hi,In this schematic:
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Can R2 and R3 be combined into 1 940 ohm resistor(if there was a resistor of that value). Or is there a reason they are split into 2?
Already answered in my Post above yours.Am I correct in thinking you could just get rid of R2 and R3?
Am I correct in thinking you could just get rid of R2 and R3?
edit: ah, that makes sense.
You could providing on that 741 circuit you didnt turn the pot to the top [V+] end.Am I correct in thinking you could just get rid of R2 and R3?
hi,With a supply voltage of less than 15 volts there is no limit to the input range of a LM741. R2 and R3 can be eliminated, however, the circuit will be very difficult to adjust/calibrate with using and expensive 10 turn potentiometer. Leave R2 and 3 in the circuit and you will have not problem using a cheap 1 turn pot.
R2 and R3 would have to each be much bigger relative to the 10k of P1 in order to desensitize wiper movement along P1. As shown, R2+R3 is less than 10% of 10K, so the whole "expand the range of P1" discussion is moot.... R2 and R3 can be eliminated, however, the circuit will be very difficult to adjust/calibrate with using and expensive 10 turn potentiometer. Leave R2 and 3 in the circuit and you will have not problem using a cheap 1 turn pot.
As shown in the original circuit, the voltage at the non-inv input could be anywhere from ~1V to about ~11V, depending on where the wiper of P1 is.In the diagram the + voltage is 12volts. Does that mean the non-Inverting input of the op amp is seeing 6?
If you left out R2,R3, the entire 12V would appear end-to-end across the 10K pot. The non-inv input could then be adjusted from 0V to 12V as the wiper is moved.If so is that by design? Because some of you were saying you could basically get rid of R2/R3, but if so would it not then see 12volts? Or does that not really matter?
Sorry bear with me here. So if R2 and R3 are gone, the noninverting would see the full 12v? How can it see 0->12V then? Doesn't the pot only limit current? Not voltage?As shown in the original circuit, the voltage at the non-inv input could be anywhere from ~1V to about ~11V, depending on where the wiper of P1 is.
If you left out R2,R3, the entire 12V would appear end-to-end across the 10K pot. The non-inv input could then be adjusted from 0V to 12V as the wiper is moved.
The discussion about current limiting into the non-inv input of the 741 has to do with what happens as the wiper is run all the way up, and the input goes to the same voltage as the 741's V+ pin?
Read up on "Voltage Divider". The Pot is a voltage divider consisting of the resistance from the top end of the pot to the wiper, and the resistance from the wiper to the bottom end. The wiper can be moved all the way from the bottom to the top, so the wiper voltage "taps off" any voltage from 0 to 12V as the wiper is moved.Sorry bear with me here. So if R2 and R3 are gone, the noninverting would see the full 12v? How can it see 0->12V then? Doesn't the pot only limit current? Not voltage?
It will work as long as the device connected does not draw appreciable current. This scheme is sufficient for producing bias voltages. For any reasoable load, you'll need something more sophisticated.So with voltage dividers. Say you have a 9volt battery. Could you use 2 resistors to make it 5 volts and connect the voltage supply to a circuit in between those 2.
Basically a makeshift voltage regulator. Or does that not really work?