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bobnova

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Everything posted by bobnova

  1. 24 years of auto repair. Same flyback issue, far larger coils and metal pistons. The solenoid inside the starter (or on the fender) does exactly the same thing the injectors do electrically (coil moving a metal slug), except with a few hundred amps. Similarely the starter is a massive load, when you suddenly cut a massive load you get a nice big spike. It's short, how short depends on the inductance of the wiring. In the starters case probably in the hundreds of nanoseconds at most. The solenoid's spike(s) are much longer.
  2. It's a transient from the motor coils getting suddenly cut off from power, plus another transient as the field inside the solenoid collapses and the solenoid piston snaps back into position. Alternators put out a fair bit of noise too. Neither is something you'll see without a scope though.
  3. If you're thinking resistors, don't forget that with the motor running you'll have more like 14v-14.7v at the "12v" battery posts. With the engine turned off and not being cranked, you should have 12-12.5v. Cranking it must stay over ~9v or the car will never start due to the electronic ignition parts needing 9v (ish) before they can function. If you use resistors, size them for 15v, they'll still be plenty bright at 12v when the engine is turned off. If you size for 9v and run at 14v, poof! EDIT: Also bear in mind that the "12v" has some pretty decent spikes in it, expect spikes of 17v
  4. I've used hot glue on a couple dozen video cards to hold voltmods in place. Only time I've had issues is when I killed the card and had to bake it back to life in the oven. Droops a bit, then Make sure you get it nice and hot, being impatient and applying before it's at full temp will result in a poor bond. Extreme cold can cause issues too, not recommended for devices exposed to liquid nitrogen (video cards again, for me), at least not on the cold bits.
  5. It doesn't match the Attiny series very well, VCC and GND are diagonal on the Attinys rather than both at one end. It (attinyizing) could be done with liberal trace cutting, though it'd be easier to use something that matched up better, or to simply have a floating brainboard that jumper wired to the original chip's pads. Or a MSP as said before. Programming an Attiny in place on that board with be a pain too, no single/double pin JTAG, it's ISP/ICSP or forget it. I'd guess it's probably either custom, or a couple comparitors.
  6. In my extremely limited time spent looking at EEPROMs, the larger the chip the more complicated the addressing seems to be. More pages (pages at all...) and so on. I haven't actually used any EEPROM other than the bits built into the Arduino though, and that was done with a library. The main things I suddenly need to have/use tend to be caps (I loot old PSUs. Hazardous occupation, that), inductors (PSUs again), logic level NPN and PNP MOSFETs of decent juicyness (digikey) and 555s (to drive PNP MOSFETs, or to drive non-logic level NPNs, or to generate frequency outputs), trimmers (voltmod
  7. Outputs do ring somewhat as far as I know / can tell. It's a function of the MOSFETs among other things. My analog scope shows ringing on MSP430 outputs as well as ATTINY85 and Atmega328 outputs. A resistor (100ohm) in line with whatever I'm switching removes it. I get extremely similar ringing on MOSFETs that are switched too hard, a resistor between gate pin and MCU gets rid of it. Jeelabs did a thing on it, too: http://jeelabs.org/2012/12/05/ringing-mosfets/
  8. I'd go easy on these things on USB ports. I measured my 60LED strip at a bit over 2 amps of 5v (with a cheap multimeter) with all 60 at 255. Some USB port fuses are that size or less, and are one-time fuses. Don't want to kill your USB ports! (USB2 ports are rated for 500ma. USB3 ports are rated at 1500ma) These are hungry little things. On the topic of another GB, I want two more meters, at least.
  9. The "BlinkWithoutDelay" example code that comes with energia (in the digital section) should get you going. It looks like that library might function in Energia if copied over. I didn't see any references to Arduino specific HW while glancing through it.
  10. How much modifying? If you're willing to do some creative modifactions to the feedback bits and replace all the capacitors on the second side you might be able to get a decent bit more. I don't know that anybody has tried. I seriously doubt you'd get 30+ volts though, the transformer is wound to take ~380v and make it 12v after all. The 12V filter caps are all rated at 16V, as such going over 13.5-14ish without replacing them isn't an especially good idea.
