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Defcon 23 Shoot Electronic Badge

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  • #16
    Wow that's looking awesome!


    • #17
      Looking great! our group would buy some (3-4).

      Just my 2 cents if it gets too close to crunch time.. we could always go Analog this year with customized dog tags. Even have different colored ones for the range safety guys.


      • #18
        I liked the idea of AR500 steel hanging off your neck. Especially walking around with it after having it shot.

        We might be able to get this or something similar for around $5 if we ordered 100 of them

        Just make sure you use a 1" or thicker lanyard


        • #19
          Originally posted by seeess View Post
          I wanted to add more features to make it useful outside of the shoot (for when you're sitting in a boring talk or even after defcon), so I added some more features.

          Second video here

          There's other changes, mic thresholds are set in steps of 40 to give more control, you can press and hold to change certain values quicker, and probably other things I forgot about. No hardware changes just more code. Debugging the morse code mode was a pain in the ass not knowing morse code. But I plan on hooking that up to my xmas tree lights or something.
          For the temp sensor, I did try reading the voltage first and using that in the formula so the temp wouldn't drop as the batt voltage drops, It didn't work for me. Maybe I'll look into it again before defcon.

          I found a few friends that do schematics, and they know someone they hope to talk into doing a layout. Still moving forward slowly. I give the chance of success around 60-70%, if you can help with board design/manufacture let me know.

          I've failed finding any sponsors which kinda sucks, but at this point I have to start working on getting the board made so I'm not rushing last minute. If you know of any sponsors that might be interested PM me.

          Also I'll include a badge contest with the prize being around half a bitcoin (so the first people to get to the public key can claim it)
          Seeess, do you have any kind of voltage regulator in your circuit? What temperature sensor are you using? If you have/add a voltage regulator and run your temp sensor through it you should see more stable readings over the life of the batteries.



          • #20
            Originally posted by L0g1c10101 View Post

            Seeess, do you have any kind of voltage regulator in your circuit? What temperature sensor are you using? If you have/add a voltage regulator and run your temp sensor through it you should see more stable readings over the life of the batteries.

            No voltage regulator, I wanted to cut out all possible costs, plus I'd have to step down to ~4.5v from some higher voltage = more batteries. Also that would probably hurt the efficiency.
            I'm just using the internal temperature indicator (again, cost reasons)
            Yep a voltage regulator would help, but I don't even have a diode or any other common things you should add to a circuit.

            I mainly played with it because it was already built in to the microcontroller and free. If it was an external temperature sensor that I was paying for, I'd care more about making it work a little better.
            Same reason I built in the battery voltage readout, It was free by using FVR and the ADC intelligently so why not?
            I was basically running out of features to add, without adding hardware.


            • #21
              Your PIC claims to run off of anywhere between 2.3 V ~ 5.5 V and with 3 AAA (Alkaline or Zinc-carbon) batteries you would have ~ 4.5v (see here:

              This would remove the need for having and updating your voltage/temp offsets and would only require a single 3 leg component.

              Last edited by L0g1c10101; April 16, 2015, 12:24. Reason: Fix formatting


              • #22
                One other thing to keep in mind is the minimum input voltage. You wouldn't want a DC to DC output of 4.5v with a minimum of ~4v. since batteries pretty quickly fall to ~1.2v in their life cycle. But I don't think this will be a problem, most support a low enough voltage.

                There's still plenty of headroom to bring the output down to 3v.
                Thinking of other benefits, this would keep the LED brightness more static, and if i wanted to redo my mic circuit I may be able to save a resistor or two (that part is probably not worth it).

                Thanks for the suggestion, would you recommend a specific part? Here's what I found with a brief search:
                100 units of those would cost $1.58 each though, that's more than I was spending on the microcontroller. On the plus side the efficiency is much better than I was expecting @ 95%

                Edit: I'm being dumb, if you supply a DC to DC with less voltage than the output you need a boost converter == $$$$. So you'd want to run the chip close to 2.5-3v where the batteries would be toast anyway under your DC to DC output voltage.

