Main > Main Forum

Potentiometer

Pages: << < (3/4) > >>

tetsujin:


--- Quote from: cholin on February 24, 2005, 06:20:11 pm ---So thats WAY to much then, whoa!  Are you sure about that though, because anything lower than 1k is measured in R, such as 10r, 600r, 999r, then it goes 1k, 100k, etc.

--- End quote ---

I guess "R" must be for "Ohms of resistance" or something, then...

ShinAce:

R is the equivalent of a decimal.

R10 is 0.1 ohms

500R is 500 ohm

as mentionned, k = 1000
m = 1 000 000

I'd say anything between 100 - 1k will be fine. Because if you use a 50 ohm pot, you will not be able to dim it by half. You'l dim it by about 10%. Vision is logarithmic. Better yet, get yourself a 1k audio(log) taper pot.

cholin:

Are you sure?  Well, I know you're sure because Ive seen your ideas in my other topics.  Would this do though?  How much would it dim?

http://futurlec.com/Potentiometers/POT1KA.shtml

ShinAce:

That's the one. It'll dim them down to about 30%. If you want even lower, go with a 5k. Hell yeah.

Are you sure about the 50 ohm resistor? Sounds like you're going for about 40+ mA. I used a 100 ohm, white led(measured 19 mA max) and a 2.5 k pot just now. Running off 5.2 V.

cholin:

Im running off 5 volts and using Japala's LED calculator to figure it out.  I put 5 volts as the supply, 4 volts as the drop and 20 mA for current which came out to 50 ohms.  This way, the MAX that can possible go to the LED is 4 volts @ 20 mA which is the highest rated for the LEDs I was looking at, although this may change because Im buying different LEDs from a different place, so I bought some 68 ohm ones just to be safe.  I obviously dont understand pots because I thought that the highest it would turn is the highest voltage output and the lowest it would turn would be 0 volts, I had no idea there were so many types!  I don't see how its relevant to get a 5000 ohm resistor basically :P  I thought that 1k would be good enough so that after like 1/4 of a turn it would already run out of current because there would be 250ohms resistance.  The two things I can't seem to understand:  Relays and Potentiometers.

Pages: << < (3/4) > >>

Go to full version