Are all potentiometers equal?

[vawinesnob]

I broke the potentiometer on my Bakatronics PWM before I was able to test the boil kettle. I picked up a new pot at Radio Shack and during testing found that the element fires but I have no control. I'm wondering if the pot is different or if I've made a mistake putting together the PWM?

All hep and advice appreciated.

 

[kellzey]

Uhhh.... what were the specs of the POT you used?

No, potentiometers have OHM ratings... did you buy with the correct OHM rating.

Also, the terminals on the pot should be connected properly. Usually the signal source (power) is connected to the outside terminal and the component you are controlling is connected in the middle.

Here is good visual

http://www.allaboutcircuits.com/vol_6/chpt_3/7.html

 

[ChuckO]

Some pots have a linear resistance over the motion range, while other pots change at a logarithmic rate. You probably want to use a linear version.

 

[skinydipper]

This is the kit from Bakatronics: http://www.bakatronics.com/shop/item.aspx?itemid=383

I don't see any markings on the pot, nor the instructions. I bought a linear resistance pot from Radio Shack, I don't have it with me right now so I don't know what the ohm rating is. Does it sound like I have too high/low resistance?

 

[Iowabeerguy]

The Bakatronics Pot is a 500k Linear type. My original one was broken also - problem I had was finding one that soldered into the board. Might check with Bakaronics to see if you can order one direct from them.

 

[thargrav]

If it's soldered into the board they will sell you a new board or have you send that one in for repair.

 

[vawinesnob]

I went back to Radio Shack and they didn't have a 500k pot so I bout a 100k pot. Installed the 100k and still same problem. Read every post in the "PWM Show me how" thread. Read about potentiometers in the link in this thread, checked that my diodes were installed in the right direction. Went back to Radio Shack for a new 555 timer, installed it and still same problem. Started checking all solder connections and found one pin on the 555 was bad, fixed it and everything worked fine.

Thank you everyone for your input.