Now you want current?I'm trying to make a voltage sensor which can be used to sense voltage of 12V solar panel.
Why not add more parts? More money. More time. Greater chance of failure.why not use a voltage follower......
I'm trying to make a voltage sensor which can be used to sense voltage of 12V solar panel.
minimum acquisition time is 19.72 us
At least use a R-R op-amp. Many amps will not work well then the output is near ground or supply. Many will not work when the input is with in 2 volts of supply or ground. It is common to find people (with a 5V supply) trying to measure 1 volt and the amp can't do that. "common mode input voltage range"I don't think I need to use a bipolar supply for the op-amp because
OKkeep your answers to the point
yesThe gain of 610 mV/A would mean that when input current is +5A then the output voltage, Vout, is 3.05V, right?
noDo I have it correct?
yesCorrect?
yesDo I have it right?
yesLM321, can I use LM741
From the circuit, it looks like that the op-amp is operating in inverting configuration therefore I think when the input current is +5A then Vout is going to be -3.05V. Do I have it correct? If I'm correct then another op-amp in inverting configuration with unity gain is required to make the Vout positive. Correct?
Short answer is you need rail to rail op amps!
The LM741 is vary old and not too good.Thank you.
Okay. LM741 is very common and is available globally everywhere but it's not a rail to rail op-amp. Could you please let me know about some common rail to rail op-amp so that I could look them up in the market? Thanks.
Regards
PG
Voltage Sensor:
For most PIC microcontrollers 10k is the maximum recommended source impedance but the acquisition time can be reduced by reducing the size of source impedance. For instance, this reference gives that minimum acquisition time is 19.72 us when Rs is 10 kOhm (page #428) and minimum acquisition time is 10.61 us when Rs is at its allowed minimum value that is 50 ohm (page #429). One option to reduce to the source impedance is to use a voltage follower like this but this increases chance of failure. But, if R2 is reduced to 1k in the circuit shown in post #2 above then R1 should also be reduce to 3k, this would load the panel quite significantly and consume much current. Does it make sense?
You can find newer single voltage op amps that go close to rail to rail, thats all you really need.I don't think I need to use a bipolar supply for the R-R op-amp because I'm not going to detect negative voltage therefore I have simply connected the negative supply input to the ground in this circuit.Please confirm it. (In the picture 741 is shown, please just ignore it.)
You can also see that I have labelled the ground as Vss because I think that the node needs to b connected to Vss of the microcontroller to complete the circuit. Could you please confirm it whether I have it right?
Do you really need to increase the output voltage??Current Sensor:
You can find this circuit on page #12 of the datasheet. The circuit increases the gain to 610 mV/A from 185 mV/A for a +/-5A sensor (in the datasheet, it's part number is ACS712ELCTR-05B-T).
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