Please check the calculations I did for the voltage divider in my auto power supply. (sensor, Accord)

[Denjiro14]

I'm constructing a voltage divider from a Bobcat Skidsteer to power an Arduino nano clone. Two ultrasonic sensors, a 20x4 LCD, and a buzzer will all be functional on the copy.

R1 = 250ohms R2 = 500ohms RT=750 ohms

The Bobcat's voltage was 13.8V when I measured it at full throttle, but as a safety precaution, I decided my maximum voltage could be 14.5V.

I = (14.5V)/(750ohms) = 0.0193A when V=IR is used. The Nano clone could receive up to 0.0193A from this.

Voltage drop at R1 equals (250 ohms) (0.0193 A) = 4.83V Voltage drop at R2 equals (500 ohms)(0.0193A) = 9.65V

The maximum voltage that may be delivered to the Arduino Nano clone is 9.65V.

Now, in order to see if the resistors can withstand this,

According to what I've read, those tiny resistors can tolerate a maximum power of 1/8 to 1/4 watt.

[OutdoorLover]

I haven't used V= IR since undergrad physics, so, pretty rusty, but yes, I recall that, and those sound like the right standard units, just eyeballing the numbers anyway, things look good.

P.S. There is also the power equation (Watts Law), P= IV

[RetireinPA]

This is the future, you are making this too hard...what voltage does VCC on the nano thingie want? nextly, what current CAN it use? google up the 78M12, 10, 8 and 5...those are all 1 amp voltage regulators that need as little as 1.2v over rating.


If that is not matching up (and Im fuzzy that it cannot) then google up an LM317 regulator circuit. I once used 2 of these to source the needed power for a class D amp that had to have 24v max but the unit power supply was 34v rails...


peace 0h cake.


BTW - GE used to use resistors to get the right DC drop on its 'cubes' (the AM, or AMFM clock radios from the 70;s) it was a MEATY cement resistor as much current got them hot..if you dont have at least 3w resistors in stock, dont do this.


If current is low, just use a zener. if current needs to be higher, but voltage fixed, use a zener to drive the base of a to220 power trans like a tip41 etc.





ps believe it or not it was actually PIE (P= I * E where E was voltage, and EIR - E = I*R) and if you have fun with algebra P = I^2 * r. Im betting the nano lives on 5v just fine, order a 7805 or 78M05 and a few supporting thingies. If you are close by I got the crap in stock.