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  1. J

    DRV8811 stepper cntrl/drv alternative

    So I have come up against another road block. I want to be able to drive some steppers that have ~3A+ current rating per coil. I like the simplicity of the DRV8811 chip because it has everything I need in one package except for the current capability. Things I would like to have or know how...
  2. J

    Understanding stepper motors - parallel vs. series

    http://www.kelinginc.net/KL23H286-20-08B.pdf If both ways provide the same holding torque, then what would be the negatives of using series over parallel to reduce the current per phase which would also reduce heat in the driver? I am assuming that since the rated voltage and phase...
  3. J

    Surface mount heatsinks

    http://www.ohmite.com/catalog/pdf/d-sink.pdf How does one go about soldering these onto a pcb? My first thought was heating up the ends of the tin rods, but after looking at my boards, this is gonna be nearly impossible since I have surface mount devices within an 1/8th inch of those tin...
  4. J

    What do you call these female pins on digikey?

    The 10 pin header pins on the left most part of the board J1 - J2. I need to connect some wires to these. What is it that I am looking for on digikey? I want to attach them to an arduino uno that has the female version of these pin headers. What would you suggest or use if you wanted to wire...
  5. J

    Stepper motor rated voltage vs max voltage

    I have been pondering on what type of stepper motors to buy for a project I have been putting together for the past couple of months. I found this website http://www.kelinginc.net/SMotorstock.html which has a ton of motors at what seems like reasonable prices. But I am a little confused on a few...
  6. J

    Sizing a motor for a particular job.

    I have got this bright idea to use a dc motor to control my milling bed movement. The mill already has a gearbox with reverse. The way I see it though I could buy a dc motor and have that run the gears that control the mill bed movement. I plan on using a arduino to control the motor. I guess...
  7. J

    is your math any better then mine???

    I need some help, school failed me or it has just been so long that I have become stupid. Latter being the more likely. ;) So please HELP!!!!! I need to put in a chimney pipe, and I want to buy my chimney pipe. But I am having a hard time figuring out the length of the piece between the two...
  8. J

    online skype graphic is not downloading

    Whenever I see steve online, he always messes up my browsers formatting. I get this huge box under his name with the default graphic. So either the graphic is not on the server or I would presume a bad link. Anyway, not something that bothers me a ton, but been this way for a while.
  9. J

    I appreciate this site even more today

    What I mean by the title is that I appreciate this site more now then I ever did. I recently inherited a machinist shop from my grandfather as he passed away about 7 months ago now. So I have decided to start learning the trade. Unlike electronics, There isn't as many machinist that care to take...
  10. J

    Question regarding pass transistors

    http://talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html#58 Why would be the advantage of using one method over the other as posted in the link? Why not just use a 2955 pnp?
  11. J

    Motor not turning on but drawing excessive current.

    I have a table saw that every now and then the motor won't start and it just hums, but the light on the same circuit dims severely when this happens and switch is on. So I know it is drawing excessive current. What would cause this sort of thing? The motor is not seized up as I can turn the...
  12. J

    230v sub. well pump

    How does a 2 wire 230 volt w/ ground pump work exactly without no neutral leg? Can someone please explain to me how this works. Don't you need to make the "loop" so that current can flow, or is that what the ground does?
  13. J

    Picking transistors

    So I want to know how one would choose a transistor for this classic Class A amp circuit given my specs. Also, what would be the power output if this was connected to a standard 8 ohm speaker? Vcc 24V Ic 50mA hfe 50 I looked over at digikey and after a few filters applied I ended up with a...
  14. J

    very shocking ceiling fan install

    So I took on the job of putting in a new ceiling fan today. Not completely thinking I just turned off the switch on the wall and figured good enough. Well was I mistaken, as I started to pack up the light fixture wiring and current regulator, I felt this shock and next a spark with a loud bang...
  15. J

    Help in calculating power numbers for green electricity project

    I am curious in knowing how I would go about figuring some numbers for a project I am interested in doing. My project involves using a wind turbine to produce power to charge some batteries. Very basic green energy system. What I want to know is how much power I will be producing and how...
  16. J

    electric code

    Ok so I am kinda sketchy on the terminology here, but I have recently took on a job upgrading some outside "disconnects" I think this is what they are called. the box containing the main breaker right off the meter box. My question regarding the code is do I need to wire the breaker on the...
  17. J

    3 video card caps blown. Can this be fixed?

    First off I would like to know if fixing these 3 caps will help the video card? I am not sure why these caps blew. I had a pair of wires coming from a motherboard fan that was run through the caps. I used the caps on the video card as a placeholder for the wires. Now I am wondering if the...
  18. J

    Circuit clarification needed.

    Can someone please help explain to me how this circuit works? I am pretty sure I understand how the voltage divider network works. I am pretty sure I understand how the H-bridge works. What I do not seem to grasp is how they use PWM in this schematic to turn the motor at slower speeds in both...
  19. J

    Experienced eyes needed. Finalizing my project.

    Need some experienced eyes to look over my complete design and let me know of any major or minor mistakes I have made. Description: This circuit is supposed to be a trip alarm circuit. When the photocell goes dark(R7) the buzzer should sound for a predetermined amount of time and then the...
  20. J

    Multisim simulation help

    Ok so I am trying out multisim because it has a pspice model for the 4060. I add it to the design and hooked it up exactly as the datasheet shows and what do you know? It won't work... :mad: This should be so simple it's stupid. But someone please tell me what I am doing wrong. Link to my...
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