  11. I have two Launchpads, one BBB (Arduino cloneish), three RBBBs (smaller of the same), a Diovolino (only Arduino clone I have that accepts shields) two self-made Atmel Attiny85(and other 8DIP) dev boards, a basic-II stamp, a propellor (in Arduinoish shape), and a Raspberry. Mostly I use the Attiny boards for anything involving PWM as they have a very nice timer and can cough up 40ma/pin. Non-PWM stuff or early debugging I use one (or more) of the Arduino clones for the serial out (no uart on the attiny85). For more "fun" oriented stuff I use the Launchpad, it has some features that the Atmel
  12. Interesting concept, I like it. 17v seems excessive, most cars charge at 13.7 to 14.7v, over 15v with significant amps can/will boil the battery. The final voltage at the battery is what matters of course, the PSU may droop down to that point. Have you given it a test run yet? What sort of amperage are you expecting into the battery?
  13. Whoa copy/paste fail, whoops :? http://www.digikey.com/product-detail/en/PLF1C271MDO1/493-3018-ND/1136108 That's what it was supposed to be.
  14. You'll definitely need a fair bit of ripple current. If the regulator doesn't care about having "too much" capacitance on the output you could always use something like this: http://static.fjcdn....66a_4241306.jpg EDIT: This: http://www.digikey.com/product-detail/en/PLF1C271MDO1/493-3018-ND/1136108 The only 22uf cap with enough ripple current that I could find is this character: http://www.digikey.c...11-1-ND/1830023 Not exactly convenient or cheap.
  15. I'd pull the chip off and see if the board still works without it. If it does, onward! If not, I'd grab a new chip and put it on if the chips are cheap enough.
  16. I got mine today (they actually were delivered yesterday I think). They work great! Amazingly bright, too. The 1m strip eats 1.2 amps or so at full burn, for reference purposes. Thanks!
  17. Got my strip and played with this a bit. It works great! Here's all 60 LEDs in my one meter strip with flowing colors. Max duty cycle is limited to 40, partly because these things are quite bright and partly because at full burn the strip eats ~1.2 amps and my regulator starts getting rather toasty. The LEDs are supplied with 5v (actually 4.5v after the LDO after coming out the USB3 port) from a seperate power board, the MSP430G2553 is on a standard Launchpad. #include <WS2811Driver.h> byte leds0[180]; WS2811Driver ledStrip; // uses P1_7 as datapin connect to DIN on strip void
  18. Wonderful! I should have a strip showing up soon, I'll give this a whirl.
  19. There're some *very* cool prizes there. That energy scanvanger just cost me half an hour of research time! I'll have to actually work on the project I've been contemplating. I wouldn't call it epic, but it's at least interesting
  20. Energia wants void loop() No variables can be passed to it, and it dislikes having a void inside the ()s too.
  21. As a note, if you drive a manual transmission car you will not lose power steering if the engine shuts off, unless you take it out of gear or put the clutch in. The same goes for power brakes. Automatic transmission cars you may or may not lose both, depending on how well the torque converter freewheels.
  22. Thanks! I tried the library, it refused to write anything but strings. All my attempts at telling it to write anything else resulted in 210 being stored. Never did figure out why! It may well have been operator error. Probably was, really. The flash reading and writing stuff is pulled out of the library (mspflash.cpp, to be specific) and changed slightly to suit my purposes.
  23. That's a nice way to have the frequency choice set up. I like it. I'll remember that.
  24. It's grown somewhat, now it can be programmed (first, second and third push-time targets, plus the wiggle room) via that same one button. It saves the combination to flash when it exits programming mode, and loads it from flash on boot. The comments in the code aren't all accurate anymore, I haven't gone through to re-comment it yet. Flash read/write is ripped out of the back end for the Energia flash library (which I could not convince to store anything but a string). There are plenty of places for streamlining and general efficiency enhancement, but it works! Next up is convincing
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