                I'm not sure this is worth the cost though since it would "fix" the temp sensor, but you'd no longer have a working battery voltage.
                Pros: [1] Constant LED brightness (I can probably achieve close to this within 4.8-3.3v, worse case is you swap batteries a little earlier than needed), [2] temp sensor sucks a little less (still need to calibrate it, but only once)
                Cons: [1] batt voltage readout won't work anymore (no extra pin, i was using FVR), [2] cost of DC to DC and external components probably close to $1.80-2 (super expensive in comparison to other parts), [3] efficiency of DC to DC is 90-95% (batts die slightly faster)

                I think instead I'll re-look at reading voltage prior to reading temp (using the voltage reading to auto-offset the temp), to see if I can use that value correctly. I had some trouble initially, but hopefully I was just doing something stupid.
                Last edited by seeess; April 16, 2015, 14:50.


                • #23
                  It partly depends current/amp needs which I'm unaware what your currently using. As for that specific part.. $1.58 Yikes! I'd look for a 2.5v-3.0v fixed LDO voltage regulator or a Linear Voltage Regulator. These should function fine between 4.5v+ (3x AAA batteries at 100%) down to 3.6 or maybe even 3.3 (1.1v / AAA battery) if you use the 2.5v reg.

                  Depending on the current needed to run the LED's you should be able to find a part around $0.50 each when buying 100+.



                  • #24
                    This is absolutely awesome!

                    I've done board design, THT and SMD, and have buddies at a local fab shop that do all the supply and pick-and-place. They also pre-program all ICs before mount. Awesome place!

                    I use Fritzing for all of my work, very familiar with the tool and easy to use. Couple years back I did the BSides Orlando badge. Here are some videos of it:

                    You have an awesome concept proto here that has great functionality! I'm no dev, but I do enjoy EE and this is totally doable and I would so pay 15$ on top of my REG to get one of these.

                    If you need any help with getting in touch with a state-side fab shop, let me know. I can also do some basic layout if you need, if you can provide a schematic and BOM. SMD all the way.

                    ding me at


                    • #25
                      Just a small public note that I've committed to a small sponsorship to seeess from Ballistic Tools to help bring badge costs down.

                      BTW seeess LED perceived brightness isn't linear with current. It might not be as bad an issue as you might think.


                      • #26
                        Thanks for helping with sponsorship gigs. I got my first quote for the badges/population, and while the boards are only a little more than $1, the population/assembly brings the total manufacturing over $8 (not counting all of the components/shipping/lanyards/batts/displays/etc). This causes the total to push $20, and I was debating if i should only offer one set of batteries etc, so this will help me offer those extras without charging more than $20 (hopefully).

                        I did some more testing since my last post, since i've mainly focused on software for the last few months. The primary issue was the current sinking ability of the micro on the cathode side of the led display. As the voltage to the pic increases, so does the current sinking capability. All resistors are removed in the path of the display, and to have a bright enough display I really wanted to keep the voltage to the pic over 4-4.5v. 3AA's would do this right when you insert the batteries, but a few hours later the display would be dim. So the current plan is to go with 4 AA's, might be a little heavy but I tried to order a thicker lanyard to help with that.


                        • #27
                          put me down for one of these as well, if they make it to production.


                          • #28
                            I am totally into the badge...count me in for one!


                            • #29
                              As i've announced elsewhere, my first 8 volunteers to be on my staff will be given one of these for free. so sign up to help with the Shoot, people!

                              see more here...
                              "I'll admit I had an OiNK account and frequented it quite often… What made OiNK a great place was that it was like the world's greatest record store… iTunes kind of feels like Sam Goody to me. I don't feel cool when I go there. I'm tired of seeing John Mayer's face pop up. I feel like I'm being hustled when I visit there, and I don't think their product is that great. DRM, low bit rate, etc... OiNK it existed because it filled a void of what people want."
                              - Trent Reznor


                              • #30
                                Lanyards and displays in (easy parts). Now I just have to hope the boards end up working

                                Ohhhhh glow in the dark