I need a circuit that will sense the hall effect magnet

Yoshi

I am total newb to the basic stamp, and designing circuits.
I have a project I need to get done fast (really fast) and don't really have the time to learn everything to make it work right.
I will be experimenting and learning later but for now it just has to get done ASAP...

Its a pretty basic thing. I am good at building, so I just need a circuit that will work and hopefully some code suggestions.
Heres what I need.

I have hall effect sensor and magnets from parallax.

I need a circuit that will sense the hall effect magnet when it passes by the sensor and will simply activate a solid state relay for a defined amount of time each magnet passes the sensor.

It shouldn't effect the circuit, but to give an idea I have 30 magnets positioned on a rotating disc. I need it to signal the relay so it can fire a strobe at precisely the point the magnet is in front of the sensor (where someone will be viewing the animation). This is so it can freeze the motion of the rotating disc.


Thanks,
Yoshi

Post Edited By Moderator (Chris Savage (Parallax)) : 7/17/2007 2:38:47 AM GMT

PJAllen

· Hall Sensors turn on when their threshold is crossed, the magnet needn't be directly in front; magnets vary in gauss (Gs) and thresholds vary unit to unit, too.· So, this approach won't be as nip-and-tuck as you might figure.

· Anyway, the Hall sensor output could provide the trigger·to "one-shot" (based on a 74HC123 or 74HC221) and the one-shot output could trigger your "strobe."

· Was it your intention to use a Stamp?· Maybe this should have been posted over in The Sandbox.

Yoshi

yes it was my intension to use a stamp.
Because I might need to build in a delay which I could control with the stamp.

PJAllen

I don't know if your strobe triggers on a high or a low, likewise the state of the Hall.· You'll have to work that out yourself.· Here's a real quick-and-dirty program --

' {$STAMP BS2}
' {$PBASIC 2.5}
 
INPUT 0
OUTPUT 1
 
OUT1 = 0
 
trigger:
  IF IN0 = 0 THEN strobe   '0 on Input = Hall detect
  GOTO trigger
strobe:
  OUT1 = 1
  'use Pause for a delay
  OUT1 = 0
  GOTO trigger

You could use PULSOUT in the "strobe" sub-routine instead of OUT.· Any more than this from me and we're looking at design fees, N-R-E, etc.·

··