What is the 24V input coming from?
The ratio of resistors for the voltage divider is correct. The current flow through the resistor is defined by Ohm's law: V = I * R. With a voltage drop of 4 volts, and a resistance of 4 ohms, I = 1A.
Power is amperage * voltage, so a 1A current flow at 4 volts requires the resistor to dissipate 4 watts. That's a really healthy resistor you need.
A 4000 Ohm resistor would have 0.001A and would dissipate 0.004 watts.
the 24.65V is coming from a sensor.. DC signal.. hmm.. so the voltage divider could work with arduino?
meaning that it could sense the 4V as high?
I assume you are thinking of powering and arduino through a voltage divider. Don't even think about it, it is not the way to do it. The results are unbelievably poor and you waste a tone of power. Use a linear voltage regulator or switching regulator module.
hi there, nope.. im not gonna power my Arduino through this voltage divider.. i want the input pins to sense it as a "HIGH" or "LOW"
What I hear is that you want to sense the existence of a 24.5 volt 4 microamp signal. Is this to be an on-off signal that you want to input on a digital input pin?
4 microamps is not a lot to work with. At 24.5 volts, the current across a 6 megaohm resistor is 4 microamps. You could build a voltage divider with a 1.2 megaohm and 4.7 megaohm resistors to yield around 5V in the centre. Since you only have 4 microamps, I doubt this would make a useful input to the arduino.
For this small a signal, I suspect you would need an amplifier to deal with it. If it were me, I think I would use the signal to turn on a JFET, or feed it into a comparator with JFET inputs.
Hi there, yes.. i do.. you got me correctly.. but i think i measured the existing current wrongly..
I'm currently doing a project for my friend.. his SENSOR has a output voltage of 24.65 DC voltage.. BUT i wasn't sure about the current.. so i used my multimeter to check.. it displayed a reading of "4microamps"..
i think i got it wrongly as i remember that without a LOAD(resistor) there won't be current flowing through it.. ( from what i learnt from school, i've probably given the knowledge back to the teacher after my final exams. )
i've read the datasheet of the sensor.. it says OUTPUT: 30V 1A
Does that mean that i could draw a max of 30V and 1A out of the sensor signals?
if so.. how do i design my circuit so it does not burn out my resistors, damage the sensors and my arduino input pins?
Thank you guys for replying to this thread.
Really appreciate it man.. =)