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After I saw iron man, I immediately decided to tear some poo poo apart and mod it, and I just happened to have a broken power screwdriver that Mom gave me three days prior to tear up or fix. The rechargeable battery and the wiring/switch were good, so I figured the motor was burnt out. Solution: rewire the motor coils! Original shaft, stator, wiring, etc:  Whoops, no .5mm electromagnet wire lying around, guess I'll use my .4mm (26ga?) wire and give it a few more turns around the stator...  I put it back together and tried it out, but the power was really crappy -- more resistance in the coils, I'd reckon. The obvious solution was to hook it up to a power supply with twice the voltage of the factory NiCad cell. Rough math says about 3 amps through the motor at 6v.  And the final product: 
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May 18, 2008 09:37
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| # ¿ Apr 24, 2024 02:05 |
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Here's a couple custom electronics projects that basically worked, but didn't end up being usable: The IR Remote Repeater I have my stereo wired up with speakers in two rooms of my apartment, and since I moved in two years ago, I've been wanting to be able to use the stereo remote from my computer, which has no direct line of sight. I tried mirrors but couldn't get them reliably positioned, so my next thought was to make a repeater for the remote. TV/stereo/etc remotes operate by sending bursts of IR. Only IR modulated on a 10 kHz or whatever carrier pulse is recognized by the devices. The basic idea of the repeater is to grab the remote's signal with a demodulator chip, amplify it, and send the amped signal through a 555 timer to modulate it to the carrier frequency. I was building it on a breadboard a while back, but had to shelve it uncompleted to make space on my living room floor for other stuff. Some of the wires may be bent out of shape, but here it is:  And with a remote button being held down:  You can see the IR LED (grey) lighting up because digital cameras see invisible things. According to the oscilloscope I borrowed from the Engineering Department at school, everything was working perfectly. According to my TV and stereo, it didn't do poo poo. I suspect the power output to the IR LED isn't high enough, but I honestly don't know why it doesn't work. Oh well, it's still a snazzy little over-engineered IR-transmission detector. The clear (green) LED lights up when anyone uses a remote in the room. The Alarm Clock Stereo I am bad at waking up in the morning. I consistently turn the alarms off in my sleep. It usually takes me two or three alarms to become conscious enough to realize that turning them off is a poor decision. Yes, I have a "Clocky" alarm clock too (the one that rolls off your nightstand when it goes off). Here's my normal clock. Step 1 of the project was permanently disabling the snooze button, which has long been my nemesis.  I opted for a ridiculously overcomplicated solution to my morning issue: wire my alarm clock to the power switch on my stereo. I went into this one with no plan whatsoever. I ended up using the voltage drop between the ground/power traces on the clock's PCB as an indicator of when the alarm was going off. Apparently running the speaker pushes the internal power supply pretty hard. That voltage gets compared to a reference from a 9v and the comparator chip turns on a transistor which activates a relay, which is attached to wires soldered across the stereo's power button pcb mount.  It worked perfectly for about a week. As it turns out, the comparator's drain current is enough to bleed a 9v battery dry in about a month, and that changes the reference voltage for the comparator. It needs a fresh 9v battery to function and those get expensive. In retrospect, I should have figured out a way to get a stable reference voltage from the clock's circuits. Plus, this happened:  It's been a year and I've never gotten around to fixing/upgrading it. I'll see if I can find the pictures of the inside if anyone cares, but it's nothing too fancy. I'll post a couple projects that actually worked in a day or two.
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May 18, 2008 10:09
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This is my desktop computer case. The only hardware I've upgraded in 3 years is the video card, but I've been modding the case. First, here is the tower in normal operation and in "super-bright" mode. The four front LEDs were keeping me awake, so I wired a switch to turn them off. I also added a couple 12v fluorescent lights for the inside, which are easily bright enough to read by. In retrospect, they're overkill.  Here, you can see the light switch for the lights, and... INTERNAL SPEAKERS! I had a crappy pair of desk speakers lying around and decided to take them apart and integrate them into my case. The black toggle adjacent to the light switch controls whether the computer's audio goes to internal or external speakers.  Here's the board for the speakers' amps and such. Volume, treble, bass knobs which I don't touch anymore. The board is wrapped in an old antistatic bag (conductivity barrier), and placed inside the metal enclosure from a broken CD drive. The light/audio switches are directly in front of this.  And here's the power supply for the speakers -- it's a 12v transformer screwed directly to the computer power supply, with wires soldered to the 120vac points inside. 
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May 21, 2008 05:05
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eddiewalker posted:I'm sure I've told you this before, but you sure have a knack for making things more complicated than they need to be. touche.
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May 26, 2008 04:58
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Use a true-rms ammeter to measure the current going to the battery, if you have one. Alternatively, I think you can measure the diameter and rotation rate, find the tip speed from that, and compare those values to the wind speed -- there's a formula somewhere that'll give you an approximate power output. If you know the capacity of your battery, charging time will tell you quite a bit too.
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Aug 9, 2008 04:05
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