Hackaday Links: November 10, 2011

Experimentations with haptics

[Chris] sent in two videos (1, 2) documenting his experiments with haptic feedback. He’s recording the position of a DC motor and can either play it back or send it to another motor. It’s very similar to the kissing robot we saw earlier this year, but we’re not making any judgments.

Mobile Emergency Repeater go bag

[Nick], a.k.a. [KF5JAK] sent in a few pics of his emergency/disaster relief amateur radio go bag. With a 3G connection via a cell phone, the MER can be used with EchoLink.

Launchpad MIDI booster pack

Earlier this month we lamented the dearth of add-ons for the TI Launchpad. The folks on the 43oh forums just came out with a MIDI booster pack. Time to dust off that old Radio Shack keyboard, we guess.

Macro photography with OH GOD WHARGARBL

You know camera lenses work both ways, right? [Karl] has been experimenting with this very idea by mounting a camera lens backwards and running a few wires so it’s electrically connected as well. Check out an example shot.

Keeping tabs on your kids’ homework

[Janis] doesn’t live with his kids but he wanted to keep track of their homework. He set up a document scanner that sends those worksheets straight to his email inbox. All he has to do is annotate them and send them back. This guy’s doing it right.

11 thoughts on “Hackaday Links: November 10, 2011

  1. Love the Echolink go-bag. I can see it being very useful in SAR efforts and emergencies that are not large scale. That being said, I don’t see it being very useful in a widespread emergency… It relies on cell phone towers being able to route the traffic to the internet. Those two technologies could easily be unavailable in the event of a flood, nuclear attack, zombie apocalypse, or similar event.

    If things go south, pure radio is where it’s at.


    1. Disclaimer: Yes, I did RTFA. I realize it’s primary purpose is an emergency repeater, which would in fact be very useful in the event of a widespead disaster. Just the Echolink portion probably would not be.

      1. Could use codec2, and some sort of transport/network protocol for that. Recently codec2 has had 2100bps and 1400bps candidates. Heck, at that rate you could shoot 2 or 3 streams down a 4800baud connection. Too bad NEO balloons are so short lived, a couple hours at most. I’ve seen a repeater based on two Baofeng UV-3R radios recently with a cheap duplexer from China. A crossband repeater with two radios and no duplexer would be really light. Could be hoisted up in a balloon probably. Maybe someone could make a DIY blimp with one to float over a disaster area to handle comms in and out. Maybe even better with a wifi mesh node to handle multiple channels of digital audio and other data.

  2. While the principle of the MER is good. The execution is pretty poor. The RX sensitivity of the scanner will be relatively low, any in-band TX with the two units that close together will result in some intermod back into the scanner. Also, the point of a repeater is to increase effective TX range of a low powered station. Using a low powered HT as the TX side of this repeater will not result in very good range, especially if they’re employing a standard rubber duck antenna as they seem to be.

    Not bashing on the concept or the construction. It’s a great idea and something I’ve worked on myself in the past but always with a higher powered mobile radio (25w at least) for the TX and utilizing at least a pair of external antennas.

    1. I understand those criticisms, and I don’t know what the author intends to do with it.. But if they intend to use it in an urban setting then maybe they can find a tall building and use a portable vertical antenna. You can get quite a far range. My first radio was an older HT with 5W out and a 2meter base antenna and that got me far for the first several years. A portable yagi could get even more range if you know the direction you want to talk.

      1. Yeah, 5w will get you a long way but it’s all terrain dependent. Like you said, a 2m base antenna or portable yagi would work well. Even some roll up J-pole antennas and some vertical separation would be a massive improvement.

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