The last type of temp probe is the three-wire devices such as the LM35. Internally, these are similar to #2 above, however they require +5V and GND, and then output a voltage on their own, so they do not require a pullup. The LM35, as an example, is calibrated in degrees C rather than degrees K, at 10mv / degree, so that the output can be read directly on a cheap voltmeter (.50 volts = 50 degrees, 1.10 volts = 110 degrees, etc.
auraslip wrote:I'm still using the HK VT - http://www.hobbyking.com/hobbyking/stor ... oduct=9744
...I've found out that the sensor itself is a $1 LM35
auraslip wrote:Oh... I don't know. It may be a mistake on my part.
Joe Perez wrote:There are three other major types of temperature-sensing devices in common use, and I suspect that that you have one of them.
The first, which is the only device properly named a thermistor, is a variable resistor whose resistance changes with temperature, either increasing as temperture rises (PTC, or Positive Temperature Coefficient) or falling as temperature rises (NTC, or Negative Temperature Coefficient.) These devices have two wires, of which one is usually grounded and the other has a pullup voltage applied through a fixed resistance, thus forming a voltage-divider.
The second is essentially a zener diode whose reverse breakdown voltage changes with temperature. These are also two-wire devices, and are used in a similar manner to thermistors. An example of this would be the Texas Instruments LM335.
Finally, there's a class of devices which are internally similar to the above, but which contain active circuitry and output a positive voltage proportional to temperature. These are three-wire devices, and an example would be the TI LM35.
Beachcruzer wrote:Anybody hacked something like this for a motor temp probe? Looks like the business end is similar to Doctorbass's BBQ probe, with a display that's smaller and will read in full sun. Temp range is right too.
http://www.amazon.com/Taylor-9842-Comme ... y_hg_img_y