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About BrianZ

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  1. I built a circuit that lets you use a hobby RC unit with Power Functions a while back. I updated the H-bridge to the one LEGO uses from my first try at it, but I have not done a writeup on it yet. I was having inconsistent results with my surface mount soldering techniques when I put this project on the back burner. I need to get it finalized and written up. Here is the writeup for the V1 of this project though:
  2. I get my solder paste from Sparkfun, at $9 for more than I would ever use. A rework station might be nice though. My version 2 of my 2.4GHz Lego remote control receiver is giving me fits, as my first surface mount project. Too much paste, not enough, solder bridges, and whatnot. It's harder than I thought, but I think that I'll get better quickly. Brian Z
  3. What are you trying to do with it? I built one of these, but it's probably not the simplest possible way. Pulse width modulation is your friend here, if you are going to design a circuit for it. Brian Z
  4. H-S, The DRV8833 comes in two forms, the square one with pads on all 4 sides, and the one with pads on two sides. I used the one with pads on two sides, and I used solder paste and an electric skillet to solder it. I put a blob of solder on the thermal copper surface I made just below it, and it seemed to solder and dissipate heat just fine. I have had to re-work every single one of the ones I have made; apparently I am using too much solder paste. They all turned out fine with solder wick and an xacto knife in the end though. My point is that I have had to reheat every one of the DRV8833 chips, sometimes with the skillet and sometimes with my soldering iron, and they all survived. This is the first thing I ever soldered that was surface mount, so experience isn't critical, apparently. Pololu offers a DRV8833 board already soldered that I would like to try. It's small. I'm going to do a writeup on my updated system any day now. I'll post here when I have more information. Brian Z
  5. That is super impressive. I'm using a laminator with toner transfer to make double sided boards, but those vias on your board fill me with envy. That's just something you can't do with home-fabbing, and It makes my board quite a bit bigger than yours, even though it looks like I have fewer components. I can't put a via under a chip, because mine are a soldered wire going through the board, and it makes a lump. Again, impressive work, and I'm excited for you. I know how good this part of a project like that feels. Keep up the good work, and post a video of the final project. Brian Z
  6. As long as I'm flapping my yap about what I would like to see in Technic, it would be fun to see sets that are motorized walkers, and odd machinery that doesn't have a real-life counterpart. Like giant versions of Yoshihito Isogawa's simple machines, wheeled vehicles, and the other book, which I can't remember. Whimsical things. They probably wouldn't sell well though. It would be cool if they had a great general Technic techniques book, that taught a lot of principles about building with Technic, and sold all the parts with it so you could build the examples. Like what if you could buy Yoshihito Isogawa's books with all the parts included? Or better yet, Sariel's book The Unofficial LEGO Technic Builder's Guide. Man that would be sweet.
  7. Howdy! I love what you are doing. I recently built a 2.4GHz receiver for Power Functions. You can see my progress here. It has a simple housing that I made out of two plates and 6 2x2 panels. Well, the pictures on my blog are 2x3 panels, but I've gotten it to fit in 2x2 panels. You said earlier that you were having PCBs fabbed. Have you tried etching your own, and soldering with a hot electric skillet? I learned everything I know about etching and soldering SMD parts from working on this project. My new version is all surface mount, and is working awesome. I'm going to make a new blog post for the new version here in the next week or so. I hope you keep it up and find sweet glorious success! Brian Z
  8. I've only been on these forums for a little while, but the interests people have in Technics surprises me. Beforehand I assumed that people bought Technic sets pretty much exclusively for the parts. Maybe they built the set, but then they tore it down and built their own models, learning and exploring about mechanical engineering as they did so. This is what I would do if my kids didn't protect their instruction-built models so fiercely. In this way, I would run the Technic line as a parts bin, selling sets with liftarms, gears, pins, or whatever. This doesn't seem to be what the users of this forum (and probably the public in general) would like though. It's good for LEGO that I don't work for LEGO. Still, I wish I could buy a set of liftarms in a particular color, or a set of wheels.
  9. Use the Power Functions servo motor for the steering. It's pretty sweet.
  10. I recently built a radio controlled car with the medium motor and a servo, and it was ok, but the L motor was way better when I finally got one. The XL is even more powerful though, but quite a bit bigger. When you say competitive, what do you mean? I built my own circuit to use my LEGO motors with a hobby grade 2.4GHz radio system, and now I'll never go back to the infrared controls. I posted instructions to build it yourself at my blog, here. My son and I have been building and racing small LEGO cars all over the house, and it's the most fun I've ever had with LEGOs.
  11. That's really cool. I'm going to keep that in the back of my mind for future solutions.
  12. Man that's sweeet. Please update with a video when finished. What battery do you use with your system?
  13. Oh, Ok. I get it now. I was thinking controller=microcontroller in the housing of the thing that snaps to the motor, you were thinking controller=transmitter. Yeah, my transmitter has a return-to-center spring, but sometimes people will put a foam doughnut behind the wheel on the transmitter so that it does not return to center. What is your ideal wireless communication method between the transmitter and your model?
  14. I'm really surprised at how poorly the speed remote works. It doesn't seem like it would have been tough to make it return to center. Are there not more Lego car and truck builders than train folks? I ended up building my own system, and it works way better, for the same price as the IR system.
  15. Using a 555 is hardcore old school. There is no spring for return-to-center. The Lego servo uses a pulse width modulation signal on lines C1 and C2 (which is a high power signal, used to actually power the drive motors) to tell the servo where to go, and it uses the 0v and 9v lines to power the motor in the servo, via a control circuit. It's a wierd signal protocol because 0V on both C1 and C2 will not power a motor, but that's the signal to go to center for the servo. The output of your device must emulate that PWM protocol in order to control the motor. The device that hooks to the motor must have a vairable resistor that the microcontroller can read to tell it where it is, and use that information to calculate the difference between where the motor is and where it's supposed to be, and send an output signal accordingly. If you want to get into microcontrollers and you have no previous programming experience, let me suggest the Picaxe. It would make this project so, so easy. It is only a dollar or two more expensive than a 555 anyway. I will admit that the Picaxe has very little street cred though, certianly less than the 555.