El Cheapo II resistor question

I just got an Oxycheq El Cheapo II kit and after opening it up, noticed that the resistor was missing.

Included in the kit is supposed to be a .5 watt 300 ohm resistor. Figuring it was no biggie, resistors are inexpensive, I checked Radio Shack. They have .5 watt resistors in 270 ohm and 330 ohm, but no 300. Having a very limited knowledge of electronics, I'm not sure if either of these will work in place of a 300 ohm.

Will a 270 or 330 ohm resistor work instead of a 300?

Thanks

Brian

wingnut:

I just got an Oxycheq El Cheapo II kit and after opening it up, noticed that the resistor was missing.

Included in the kit is supposed to be a .5 watt 300 ohm resistor. Figuring it was no biggie, resistors are inexpensive, I checked Radio Shack. They have .5 watt resistors in 270 ohm and 330 ohm, but no 300. Having a very limited knowledge of electronics, I'm not sure if either of these will work in place of a 300 ohm.

Will a 270 or 330 ohm resistor work instead of a 300?

Thanks

Brian

Click to expand...

Hi Brian,

I actually wound up replacing my resistor with a trimmer-potentiometer. This helped me fine tune the "range" of the meter when I was replacing oxygen sensors. My new sensor was off the scale with my original resistor. I used Radio Shack part number 271-343 which I found in stock locally.

Once your meter is working, put your large potentiometer in the middle of it's range, then adjust the timmer pot to 20.9%. This will help a lot as you use the analyzer in different temperatures, and make your life much simpler a few years from now when you change sensors.

Good Luck and Happy Birthday!

Drop them an email I'm sure they will send one out, asap.

The resistor is normally packaged with the short sections of wire and looks much like one. If it is missing I am sure they'd send one to you ASAP.

O2 sensors measure partial pressure not percentage, so calibration is dependent on barometric pressure. At higher altitudes and/or lower pressures, you tend to run toward the end of the range of the potentiometer even when adjusting the internal pot as well. If the resistor is not 300 ohm, I suspect it could cause you problems at one extreme or the other.

Thanks for all the help. I ended up using the potentiometer-trimmer as Scott suggested and it seems to work great...at least at sea level...

Thanks again,
Brian