Not sure what I need, but simple for most of you

Discussion in 'The Projects Forum' started by pablo66, Feb 24, 2014.

  1. pablo66

    Thread Starter New Member

    Feb 24, 2014
    Hi first let me start by saying thank you in advance to anyone willing to point me in the right direction, for something that I'm sure is way too basic for all of you.

    I'm not sure what I'm looking for, but if I describe what I want to do, I'm sure there will be some simple solutions. I only have a very basic knowledge of how all this works, so please bear with me.

    I'm playing with some older electronic bicycle shifters. Basically there are two buttons and 3 wires. One power wire and one wire hooked to each of the two buttons. When a button is pushed the power wire is connected to the wire on that button and the bike shifts in one direction, when the other button is pushed it connects to the other wire and shifts in the other direction. I've used a piece of wire to bypass the button and confirm that it works just by manually connecting the power wire to each of the buttons.

    What I'd like to do is remove the buttons I currently have and replace them with some that are wireless. I know I need a transmitter and receiver, but am not sure what. Small is ideal.

    I'm not sure if I'm leaving out any info, but the system runs on a 7.4v, 3.7Wh battery. The transmitter would obviously need it's own battery, coin sized and my thought is that it might be easier if the receiver also runs on it's own coin sized battery so that I don't have to figure out how to get power for it to run.

    I guess the simple answer is that I basically need a way to wirelessly operate a switch with 3 positions.

    Sorry if this doesn't make sense, but if anyone has any suggestions, I would greatly appreciate it.

    Thank you.
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    There are a bunch of "wireless relay keyfob" type devices on ebay.. They will work just fine.
    on ebay try "wireless relay fob" and wireless relay fob 2 channel"
    Thats what you want.. Each relays job will be to act as that wire you used to bypass the switch..
  3. inwo

    Well-Known Member

    Nov 7, 2013
  4. inwo

    Well-Known Member

    Nov 7, 2013
    Yes, mine have a 7805 on board.

    That means the 12V boards may work on 7.4 volts.

    The 12V relays may not pull in but they are driven with discrete open collector BJTs.

    What that means is, the relays may not be needed for your app.

    That would save power too.:)

    Mine are a couple years old. Things may have changed.

    Close-up from link shows the 7805 but not the drivers. Could be they just went to surface mount components.
  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
    Unless you have some kind of physical disability or perhaps you are just looking to repurpose, I would not even bother with the electric shifters. Nothing but more to go wrong .

    Shimano tried this a year or two ago and it was a dismal failure. No one wants to be out on a ride and have their shifter fail on them because of a bad battery. And you are adding even more complexity to the mix.

    The tried and true cable shifting system is the best. Those that need a high degree of reliability will opt for friction shifting over index shifting or at least a shifter that can be switched from index to friction.