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looking for thoughts on a modification i want to try...

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    looking for thoughts on a modification i want to try...

    ok, so apologies if this is hard to understand as i am not that great at explaining half-realized ideas. i also apologize for being a "plz bro" by asking for help when i should do this myself.
    for legal/safety reasons in my area, i am wanting to add a brake light to an e-bike i am building with a bbs02/bbshd (not sure which yet but i dont think it will matter here) and i am planning to modify a very bright tail light, with its own power source, to use a bafang brake sensor as the "switch" to engage it. i have some knowledge on circuitry but to be honest the wiring diagram i need to draw for getting this idea to work is eluding me right now for some reason.
    i am wanting to rig the light to turn on when the motor cuts out and turn off when the motor comes back on. the brake sensor will not power the tail light, only act as a momentary switch to complete the circuit for the light. i just for the life of me cannot remember how to do that (been a long time since i took classes in electronic circuits) and cannot remember what that type of circuit is called i know it has to use a relay of some sort.
    so in summary i need to have an independently powered light to be triggered, not powered, by the same switch as the motor e-brake cutoff without causing any interference with the motor itself and cannot remember what type of circuit i need to make to do that.
    does this make sense?
    or should i just get a window/door alarm reed switch and ziptie it under the brake lever to use the magnet? thats option 2 since it clutters up the bars and they are delicate so it ends up being just one more thing to potentially fail.

    #2
    I don't know the name of the circuit and had a similar idea while back wanting to add a brake light. I ended up going with a CMeilan X5 w/ the brake option. the remote triggers turn signals and senses when you are slowing down and automatically triggers the brake light. It also has lane markers and recharges with a USB cord. the remote uses a CR2032 and they are easily removed when you are locking up your bike. Sells for under 35 bucks.
    2018 Motobecane Boris Fat Bike BBSHD Build

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      #3
      What is the brake light's independent voltage, and how many amps does it take?
      See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

      Comment


        #4
        Originally posted by pure_mahem View Post
        I don't know the name of the circuit and had a similar idea while back wanting to add a brake light. I ended up going with a CMeilan X5 w/ the brake option. the remote triggers turn signals and senses when you are slowing down and automatically triggers the brake light. It also has lane markers and recharges with a USB cord. the remote uses a CR2032 and they are easily removed when you are locking up your bike. Sells for under 35 bucks.
        thank you. i was thinking of getting a premade brake light but i dont trust the automatic sensor ones. they use accelerometers, and i dont trust the durability of those on a bike especially a hardtail. i prefer a semi-manual switch. even a pressure or toggle switch actuated by the brake lever would be good. cant use what i used to, 2 exposed wires to make a contact when the lever is pulled. wont work now since i have hydros.
        plus i am a tinkerer. i love to tinker and this is basically a toy i will eventually be able to play with so to speak. i used to know how to do this... but the ol' memory bank has been a bit fuzzy since last time i was run off the road by a road-raging ass-pirate of a driver when riding a 50cc, safely i might add, after i moved to maine. my head hit the pavement hard enough that my D.O.T. highway certified motorcycle helmet cracked a good one. my eggs are a bit scrambled from that as well as a few previous incidents i outlined in the i dont share my road thread in commuting. i am improving again, finally, but it is a long process.

        some days i still have difficulty thinking straight and there is a slight, albeit intermittent, loss of dexterity in my hands, and speech. picked up a few muscle tics and problems with my back got worse from it too. typing and cycling make a good physical therapy combo for those issues though so i will be ok if dont get hit again. brake light is a good way to avoid some of the morons who dont know what hand signals are. i am also going to wire up 4 motorcycle turn signals to a 3 way toggle switch and an led flasher relay powered by a 12v battery and mount them to my bike. might help a bit. i am also going to get an action cam to have proof of fault if i get hit again (knock on wood that i wont)

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          #5
          Originally posted by Tommycat View Post
          What is the brake light's independent voltage, and how many amps does it take?
          should be...2 or 3 AA or AAA batteries so 3-4.5volts at i think ... between 50 to 100mA if my math is right depending on what light i get. gonna mod a regular led tail light to remove flasher function

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            #6
            Looking for both brakes to operate light? And do I follow you by thinking that your adding a Bafang brake sensor kit to your hydros?
            See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

            Comment


              #7
              Originally posted by Tommycat View Post
              Looking for both brakes to operate light? And do I follow you by thinking that your adding a Bafang brake sensor kit to your hydros?
              doesnt have to be both brakes. can make due with just the rear, and yes i will be using the hydro sensor kit

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                #8
                The Bafang brake reed switches make between pins 4 and 8 (brake signal and ground) with the magnet removed. Shorting the signal to ground, pulling it low. Actuating the controller's motor cut-out circuit. The 5vdc is not used.



                See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

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                  #9
                  i have looked at this before (thanks anyway, by the way) and didnt see anything relevant to my idea. i may just have to get a second reed switch and zip tie it to the bars to use the same magnet, or something

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                    #10
                    Yep, had the same thought, as getting into the wiring harness, adding electronic components and a mini relay would be quite an effort for the results. (yet very slick and neat) One other possibility is perhaps using a pressure switch on the hydraulic line.
                    See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

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                      #11
                      true, though i am not sure what you are getting with "pressure switch on the hydraulic line" as the line does not physically move. might just be having a brain fart on that though. could you please lend a machete to my intellectual thicket here?

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                        #12
                        Was referring to something like this, though less expensive types might be used... Goes in the actual pressurizing fluid stream closing on pressure rise.

                        http://www.ebay.com/itm/Magura-E-Bik...wAAOSwlt9cNAcW
                        See my completed Magic Pie V5 rear hub motor E-Bike build HERE.

                        Comment


                        • pure_mahem
                          pure_mahem commented
                          Editing a comment
                          Interesting!

                        #13
                        Originally posted by Tommycat View Post
                        Was referring to something like this, though less expensive types might be used... Goes in the actual pressurizing fluid stream closing on pressure rise.

                        http://www.ebay.com/itm/Magura-E-Bik...wAAOSwlt9cNAcW
                        ...i never knew those existed. cool!
                        an idea i woke up with (yes i actually dream about tinkering sometimes) is to try to take the guts of a tactical flashlight pressure switch, like this: https://www.amazon.com/Pressure-Swit...ressure+switch
                        and extend the wire to the rear light and attach the pressure pad to the brake lever with some epoxy or something, so that i press it when i apply pressure to the brakes.

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                          #14
                          I think the simplest and lowest cost would be to put a small relay, 5V coil, from the brake signal to +5V and then use the contacts to turn the light on...

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                            #15
                            Originally posted by AZguy View Post
                            I think the simplest and lowest cost would be to put a small relay, 5V coil, from the brake signal to +5V and then use the contacts to turn the light on...
                            something like this? https://components101.com/5v-relay-p...king-datasheet
                            might be better than my idea for using a tactical flashlight pressure switch

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