# Voltage Stabilization?

Discussion in 'General Electronics Discussion' started by icor1031, Apr 27, 2010.

1. ### icor1031

65
0
Apr 27, 2010
At 3.1v and 150ohm I have .1441..?

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,411
2,779
Jan 21, 2010
Aaah, no.

Try using the values I gave you.

25mA (0.025A) and the various resistors.

3. ### icor1031

65
0
Apr 27, 2010
31.875
29.375
16.875
10.000

25ma and 510o, 470o, 270o, 160o...?

I probably don't understand what ^ means in math.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,411
2,779
Jan 21, 2010
I^2 means I squared (I x I)

That should get you more reasonable answers

5. ### icor1031

65
0
Apr 27, 2010
That's what I thought I did..

Is the first one 19921875?

6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,411
2,779
Jan 21, 2010
let me work through one with you.

P = I^2 R
= 0.025 * 0.025 * 150 (for 25mA through a 150 ohm resistor)
= 0.000625 * 150
= 0.09375

So that resistor at 25mA is dissipating 0.09 Watts. Unless other constraints existed I would use a 1/4 W resistor.

7. ### icor1031

65
0
Apr 27, 2010
~~Try connecting 1 in series with a 510 ohm resistor,
...
So, my first answer was right.. just had the wrong decimal placement.

I don't see how to do it with 2 or 3 LEDs, though. :S

Last edited: Apr 28, 2010
8. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,411
2,779
Jan 21, 2010
I didn't see a correct answer from you at all. Neither did I see the results of your calculation for the other resistor values.

I know you didn't bother to answer me.

9. ### icor1031

65
0
Apr 27, 2010
~~Did you wire them in series or parallel?

*I wired 3 LEDs in series... pos power to pos led, neg led to pos led, neg led to pos led, neg led to neg wire.

~~~Try connecting 1 in series with a 510 ohm resistor,

**31.875

~I didn't see a correct answer from you at all. Neither did I see the results of your calculation for the other resistor values.

I calculated that the same way you calculated this (which I came up with the same answer)

~P = I^2 R
~= 0.025 * 0.025 * 150 (for 25mA through a 150 ohm resistor)
~= 0.000625 * 150
~= 0.09375

10. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,411
2,779
Jan 21, 2010
OK, so the answer is YES you wired them in series, but NO, not like the link showed (i.e. with a resistor)

So the wattage for each of the 4 resistors would be?