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For the Op-amp on the top right:
LM741 Chip
Application:
To protect your battery voltage from over-discharging.
Whenever the led lights up,you must stop using the battery and go for recharging...
So the LM741 chip is an 8-pin. We only connect 5 out of the 8 pins.
Pin 1 is a NC (Not Connect) and pins 1 and 5 are offset nulls, which we don't connect for this circuit.
Now to power the circuit, we connect , pin 7 to a possitive +5V and pin 4 to a nagative 0V to ground.
This establishes power to the LM741 chip.
Next, we have the 2 inputs of the op-amp (Lm741).
We connect our reference or threshood voltage which is always constant at 5V to the Non-inverting terminal (+), which is pin 2.
This is the voltage that will form the threshold voltage for the circuit.(5V)
To the Inverting terminal(-), we connect the battery possitive-voltage signal we wanted to test or protected!
Than ground the nagative terminal of the battery.
If the battery voltage at the Inverting(-) terminal is less than at the threshold voltage at the non-inverting terminal, the output will turn on,(red led gives a warning of a falling voltage) because the
non-Inverting(+) is greater or higher inverting terminal(-)
+ > - , output = possitive.
However, once the voltage at the Inverting terminal(-) goes above the voltage at the non-inverting terminal, then the output, at pin 5, will turn off, because the inverting terminal(-) is now greater or higher than the non-inverting terminal (+)!
- > + , output = nagative = led off......
Here,the battery began to or is charged up.....
And, lastly, to the output pin of the LM741, which is pin 5, we connect our output which in this case is an LED as an indicator light along with a 150Ω current-limiting resistor so that the 2V LED doesn't blow out.
NOTE:
1.the possitive terminal of the testing or protected-battery must be connected to the inverting terminal(-) of the op-amp!
2.Reference or threshood terminal must be connected to the non-inverting terminal(+) of the op-amp!
But the diagram at the top left is more explainatory and better with regards to
the monitoring of falling battery voltage onder a load.
You can easily adjust the voltage of the testing battery through the the potentiometer which replicates falling battery votage.
Here,the reference or threshood voltage is 11.00V(theproteced battery voltage must be allowed to drop below 11.00V )
This completes all the connections for our circuit.
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