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  1. (*steve*)

    hacking rc helicopter - need help

    Can you show us a circuit diagram, tell us the power requirements, and describe how you have bypassed the power to the arduino?
  2. (*steve*)

    Special Led Chip Array With Step Down Converters.

    I'm intrigued, what urban agricultural applications are there where the cost of power for growlights doesn't make it cost prohibitive? Also, why do your LEDs cost so much?
  3. (*steve*)

    Which relay should I use?

    *facepalm*. The controller produces the 3 phase AC to drive the motor. So the AC voltage rating on the relay is important. However, stopping drive to the motor to reconfigure is still a good idea. Placing I inside the housing of the motor though... That may be a tough ask. How much room is...
  4. (*steve*)

    Testing mAh of a battery?

    Well, divide it by 8 to get the 8 hour discharge current in mA. e.g. 1600mAh equates to 200mA discharge current for a projected 8 hour discharge. Then to calculate the load resistance, get the battery voltage and divide by the current in AMPS to get the load resistance in ohms. Let's say it's...
  5. (*steve*)

    Electronic math

    Well... Depending on what you're having trouble with, it may be general mathematics and not electronics specific. Because some of the math isn't intuitive, I don't know of a site which uses electronics examples for teaching the underlying math. Can you give us an example of the sort of thing...
  6. (*steve*)

    Which relay should I use?

    This relay may be suitable. DPDT, 30A contacts. Place them in parallel to get 60A. Rated for 125VDC with a 12V coil.
  7. (*steve*)

    Ceramic Capacitor vs Electrolytic Capacitor

    The resistance of the larger capacitor probably results in a lower current than that from the higher voltage capacitor.
  8. (*steve*)

    Which relay should I use?

    Well, if you're shifting gears, you take the load off the gearbox while changing gears (even in an automatic gearbox). The problem with picking a random moment to switch from wye to delta (or vice versa) is that you'll get huge voltage spikes with enough energy stored in the inductors to...
  9. (*steve*)

    Which relay should I use?

    I've done some research on delta/wye switching. You're switching fairly significant inductive loads. If this is done under load, I'm not surprised that the relays don't last long. Are you switching under load? Can you remove power briefly while you reconfigure the motor? Doing this...
  10. (*steve*)

    741 OpAmp

    See this thread. The first post contains an image with the correct pinout.
  11. (*steve*)

    741 OpAmp

    Yes, Dave was very much on a power trip. He's only interested in power. Mostly the apparently high (but unstated) power requirements you seemed to demand from the 741. Anything more than 18V (36V in unusual circumstances) at more than 10mA is going to be beyond its capabilities...
  12. (*steve*)

    Problem With OPAMP

    Without inductors or switched capacitors (but I don't think that's relevant here)
  13. (*steve*)

    Spray to clean corrsion from a PCB?

    See here. Note that it is far better if you can ensure that the chemicals don't get into the electronics as they can cause as much damage as the corrosion.
  14. (*steve*)

    Wifi Transmission; Energy involved in sending a Wifi Signal

    You multiply: the voltage (required by the transmitter and produced by the power source) by the current (drawn by the transmitter) by the time (that you want the transmitter operating -- could be minutes, hours, or days) That gives you an amount of energy required. From that you can...
  15. (*steve*)

    Really silly electrical conundrum

    Another trick is that if you have a battery holder which has two batteries in series and where the polarity of the batteries is not obvious, placing one the wrong way around will give you very close to 0V out.
  16. (*steve*)

    Which relay should I use?

    Why not use mosfets to switch the current? What are you actually trying to do? (I.e. What function will this relay perform?) What do you mean "it must be a 5 pin relay"? SPDT? If this is three phase, don't you need 3 relays?
  17. (*steve*)

    Amps are big.

    Well... Each bulb requires 20/12A = 5/3A = 1 2/3A, so each string will be 1.667A times 6 strings, that's 10A.
  18. (*steve*)

    How many watts solar panel to power this Fan?

    The motor will require a high current to start turning. Did you try spinning the motor by hand? The panel may be able to keep it turning. Practically, this won't be much use as the motor week stop again as soon as the first cloud appears :( It may be best to have the panel charge a battery...
  19. (*steve*)

    Unknown components on this circuit board please help

    As stated above, the 7530 is a dual mosfet and is clearly used to control the 4 load outputs.
  20. (*steve*)

    Need help - TIP122 transistor

    You probably have the connections wrong. The most likely thing is that you have assumed that the centre connectors are common. They aren't always arranged that way. Did you check? If the relay really is of the type indicated in the photo on the website, then the datasheet can be found here...
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