Help with pot 271-0265 from Radio Shack

[LilBwana]

Hey guys, I was wondering if anyone could help me. I got the Radio Shack pot 271-0265 today and it is not labeled what the Vin or Vout is. Does anyone have experience with this model or know where I can find the layout? I was trying to follow Daedal's tutorial on building your own driver, and that seems to be where my holdup is.

Thanks in advance.

 

[lasersbee]

A potentiometer (pot)  is a resistor which has a wiper that moves across the
resistor to tap off any resistance value from Min to Max of that particular Pot
Value. The Pot has 3 pins... 2 at the extremes and one in the middle.
The Value of the Pot is found using a Multi Meter on the Ohms Scale measuring
the 2 pins at the extreme with the Multi Meter's Probes.
If you place the Multi Meter's probes on the center pin and any one of the
extreme pins and you move the Pot's shaft.... the resistance will change.

There is no Vin or Vout indicated on any Pot. You need to be able to read
the schematic to know how to connect it.

 

[GooeyGus]

there should be pin 1 2 and 3, labeled on the pot itself or on the packaging. Pin two is usually the 'wiper' and 1 and 3 are either end of the resistive material

 

[Cyparagon]

Even without the pins labeled, a simple resistive test with any multimeter will suffice. Also, Pin two is the center pin (98% of the time).

 

[LilBwana]

Sorry guys, this is my first build and first try at a DIY laser. All I've gotten so far, I hooked up a LED instead of the laser diode, and it seems to keep the same brightness irregardless of where I turn the pot. I have two different LD that I have hooked up and I get nothing, my guess is those diodes are fried. I am imagining also that the LD in a cd burner are not red diodes, so it wouldn't be worth trying those? Otherwise I will have to wait until I can get another diode. Kinda stinks because I am not sure if it is the driver, or the diode not working.

Thanks for your help though, (I can't give you the multimeter reading as I don't have one at the moment, I let my friend borrow it.)

 

[LilBwana]

there should be pin 1 2 and 3, labeled on the pot itself or on the packaging. Pin two is usually the 'wiper' and 1 and 3 are either end of the resistive material

This pins aren't labeled, and the bag it came in is of no use either, that would've made it too easy though :

 

[rkcstr]

This is what you got:
http://www.radioshack.com/product/index.jsp?productId=2062299&cp=

Of the three terminals, the middle one is the "wiper", or pin 2, while the outer terminals are either side of a conductive strip of resistive material, or pins 1 and 3. If you measure the resistance between the two outer, it will read about the full resistance rating of the pot. The middle terminal (or wiper) is basically attached to a small metal contact that moves along that resistive strip and depending on how far along it is relative to either side, the resistance will split relative to each outer terminal (ie, half way, you'd read ~12ohms between wiper and either outer terminal, while turned all the way in one direction, it would be ~0 between the wiper and one outer terminal and the full resistance, 25ohm between wiper and the other).

So... what this means is that you basically just need to connect pin 1 (or 3) as one "side" of the variable resistor, and pin 2 and the other "side", and connect pin 2 and the left over pin together (short which ever you didn't connect already to the wiper). This type of use is called "variable resistor" rather than "potentiometer", though the "pot" as its commonly called can act as either depending on how it is used.

There is no "in" or "out", resistance is resistance no matter the direction (in resistors anyway )

Got it? ;D