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You're right, my mistake. Must have copy/pasted incorrectly when creating then file for the new version; you can just delete the first 28lines. I've updated the file in the tutorial, as well a copy here. Confirm your update above is correct, but just ensure the two #define lines are first before...

Hi Xtream, The resistor is only required if you need to increase the overall resistance of your wound copper wire. You really need to be able to measure its resistance before use - do you have a means of doing so with a multimeter or similar? If not, you might find it easier to use the off the...

Yes you're exactly right: applying a the electromagnet to your setup is more convoluted than it needs to be, which is why I suggested dropping the electromagnet, cutting your speed sensor and pushing the ardunio in the middle of it. Only go own the electromagnet route if either you don't want to...

Hi Tony, Yep I bet you could avoid cutting the speed sensor. You'd need to track down the same plug that the sensor uses to get into the motor and then just use that as you say to wire in the arduino. Not sure if maybe it's the same plug as aux power cable I used above? The aux cable goes into...

Hi guys, I think the easiest way to set this up would just be to cut the existing speed sensor cable between motor and wheel and insert the Arduino in the middle of it. From the wheel end, this would look exactly the same as the current setup as in the tutorial: reed switch on the wheel feeds an...

I was setting up a multiplier = 1.6 for a friend and encountered the behaviour. So if you're not having any trouble at 1.4 then I'd say just leave it, but just remember it's there if you need it in future.

That's excellent Sander. How did you finish up with the coil? What diameter, number of turns, resistance, position etc did you settle on? I'm still using the off the shelf magnet, but maybe I should move over as well.

Hi all, I've made a change to the code above, and updated the tutorial's code file accordingly. New version attached here too. I found that big multipliers didn't behave well around fast accelerations from stopped, or while traveling very slowly; up a technical climb for example. I've made a...

Thanks Stratosa. Bluetooth would add some complexity but certainly possible. Just remember you'll need some sort of controller, like the Arduino, to run the bluetooth receiver and the electromagnet at the motor end.

Great news Sander. Yes I got those same errors when setting up. Luckily they're just diagnostic errors rather than anything serious, restarting the system should clear it. The placement of the magnet is what does it. Just keep moving it around until it clears up. Or as you're going to, try...

Hi Sander, I used 0.25mm wire for magnet I wound. If you're on 5v and approx that diameter, you shouldn't need a resistor. Just add a few more turns if you find your resistance isn't there. But in this case, close enough is good enough, as you can always adjust the placement of the coil a...

Ahh good spotting - I've updated the text above!

Hi Sander, You'll need to power the device externally in order to give enough power to the electromagnet - USB won't deliver enough. Also, did you end up getting the 12v magnet? If so that could also be the trouble when attempting to power it from the 5v output. Let me know how you go?

Yes your wiring is correct. But at 80ohm, you might need a larger resistor: The 5v magnet is around 15ohms, giving 0.28A current draw = 1.39watts Your 12v magnet @ 80ohms will draw 0.15A = 1.8watts To achieve the same wattage, you'd need ~100ohms total, so a 20ohm resistor to be added. Though...

Yep you're right, but you'll probably just need to add a resistor to reduce the increased magnetic strength of the electromagnet (due to the extra voltage). It's easy to do if you need it; resistors are just added in line to the magnet. You'd probably need something like 10-20ohm resistor...

Apologies for the repost of some of this, but this single post can be a single point of reference for the rim magnet derestrict. My build is based on an Ardunio microcontroller, reed switch and electromagnet. I removed the bike's rim magnet and instead placed a traditional magnet on the disc...

Yes I'm sure the bosch sensor will work, but you'll probably wince a bit when you need to cut the plug off it in order to solder to the arduino! Having said that, it looks like the sensor in the motor which reads the rim magnet is not just a reed switch. Instead it seems to have a built in...

Thanks Sander. I'm not using Bosch's speed sensor, it's just a random waterproof reed switch ;) And yep exactly right, the magnet on the disc is just sitting there with... magnets!

I expect to receive the auxiliary power cable in the next couple of days. I'll put something together when it turns up!

Certainly is possible yes, but by essentially capping the top speed that the motor will see irrespective of an increase in cadence, for example, it's likely the manipulation would be detected... Maybe I'm giving Bosch too much credit, as that's what other derestrictors on the market do, but...