Shop OBEX P1 Docs P2 Docs Learn Events
Looking for a sensor — Parallax Forums

Looking for a sensor

ArchiverArchiver Posts: 46,084
edited 2000-10-03 17:25 in General Discussion
Hi,

I'm trying to make a speedometer for a scooter and need to find a good
sensor to attach to the Stamp. The sensor will need to pick up to 20
revolutions of the wheel per second at full speed. The tires are solid
rubber so I can wedge something reflective or a magnet in its side. I was
looking through catalogues but only found light sensors and phototransistors
but from the specs I can't figure out how fast they are. Does anybody know
of a sensor that detects magnetism or metal? and are there other types of
sensors I could use?

Thanks in advance,
Alex

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 03:13
    Alex:
    Bicycle speedometers use a magnet on the wheel and a magnetic reed switch on
    the fork. Radio Shack has reed switches that may be sensitive enough. You
    will need to debounce the reed switch output.

    Ray McArthur

    > I'm trying to make a speedometer for a scooter and need to find a good
    > sensor to attach to the Stamp. The sensor will need to pick up to 20
    > revolutions of the wheel per second at full speed. The tires are solid
    > rubber so I can wedge something reflective or a magnet in its side. I was
    > looking through catalogues but only found light sensors and
    phototransistors
    > but from the specs I can't figure out how fast they are. Does anybody
    know
    > of a sensor that detects magnetism or metal? and are there other types of
    > sensors I could use?
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 03:13
    Alex,
    You could use a reed switch if the clearances are small enough. reed
    switches are switches triggered by magnetic current. As the magnetic field
    goes by, the reed switch turns on. Bill
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 03:17
    Alex:
    PS to my last post:

    20 closures per sec may be pushing the speed of a reed switch... they are
    cheap enough to buy and test. If they are too slow, consider a Hall-effect
    IC.

    Ray McArthur

    > I'm trying to make a speedometer for a scooter and need to find a good
    > sensor to attach to the Stamp. The sensor will need to pick up to 20
    > revolutions of the wheel per second at full speed. The tires are solid
    > rubber so I can wedge something reflective or a magnet in its side. I was
    > looking through catalogues but only found light sensors and
    phototransistors
    > but from the specs I can't figure out how fast they are. Does anybody
    know
    > of a sensor that detects magnetism or metal? and are there other types of
    > sensors I could use?
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 03:20
    Try looking at Hall effect transistors..they are used in car's distributors
    if I recall right. Just have the magnet pass thru it to get a pulse

    Jay
    Original Message
    From: Alejandro Fubini <alex@f...>
    To: <basicstamps@egroups.com>
    Sent: Monday, October 02, 2000 6:36 PM
    Subject: [noparse][[/noparse]basicstamps] Looking for a sensor


    > Hi,
    >
    > I'm trying to make a speedometer for a scooter and need to find a good
    > sensor to attach to the Stamp. The sensor will need to pick up to 20
    > revolutions of the wheel per second at full speed. The tires are solid
    > rubber so I can wedge something reflective or a magnet in its side. I was
    > looking through catalogues but only found light sensors and
    phototransistors
    > but from the specs I can't figure out how fast they are. Does anybody
    know
    > of a sensor that detects magnetism or metal? and are there other types of
    > sensors I could use?
    >
    > Thanks in advance,
    > Alex
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 16:50
    Thanks,

    I think I'll try a hall effect transistor. It looks as though the reed
    relays are larger and slower than the transistors.

    Thanks for all your help.

    Alex
    Original Message
    From: Jay Kay [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=R8lawAbVAT7SEGGN6uWckgsW3LzIP1MeXRH9PTxTKBPLgUvvJWA9pZGA_UyvPGd3mngq3iUFMsznLVUV]pcb4u@e...[/url
    Sent: Monday, October 02, 2000 10:21 PM
    To: basicstamps@egroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] Looking for a sensor


    Try looking at Hall effect transistors..they are used in car's distributors
    if I recall right. Just have the magnet pass thru it to get a pulse

    Jay
    Original Message
    From: Alejandro Fubini <alex@f...>
    To: <basicstamps@egroups.com>
    Sent: Monday, October 02, 2000 6:36 PM
    Subject: [noparse][[/noparse]basicstamps] Looking for a sensor


    > Hi,
    >
    > I'm trying to make a speedometer for a scooter and need to find a good
    > sensor to attach to the Stamp. The sensor will need to pick up to 20
    > revolutions of the wheel per second at full speed. The tires are solid
    > rubber so I can wedge something reflective or a magnet in its side. I was
    > looking through catalogues but only found light sensors and
    phototransistors
    > but from the specs I can't figure out how fast they are. Does anybody
    know
    > of a sensor that detects magnetism or metal? and are there other types of
    > sensors I could use?
    >
    > Thanks in advance,
    > Alex
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-03 17:25
    There was a thread on this in the archives dealing with a bicycle.
    Original Message
    From: Alejandro Fubini [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Dg9TVN2pA96b0RnLRiSKB7_jJCteTRaSiLp_XN1kIaV0TBu0xH6PfeOTOEsYR2ZC853122_Zot0gGHH8zqV-o1BD]alex@f...[/url
    Sent: Tuesday, October 03, 2000 10:50 AM
    To: basicstamps@egroups.com
    Subject: RE: [noparse][[/noparse]basicstamps] Looking for a sensor


    Thanks,

    I think I'll try a hall effect transistor. It looks as though the reed
    relays are larger and slower than the transistors.

    Thanks for all your help.

    Alex
    Original Message
    From: Jay Kay [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=w6T3eA1fkoEVtJfxK9rdocNgnUT3qY10cbaGv7C_facmx4FP8-U6VjqdEurSPhWnyPAMRqGCkGHTU81O]pcb4u@e...[/url
    Sent: Monday, October 02, 2000 10:21 PM
    To: basicstamps@egroups.com
    Subject: Re: [noparse][[/noparse]basicstamps] Looking for a sensor


    Try looking at Hall effect transistors..they are used in car's distributors
    if I recall right. Just have the magnet pass thru it to get a pulse

    Jay
    Original Message
    From: Alejandro Fubini <alex@f...>
    To: <basicstamps@egroups.com>
    Sent: Monday, October 02, 2000 6:36 PM
    Subject: [noparse][[/noparse]basicstamps] Looking for a sensor


    > Hi,
    >
    > I'm trying to make a speedometer for a scooter and need to find a good
    > sensor to attach to the Stamp. The sensor will need to pick up to 20
    > revolutions of the wheel per second at full speed. The tires are solid
    > rubber so I can wedge something reflective or a magnet in its side. I was
    > looking through catalogues but only found light sensors and
    phototransistors
    > but from the specs I can't figure out how fast they are. Does anybody
    know
    > of a sensor that detects magnetism or metal? and are there other types of
    > sensors I could use?
    >
    > Thanks in advance,
    > Alex
    >
    >
    >
    >
    >
Sign In or Register to comment.