Hackaday Links: November 17, 2013

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If you purchased a knock-off FM transmitter and were unhappy with its broadcast range [Thiagohersan] shows how to double the range with a simple transistor amplifier circuit. He also hacked it for used without the 12V car socket.

[Patrick Herd] had a project that required him to strip about twenty Mindstorm batteries from their plastic enclosures. It’s not too tough getting into them but it does require drilling out the plastic rivets. He made a jig and used a CNC mill to automate the process.

Speaking of CNC, [Bertho] added some abstraction to distance himself from what he calls the “50+ years archaic syntax and grammar that G-code programs have”. The project is a meta-compiler for G-Code.

If you need a cold one and don’t have a HaDuino on hand you’ll thank yourself for hacking together this five-cent workbench bottle opener.

Just make sure you do all the lathe work for a custom speaker enclosure before you start pounding back those brewskis. Not only does [Shaun's] creation look modern and stylish, but it boasts more than enough power to bump some tunes.

Here’s a project that adds LED feedback to your XBMC installation. It uses a Raspberry Pi to run the media center software, and a script to monitor it and actuate the lights on an Adafruit add-on board. At first glance you may not think much of it, but this is all the logic control you need to automate your viewing room. Who doesn’t want a home theater that automatically dims once you’ve made your viewing selection?

And finally, [08milluz] snagged some reactive electronics in the form of Disney’s Mickey Mouse ears. Apparently they glow different colors at live shows and based on where they are worn within the park. He did a complete teardown to show off the hardware within. It turns out to be controlled by an MSP430 which are known for their low power consumption. [Thanks Spikeo55]

Comments

  1. tekkieneet says:

    The FM RF amplifier circuit has a mistake in it. There is a 10nF cap
    connected to ground from the collector node to the antenna. A 10nF cap
    has an impedance of 0.159 ohms at 100MHz.

    More than likely the 22pF and the 10nF cap values were swapped.

  2. Rich Grise says:

    I’ve been out of the loop for decades. Does the FCC still dictate limits on ERP?

  3. Bill Stewart says:

    The FM transmitter needs one other thing, which this hack doesn’t provide – an unused FM radio channel. As far as I can tell, we don’t have any of those in the San Francisco Bay Area (based on trying to use one in my car a few years back.)

  4. Chris C. says:

    My cheap FM transmitter was barely picked up even if I held it against the receiver antenna. I looked up the chip and found that its RF Out pin was connected to some parts on the PCB that were severely reducing power. It seemed to be a deliberate and overzealous crippling of the device. Lifting this pin from the PCB and connecting a few inches of wire to it produced massive improvement, more than a similar single-transistor amp did. A proper antenna would have worked better, and addition of the amp even more; though in my case the mod alone was more than enough. It may not be possible to do this with all transmitters, but it’s worth checking into first.

  5. Hirudinea says:

    Re: Five Cent Bottle Opener – I gotta put about a dozen of these on my deck!

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