Reed switch theory

wrbix

wrbix

Pattern Altitude
Joined
Jul 25, 2013
Messages
2,398
Display Name
Display name:
Pilot Lite
Bear with me here:
I’ve a vintage cyclometer on my vintage road bicycle (Cat Eye Micro CC-6000, and Bob Jackson Super Tourist respectively, not that it matters). The cadence has stopped registering and via diagnostics with a magnet and various jumper wires, it appears the issue is the wired pickup sensor that senses a magnet on the crank (and, no it’s not just a placement issue).
The question before I invade the sealed sensor: I’m assuming the sensor is a simple magnetic triggered reed switch, but with only one small-gauge wire leading to it (and no connection to ground at the sensor) what signal and how is said signal sent to head unit? I’d think if the switch closes (or opens) a circuit there’d have to be two wires. There is no battery in the sensor.
I’m sure it’s something simple - the thing’s 30+ years old (a Second World Problem?)
I’m thinking I might could just replace with a generic reed switch but the circuitry confounds me (in its simplicity). Cat Eye support of no help - just want to sell me a new wireless model.
 
If it's a single wire the only thing that makes sense to me is there's a coil in the pickup, and as the magnet passed by it generates a pulse.
 
Bill Jennings said:
If it's a single wire the only thing that makes sense to me is there's a coil in the pickup, and as the magnet passed by it generates a pulse.
Click to expand...
Ah, hah - yeah, that does make sense. Thanks!
Knew the wealth of knowledge and experience here would come through!

....but, alas, sounds less likely to be an easy fix.
 
Hall effect switch.
 
George is right. Most of the cycle computers I had used hall effect sensors.
 
I have a Cateye wireless computer which, interestingly, will display 62 mph when positioned at the right point on a traffic sensor.
 
Just now (not last week) found two NOS CC-6000 Cateyes on the Bay. Ordered both - can’t have too much vintage stuff - not being made anymore....that’s why it’s vintage.
“Classic never goes out of style”....wouldn’t trade Bob for the latest/greatest/lightest modern bike.
 
Bill Jennings said:
Exactly, his says his sensor is a single lead.
Click to expand...
Which is impossible in any event barring using the bike frame for a ground (which he says isn't happening either) regardless of the technology. Some Cateyes are wireless (have a little battery in the sensor), but they have ZERO wires then.

All the Cateye ones I know of have reeds. The Garmins use hall effect.
 
flyingron said:
Which is impossible in any event barring using the bike frame for a ground (which he says isn't happening either) regardless of the technology. Some Cateyes are wireless (have a little battery in the sensor), but they have ZERO wires then.

All the Cateye ones I know of have reeds. The Garmins use hall effect.
Click to expand...

Probably even the wireless Cateyes, as there is an audible click when the sensor passes.
 
I assume you've looked at the connections at the other end... are you sure it's a single wire and not a very small coax?
 
Dana said:
I assume you've looked at the connections at the other end... are you sure it's a single wire and not a very small coax?
Click to expand...
Yeah, that thought’s been gnawing at me - haven’t cut a wire yet....but will when replacement arrives...standby for update.
 
You must log in or register to reply here.
Back
Top