[arm-allstar] A simplified USB FOB modification

Doug Crompton doug at crompton.com
Thu Jun 25 09:04:15 EST 2015


Jim,

 I understand the desire to try to put all the parts on the board put that is often a recipe for disaster and so much harder for most people. Absolutely minimizing what you do to the board is the best approach. I have done it both ways and cutting things or de-soldering things often leads to problems so when I realized how easy it was to do it this way I wanted to share it.
73 Doug
WA3DSP
http://www.crompton.com/hamradio


Date: Wed, 24 Jun 2015 23:39:30 -0700
From: jim.pilgram at gmail.com
To: arm-allstar at hamvoip.org
Subject: Re: [arm-allstar] A simplified USB FOB modification

I've had better luck on the switches using a nipper and just simply cutting the 4 corners at the board. The less you have to put the soldering iron on the board, the less chance of lifting a trace. I also use the nippers to cut off all the jacks. All parts go on the board and a 5 conductor cable is fed out one of the jack holes in the case. I use super glue to weld the buttons on the cover in place and reuse them. ‎I've made about 25 of these to date for myself and our group. We are using primarily CDM series Motorola simplex nodes and I put them together including the motorola 20 pin connector for about $16.50 total price. I have them on 3 motorola MTR2000's and they work great. 
I don't think I'd personally  want to make a‎ career out of building these but it was fun for a while and I only messed up 3 of them and that was the pin 13 wire connect. Once I started putting hot melt glue on them, I quit breaking off the lead.Jim                                                                                                                                                                                                                                                                            Sent from my BlackBerry 10 smartphone on the Verizon Wireless 4G LTE network.                                                                                                                                                                                                                                         From: LarrySent: Wednesday, June 24, 2015 20:32To: ARM AllstarReply To: ARM AllstarSubject: Re: [arm-allstar] A simplified USB FOB modification

  
    
  
  
    Pictured in Doug's previous FOB
      article: 

      

      If you are squeamish about connecting to the CM-108 chip there
      really only needs to be a single wire added directly to the CM-108
      chip. That is PTT (pin 13).  COS (pin 48) is accessible on the
      left side (top or bottom solder joint) of SW1 (Vol DN). If you
      want/need more room to solder a wire take a needle and press it
      under each of the 4 corners of SW1 as you touch each corner with a
      soldering iron. The switch will lift right off and you will have
      the trace exposed under the left side of the button to make your
      connection to pin 48.

      

      CTCSS detect (pin 39) is available on the right side of SW2 (Vol
      UP). The same proceedure will work there if you want that signal.

      

      Larry - N7FM 

      

      

      On 06/24/2015 12:28 PM, Doug Crompton wrote:

    
    
      
      Well to answer your two points.  The
          link on the site for the FOB is not potted. It is the one
          shown in the photos. As far as soldering is concerned there
          are only two potentially tricky connections to the pins of the
          CM108 but as I pointed out if you use the right size wire and
          tack it on it is not a big deal. You might be surprised how
          easy it is. At $3 each sacrifice one to experiment and maybe
          it won't even be a sacrifice! The rest of the components you
          can mount or build anyway you desire. It is shown in a DB25
          shell but that is certainly not a requirement. At first I was
          going to put a little perf board in there but then realized
          that most of the components could be mounted right of the
          connector. 
        

        73 Doug

          WA3DSP

          http://www.crompton.com/hamradio

        

        

        
          Date: Wed, 24 Jun 2015 11:44:16 -0600

          From: mike at mtweb.net

          To: arm-allstar at hamvoip.org

          Subject: Re: [arm-allstar] A simplified USB FOB modification

          

          On 6/24/2015 3:42 AM, Corey
            Dean wrote:

          
          
            One of the Main reasons I was looking for this in acid
              and now the pi2 is due to the blob.  Some of us ordered a
              bunch just to find you could't get to the chip to modify
              it.

              

              Corey N3FE
            

              On Jun 24, 2015, at 2:11 AM, Doug Crompton <doug at crompton.com>

              wrote:

              

            
            
              
                
                I often get requests for
                    GPIO control of COS and PTT on the BBB and RPi2.
                    While we are going to have that capability in the
                    next release at least for the RPi2 I often wonder
                    why the great desire to do this and what the problem
                    is with just modifying the FOB. No matter where the
                    I/O control comes from you still have to build a
                    minimal interface for the signals. Having it all
                    come from one place, the FOB, has several
                    advantages. One is you can use the code as it is
                    now, the other is is you are not tying up I/O on the
                    main board and running wires from two different
                    places.

                    

                    In our testing I have built and tested it both ways
                    GPIO  from the RPi2 or the FOB and I honestly think
                    it is easier to just modify the FOB. I have written
                    an article showing an easy way to modify the FOB
                    that I think most hams who have soldering and small
                    construction experience could handle. It saves you
                    about $70/node to do this and a couple of hours of
                    your time. The article is in the how-to section at hamvoip.org 

                    

                    Here is a direct link to it -

                    

                     http://crompton.com/hamradio/usb_fob_simple_modification/

                  

                  So give
                    it a try. You certainly don't have much to lose at
                    about $3.50 in single quantities!

                  

                  I would be
                    glad to answer any questions you may have about this
                    project.

                  

                  73 Doug

                    WA3DSP

                    http://www.crompton.com/hamradio

                   
              
            
            
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          For me, it is my eye site, isn't as good as it use to be and
          everything has gotten way to small.

          Just finished up building a controller and had to use a 5x
          magnifier.  At least when you bread board stuff you can space
          things 2 microns further apart than half an atom:)

          I think most hams are older now.  I don't see the younger
          crowd getting in to the hobby, sad to say.  So size of stuff
          is more important to me now.  As I wont tackle a project that
          requires a lot of smt components.

          Mike

          

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