? on Mr Hall Effect

[Albert Grippo]

  On Tue, 10 Nov 1998, Bruce Plecan wrote:
 
 > In the past, I done some trouble shooting with Hall Effect Devises.
 > Now, for the first time I hooked a meter to one with it sitting on the
 > table.  The one I'm starring at is a Toyota, it has a red lead, a white
 > lead, and a sheilded cable with ground.
 >   So being the Cone Shaped Hat Wearer that I am, I did the following.  Using
 > a 9v battery, I grounded it to the shell of the sensor
 > applied + to the read lead, grounded the meter (DVM on V),
 > hooked the meter's lead to the white wire, and then tested it.
 > The test being held a gm crank disc near the tip of the toyota
 > sensor.  The meter just flickers as I expose it to the metal?.
 > I thought it would open and close as the metal came close to it?,
 > yes/no?..


 I had the same problem - it has to do with the sensor being open
 drain. You have to put a resistor and possibly a cap in the circuit.
 When you do this, your DVM will stay at +9 while the tooth is far
 from the sensor, then drop to 0 when you bring it near.  I have
 the circuit at home and can post it tomorrow - it is very simple.

		-Al Grippo