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  1. KrisBlueNZ

    Power for Multiple DC Motors

    Sorry, I didn't realise that your "motor driver board" on the right is just a breadboard! You should have a diode across each motor, e.g. 1N5404, with cathode connected to the positive side, to protect the transistor against back EMF from the motor, which is an inductive load. Although that...
  2. KrisBlueNZ

    Power for Multiple DC Motors

    That looks like a good setup. I can't comment on the diodes unless you give us a reference for the motor driver board. But if you've followed the instructions for connecting motors to the board, you should be OK. Use a fuse in series with your battery! Say 6~8A slow blow.
  3. KrisBlueNZ

    Chicken Coop Door Opener

    Yes, go for it.
  4. KrisBlueNZ

    Chicken Coop Door Opener

    I should have mentioned using a microcontroller. This is a really obvious case where a microcontroller could hugely simplify the hardware required, improve the behaviour, and provide opportunities for improvement. A little 8-pin device would be plenty. A PIC12F675 for example. The I/O could be...
  5. KrisBlueNZ

    Hello World 1.0 by Dave of Brighton

    Hi Dave and welcome to Electronics Point :-) Thanks for introducing yourself.
  6. KrisBlueNZ

    Chicken Coop Door Opener

    The system won't be reliable unless it knows the state of the door. If your friend presses his remote control button during daylight hours to close the door, when darkness falls, the automatically generated pulse will open it, and it will be in the opposite of the expected state until another...
  7. KrisBlueNZ

    Power for Multiple DC Motors

    The current required by those motors adds up pretty quickly to several amps, which is more than you should be drawing from AA cells, especially primary cells (non-rechargeable). How heavily are you loading the motors? Under load, at 12V DC, at 1.5A per motor, the total is 6A which is way too...
  8. KrisBlueNZ

    Re-wiring a powered Subwoofer

    Hi Wolfgang and welcome to Electronics Point :-) It's DC.
  9. KrisBlueNZ

    Hello from S. Ohio

    Hi Burnmeup and welcome to Electronics Point :-)
  10. KrisBlueNZ

    Faulty AC-DC Adapter?

    It sounds like this adapter is a mains transformer type (i.e. the heavy, old style, not a light-weight switching type) with multiple secondary voltage taps to choose the output voltage, and no output regulation. These are inherently poorly regulated; the output can have a lot of ripple at twice...
  11. KrisBlueNZ

    Radio Controlled communication

    I don't know whether this will help at all, but it's possible to buy pretty cheap video repeater units that transmit video in one direction and infra-red remote control commands in the other direction. These are intended for use in houses where you have a single digital TV or satellite decoder...
  12. KrisBlueNZ

    RC-filter for electret mic and USB sound card

    Yes, I agree. I should have made it clear that I wasn't recommending the inductor; I was just answering the question about feasibility. Actually I was hoping that the inductor value would come out so high that I could say it wasn't practical, but unfortunately Digikey did have a 220 mH inductor...
  13. KrisBlueNZ

    RC-filter for electret mic and USB sound card

    I suppose you could connect an inductor across the microphone. You would need a DC blocking capacitor in series with it. This forms a series tuned circuit but with a large capacitor, the resonant frequency could be so low as to be irrelevant. But the inductor would need to be a pretty high...
  14. KrisBlueNZ

    RC-filter for electret mic and USB sound card

    Hi Even and welcome to Electronics Point :-) An electret microphone needs DC bias. The circuit board must be providing this. When you connect the capacitor in series, you remove the DC bias and the microphone stops working. I can't think of any simple way to do what you want.
  15. KrisBlueNZ

    Designing a Time Delayed Relay

    That's looking pretty good. You haven't corrected the R3 value. I understand why you didn't include all the important information on the schematic. I always use the schematic as the basic design document, but if you have an integrated system that stores the BOM separately, then I guess it's...
  16. KrisBlueNZ

    design 1A current limiter for my 300V dc supply

    You'd better have some pretty big heatsinks!
  17. KrisBlueNZ

    Designing a Time Delayed Relay

    That's looking good! Now I can see it properly! R3 should be 220R not 220k R1 and R14 should be marked "fusible" C1 and C14 should be marked "X2" - this is a special requirement You should probably indicate the capacitor types for various other capacitors. When I've marked them on my schematic...
  18. KrisBlueNZ

    How to communicate between two devices?

    You only really need a paired radio remote control transmitter and receiver with a single momentary or data input. Any pair that will transmit arbitrary data can be used to send either a logic 0 for one state or a logic 1 for the other state...
  19. KrisBlueNZ

    How to communicate between two devices?

    I don't think that would be a problem. But it would help if we knew more about the LED(s) you plan to use, and how much current you will be running them at - in both normal mode, and while braking, and what run time you need between recharges.
  20. KrisBlueNZ

    Designing a Time Delayed Relay

    1. Corrections as marked to bridge rectifier connections 2. Suggest not using "humps" to indicate crossing wires with no connection 3. You sneaked in a substitution - Q1 from TIP29B/C to TIP31C. That's fine. 4. That image is barely readable, and it's in JPG format, which is designed for...
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