Anyone have details on how the Avocet 30 cyclocomputer magnet ring works?

[robot.hebobo]

Impressed with your ingenuity there! Well done you.
However, from experience, we used to sell these BITD and sold loads... They look great, but I seriously think every one came back after some use. I had probably three myself as they looked great, but each one packed up in a similar fashion to what you describe. I wouldn't expend too much time or effort. There is a reason they aren't hot on the second hand market, they're all dead.

Interesting (and disappointing) to hear. There was a time when these were everywhere though, so they're kind of iconic (at least to me) and I always wanted one. My old Specialized SpeedZone from the same era is still going strong - I think that was made in Japan by Cateye though, unlike the US made Avocet. Really was better quality, I guess!

I suppose I'll just leave it on the handlebars in clock mode so I can look at it, and imagine how fast I'm going

 

[robot.hebobo]

Final attempt, with new magnet orientation. Absolutely no difference.

I'm coming to the conclusion that the problem was never the magnet ring, but the computer itself.

Calibration doesn't help either, as the range of available wheel diameters is pretty narrow.

 

[Woz]

Hah, that's how I got this one (well, I offered $5 to take it off a bike at a garage sale, and the seller accepted)

I've now spent $12 on batteries, $18 on the magnetic field film, and several hours on CAD and 3D printing

It's a hobby, I tell myself.

Very very fair enough. It's all for love and not for love of the wallet in this weird environment. Sometimes. Obviously.

Good on you for sharing your exploits as these will get rarer.

Good on you if you can get the blessed thing to make any sense.

Had an early version back in the day as a teen, que Greg Lemond's fault. All I wanted to do with it was go over the 61 mph limit.

 

[bikeworkshop]

Do the magnets actuate a mechanical switch like the standard cateye, or are they cleverer than that?
Just wondering if the sensor/ switch is at fault rather than the magnets.

 

[robot.hebobo]

My understanding is that there are no moving parts. The sensor is a coil of wire that passes through the changing magnetic field from the excitor ring, which generates a changing electric current in the coil, and this is what the computer detects and figures out your speed from.

Seems overly complicated compared to the reed switch and single magnet everyone else used, but it was engineered and made in Silicon Valley! I wonder if they thought a reed switch, which is a moving part, might be susceptible to vibration induced false readings? It was one of the first electronic cyclocomputers so they were just figuring things out.