and Yellow ) wires indicate?

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#### Tonyr1084

Joined Sep 24, 2015
7,543
is should charge battery and when battery is full it should charge a wall clock with 2 AAA battries. I wanted this circuit to replace wall clock batteries.
To RE-quote you - "It should charge a battery. When full it should power a wall clock that has two AAA batteries."

If your wall clock runs on two AAA batteries then why would you need USB power? First, we don't know what the circuitry on the board is or does. We don't know if it runs on 3.3 volts or on 5 volts. The clock, powered by two batteries runs on a varying voltage of around 3 volts and lower as the batteries drain. 5 volts might be too much for the clock circuitry.

When you say "should charge battery" what kind of battery are you talking about? You need to plan out how that battery is going to be charged. Just because you have power from a USB doesn't mean it's suitable for charging any rechargeable battery. Improperly charging some batteries can result in excitement, fire and a chance to remodel a room in the house.

We understand you want to accomplish something. Sometimes people come here for advice, and of those who come - all are welcome to be here and ask and learn. My impression - and forgive me if I'm wrong - is that you don't understand enough about electronics to take on this task. So again I ask, if your clock runs on batteries then why do you need to replace the batteries with a rechargeable battery? I have a wall clock that runs on two AA batteries. Every few years I have to replace the batteries. The pain with that is having to reprogram the clock after removing the dying batteries. I installed a capacitor that holds enough power long enough to quickly change the batteries in the clock without it losing time or needing reprogramming.

#### MisterBill2

Joined Jan 23, 2018
16,469
In some parts of the world it is difficult to get a battery that would run a wall clock for a week, even,
I have considered schemes to power a wall clock from the mains and have a super-cpacitor as a backup, and no USB connector, wires, or supply should be involved, because USB is a poor choice for the application. A typical wall clock is powered by either 1 1/2 volts or possibly 3 volts, although that is unusual.
The very simple low current supply for a clock will be a low voltage wall wart, either AC or DC, a series diode and resistor charging a filter capacitor, and a shunt regulator consisting of either 2, 4, or maybe 5 forward biased diodes similar to a 1N4001, so that the voltage would be, in theory, either 1.4 volts, 2.8 volts, or 3.5 volts if 5 diodes are in series. No USB connector no circuit board, and it can all fit into the battery compartment with only the wall wart external.