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  1. Fish4Fun

    Help in GSM Shield

    Brian, Methods of enabling the board are discussed beginning on page 6 of the linked document, and they are: 1) Power button. 2) TTL level signal on key "PWRKEY" 3) Set Jumper JP1 to "AT" You should read the details about each mode in the document you linked. Fish
  2. Fish4Fun

    Small dc motor controller options

    So, let me see if I have this straight: You want a device that accepts a 0-10V control signal and outputs a regulated current range between 50mA and 766mA to drive an aquarium pump to produce a special effect; you prefer it be in a sealed, waterproof enclosure, but you think the existing...
  3. Fish4Fun

    Small dc motor controller options

    What is the switching time-frame? Are you turning it on and off more than 1 time per second? If not, why not simply use a relay and the existing power supply? Even @ 2 times a second for intermittent periods a good quality relay will do the job. Most DC brushed motors work best // longest if...
  4. Fish4Fun

    simple 24V DC brushed motor driver circuit with relays help

    Supplying//Controlling 60A @ any Voltage is a non-trivial business. You would be MUCH better off to go with a motor designed for 1) Speed Control 2) to be driven from line power. Assuming the wheelchair motor is a large brushed 24Vdc motor, @ 60A this would be 1.4kW. This is likely WAY more...
  5. Fish4Fun

    Hot Wire Cutter Power Supply

    sferrari, You might give some serious consideration to forgoing all of these excellent suggestions and consider a simple approach: Adjust your length of wire to the power supply you already have. @ 2 ohms per foot 5 feet would be 10 ohms or roughly 1.44A (A typical 12V battery charger's...
  6. Fish4Fun

    H-Bridge Circuit Design

    Kris, Yes, it is exactly those data sheets that got me started down the path I was on; however, I really wanted to build a test circuit that allowed infinite 0 & 100% duty cycle....so I read an application note that showed using a 555 timer circuit to provide the HS floating voltage .... and...
  7. Fish4Fun

    H-Bridge Circuit Design

    Kris, A little light came on in my head last night; even with the dense fog, it was pretty clear: I think I have WAY over thought the floating power supply! When I first started looking @ modern H-Bridge designs I kept running into various tricks to provide a floating high-side voltage to...
  8. Fish4Fun

    Need advice to choose components for a project

    I guess the most important question is what is this project's budget? And the second most important question is how precisely do you want to track the monkeys? You mentioned the distance was < 10m, suggesting an area of < 100m^2. You might consider a surveillance camera and a PC with some...
  9. Fish4Fun

    my engine control unit project

    russian, Again, let me emphasize I know little about cars. Do you know if the processors generally used in automotive applications are JTAG compliant? If so, perhaps it would be possible to "take control" w/o completely replacing everything requisite to make the systems work. Assuming you...
  10. Fish4Fun

    H-Bridge Circuit Design

    Kris, Thanks for the response! 1) Mosfet: My dyslexia does not ALWAYS migrate to actual circuits. (!me) 2) D4 is likely not important in any case, but the filtering provided by D3, in the actual circuit, removes a lot of transients and switching artifacts; likely more careful attention to...
  11. Fish4Fun

    Need advice to choose components for a project

    You have basically outlined: Bluetooth RFID and portions of the ISO7816 smart-card protocols The problem is not finding compliant devices, the problem is making your devices compliant. It might be better to give a detailed description of what you are trying to achieve, then perhaps someone...
  12. Fish4Fun

    my engine control unit project

    Hey russian! I am NOT a car buff, but don't all cars sold (in the USA) since some time ~1997 have to be ODBC compliant? If so, why not just interface with the computer that is already there? The on-board computer is already connected to every sensor in the vehicle, and it already monitors...
  13. Fish4Fun

    Need help with an IR project

    The UL listing on the plastic cover is 5A @ 125V 625W max; however, the relay itself (iwhen you take the cover off, hehe) is a 10A relay. Regardless, it would be a comparative walk in the park to connect an existing RF remote to drive any size relay you required. Fish
  14. Fish4Fun

    Help with Tiny Monitor Cube Thingy

    OK, first off let me say, "wow that is one heck of a uController!" I assume you have experience with the ARM Cores? If that is the case then you are way ahead of me, lol. I have dabbled a bit with some of the older ARM uControllers, but I was in way over my head even back then. Even if you...
  15. Fish4Fun

    Need help with an IR project

    Hrmm, Lowes and Home Depot sell RF remotes for X-mas lights. The Single outlet model is usually ~$10 and the 3-Outlet version is usually ~$19. I use them for Lamps around the house, they are great! I sure wouldn't build one for what they cost. Fish
  16. Fish4Fun

    H-Bridge Circuit Design

    Well I had some time to play the past few days, and I got tired of reading about all of the caveats and peculiarities involved with the various HS drivers and H-Bridge modules, so I thought to myself, "how hard can it be to build a floating supply?" So I sketched up the attached schematic...
  17. Fish4Fun

    "Dimming" LED's with pot/rheostat by progressive shutoff

    Chocolate Sheikh, If you are simply trying to "Dim" an LED light, this is best achieved via PWM using a buck or forward converter with a current feedback loop. Depending on the efficiency requirements, power level and voltage source involved there are a number of solutions, but they will all...
  18. Fish4Fun

    FM Transmitter

    GreggSudduth, If I might suggest...when requesting bids/proposals for technical devices/software/firmware you need to do your due-diligence. Examples follow: 1) "Short-Range" is almost meaningless. It could mean a mW transmitter with a 1 meter range like an automotive MP3 player that...
  19. Fish4Fun

    Help with Tiny Monitor Cube Thingy

    wow Bad_Syntax, There is a GIANT gulf between computers and devices with embedded controllers. To build a completely functional prototype of the "box" you have described is going to be very expensive. For a quick primer on VGA: http://en.wikipedia.org/wiki/Video_Graphics_Array For an in...
  20. Fish4Fun

    Need a special motor for a magic trick

    Hydraulics.& pneumatics can be silent; your link is for a "credit card" sized device, so I assume you need very little actual power. A simple solution might be a pair of syringes coupled by a piece of tubing: press one in, the other moves out. For a mechanical advantage use different diameter...
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