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  1. (*steve*)

    Power bank PCB

    Why not just buy them and use the enclosure they already have? I doubt you'll get the source you want for the price point you mention. You may, if you order a far higher qty.
  2. (*steve*)

    I'm an electronics newb, and I need help with my first project (static grass applicator).

    The pictures of the remaining parts of the negative ion generator shows the part of the negative in generator which actually created the high voltage. Also, if you can post your images here it would be better. What voltage does your negative in generator run from. Is it the same as what the...
  3. (*steve*)

    OPA in mic preamp

    Triple snap
  4. (*steve*)

    OPA in mic preamp

    I don't understand what "the method of raising" means. Autocorrection failure? You're correct that the op amp has no idea whether the supply is single ended our not. My point was that you need a mid rail reference. You can do that with a pair of resistors, but a double ended power supply is...
  5. (*steve*)

    Power bank PCB

    Why not use a single large battery then? Why do you need 300 to 600 USB ports in a single enclosure? Perhaps you can tell us what you're actually planning to do so we can give you a good solution rather than getting distracted by your solution.
  6. (*steve*)

    Designing my first basic circuit - But have a few Questions

    The is no reason that you can't charge the battery while you're using it. There is no better place to measure the battery voltage than across the battery. Your load is only 8/100ths of an amp. Ant charger capable of 100mA or more will be able to keep the battery charged even while the motors...
  7. (*steve*)

    6 layer pcb stack

    1 oz copper is 1 oz per square foot. 2 oz copper is twice as thick and can this carry twice the current.
  8. (*steve*)

    What component is this?

    It's an inductor.
  9. (*steve*)

    Designing my first basic circuit - But have a few Questions

    There is no need for resistors The battery is probably 9Ah and will need a charger that supplies far less than 10A. Other than that your block diagram is basically correct. Normally we would draw it charger, battery, controller, and motor in that order from left to right. I'm assuming you...
  10. (*steve*)

    Help With Circuit

    Your circuit effectively has positive feedback rather than negative feedback. It will act more like a Schmitt trigger than a current sink. To work, the resistor needs to be between the source and ground and the non inverting input connected to the source of the mosfet.
  11. (*steve*)

    HELP. transmit a wireless signal to

    I would have recommended a remote control module from eBay, but you don't want that. Perhaps you have a local hobby shop that sells remote control modules or something similar.
  12. (*steve*)

    Help identify electronic components

    Is there anything written on those black components?
  13. (*steve*)

    OPA in mic preamp

    The battery you're looking for is an A544. It's a little larger than I recalled (I was thinking of the thinner 12V battery for remote controls). Actually, here is the smaller one. The A544 looks like a reasonable compromise -- it will have more capacity than the smaller battery. Some obvious...
  14. (*steve*)

    motors start when i touch arduino port

    I've placed code tags around your code so it's at least readable now. I don't have time to read all of that code and make sense of it. Perhaps you have a link to where you got it from? There's clearly some other hardware involved. Do you have exactly the same hardware as used originally, and...
  15. (*steve*)

    motors start when i touch arduino port

    That is definitely code. Placing it between code tags would be a good idea. Have you tried debugging the code yourself?
  16. (*steve*)

    Help with Circuit board needed asap

    A conductive pen is of very little use when there is significant current.
  17. (*steve*)

    digital multimeters

    Yes, or both. And maybe other things too. Perhaps you can give us the full question on your assignment with whatever background it gives to the problem.
  18. (*steve*)

    Mosfet's

    The numbers mean that it's one of these. Probably the easiest, fastest, and cheapest way for you to get them is here. It is possible they are failing due to some other fault though. If you replace the full set and they fail immediately (or at least very quickly) then you have something else...
  19. (*steve*)

    OPA in mic preamp

    Yes, but not audio ones. You need a mid rail reference point or your op amp won't be able to amplify both halves of the audio signal. In this case I've given you a voltage divider with an impedance similar to the resistor that should be connected to a stiff rail. This will work, at the...
  20. (*steve*)

    OPA in mic preamp

    Change R2 to 22k, remove C4 (R2 goes straight to ground). As another 22k resistor from +9V to the top of R2. If you want to you can connect the unused C4 between +9V and gnd.
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