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Using Reed Switches For E-Brakes

Posted: Jul 26 2009 2:34pm
by rkosiorek
this article gives an example of how to use a Reed Switch and a magnet mounted to the Brake lever to activate the E-Brake function of almost any controller. in my case i used the connectors for the Crystalyte controller. exactly the same connector is used on the Cyclone and Wilderness energy kits with exactly the same connections. the basic idea can be adapted to almost anything.

most controllers use a common theme for the E-Brake Line. to activate the E-Brake you short the E-Brake wire to GND or 0V. so the issue is really what is the easiest method to do that using a Reed Switch and a Magnet.

it is easiest if you use a Normally Closed Reed switch. AKA Form "B" contacts. i could not find any in stock anywhere. instead i found ones that were SPDT (both NO and NC contacts) AKA Form "C". wires were soldered on and the switches were sealed inside some thinwall 1/4" dia plastic tubes. i just sealed the ends with hotmelt glue:
reed switch.jpg
This ia a SPDT reed switch that is encapsulated in an hot melt filled plastic case.
reed switch.jpg (88.78 KiB) Viewed 9986 times

Brown = common
Black = N/O
Blue = N/C

you want the NC contacts because the brake function is activated when the input gets shorted to GND. the switch is mounted to the frame of the brake lever. the magnet is mounted to the moving part of the lever. when relaxed the magnet is close to the switch holding the reed open. when pulled the magnet moves away from the switch and the NC contact will short the signal to GND.

to use the most commonly available NO reed switches AKA Form "A" you need to find some mounting where the magnet moves closer to the switch as the lever is activated. easiest place to arrange that would be to mount the magnet to the cantilever arm at the sheath covered end of the brake cable and the switch to the cable between the arms. when you activate the lever, that piece of cable shortens pulling the cantilevers together, moving the magnet closer to the NO switch and activating it.
For direct connection to either Crystalyte or Cyclone controllers the Black lead and Pin 1 are not used. do not connect the black lead.
e-brake.jpg (98.52 KiB) Viewed 9987 times

Pin1 = not connected = V+ (on controller)
Pin2 = Brown = GND (on controller)
Pin3 = Blue = Input (on controller}

these connectors are the XS Series connectors from JST Manufacturing. they are used on the Crystalyte, Cyclone and Wilderness Energy motors. they are a very common wire to wire style connector.

to mount my ruggedised reed switches i found some rubber molding the cross section being shaped like the letter "P". the open end has a hole just under 1/4" diameter. the switch is a tight slip fit into that hole i glued the rubber to the frame of the levers. then i glued a round magnet to the lever itself. being a slip fit i can adjust the activation point by sliding the switch inside the rubber mount. friction will hold it in place. the rubber molding was originally used as a door seal for a small portable fridge.
short magnet rod mounted using a smaller piece of the same rubber molding
shimano.jpg (79.3 KiB) Viewed 9967 times
shimano2.jpg (88.39 KiB) Viewed 9984 times
variation using a disk magnet
generic.jpg (137.35 KiB) Viewed 9986 times

Re: Using Reed Switches For E-Brakes

Posted: Mar 14 2010 10:58pm
by rkosiorek
rscamp wrote:Thanks to getting the idea from others here on the sphere, I recently wasted several hours experimenting with using reed switches to disable throttle on my trike. I ended up getting some small NO reed switches from DigiKey and making some small brackets and a lever arm out of aluminum to swing a small magnet toward/away from the switches to activate them. This seems to work very well with the Sturmey Archer drum brake setup.

Both the left and right sides are done the same way and the switches wired in parallel for a logical OR to disable the throttle on contact closure.

Here's a link to a short clip showing operation.

Maybe this will help someone else with a similar type of brakes or maybe someone has a better approach...
_DSC8079.jpg (17.83 KiB) Viewed 9227 times
originaly posted by "rscamp" in ... =2&t=16929


Re: Using Reed Switches For E-Brakes

Posted: Jun 10 2010 11:37am
by Kingfish
I came across this useful presentation last night when looking for a replacement switch.
How a reed switch works

~Enjoy, KF

Re: Using Reed Switches For E-Brakes

Posted: May 27 2013 7:18am
by spinningmagnets
Just consolidating several more reed-switch threads here, so all the links and helpful pics are in one place. Buried in these linked discussions are examples of using a hall-sensor for the switch, and also a mechanical micro-switch, all of which work fine.

"Shimano Deore XT brake lever switch with Hall effect sensor" (avandalen, 2 pages) ... =2&t=43680

"Normally Open Reed Switch as ebrake" (sunder, one page) ... =3&t=47423

"Reed Switch buggered" (Kingfish, one page) ... =2&t=18944

"How and where to mount magnetic reed switch for regen brake?" (electrobent, one page) ... =2&t=16722