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  1. (*steve*)

    Dr Who's K9 circuit help...

    There are a few ways to do it. Both involve having routines that do one step and immediately return without delay. For the light panel, that is to choose another 4 LEDs and change the display to show them. For the character matrix that is to scroll the display one position to the left and...
  2. (*steve*)

    buying a THD meter

    There is a link on that page to the replacement model which is priced identically and operates from 110VAC to 415VAC
  3. (*steve*)

    buying a THD meter

    Are you referring to measuring the affect on the mains waveform by the non-resistive load characteristics of (in this case) a LED driver? Just curious, because all my THD measurements have been on signals rather than power. (This told me a lot). This seems to be near your price point (and...
  4. (*steve*)

    Why is this LED not 20 Watts?

    I'm pretty sure we're onto that.
  5. (*steve*)

    Nice relaxing day.

    If they did that, they might rise to levels considered cheap. :-) I think it's dangerous to generalize. I'm sure there are zealots on both sides of the political spectrum. From the perspective of an outsider looking in, neither your presidential nor senate outcome are unexpected given the...
  6. (*steve*)

    Calculating resolution.

    Oddly enough that was the same argument I used to convince myself that you must subtract 1.
  7. (*steve*)

    Nice relaxing day.

    In other news, there are alternatives to Canada for sad Americans.
  8. (*steve*)

    Nice relaxing day.

    If the predictions hold true Lisa Simpson will run for President in 2020 and WIN!
  9. (*steve*)

    Vibrating Metronome Project

    The diode across the motor will stop it quite quickly, Aside from that, I think you need to try it to see how it goes. I've had devices that pulsate the vibration quite quickly, so it's not beyond the realms of possibility.
  10. (*steve*)

    Vibrating Metronome Project

    If you go to this page you'll notice that for a conventional 555 circuit the time the output spends low is less than the time it spends high. You need to calculate values so that your low time is about 0.1 seconds and the high time is in some suitable range. Yes, you can have a potentiometer...
  11. (*steve*)

    help me plz

    You could also go to http://alltransistors.com/mosfet, search for the IRFR014, select it, click on the "transistor equivalent substitute" link, blank out the package type and hit search. This does not compare all specifications, but it does compare many of them. It should give you a longer...
  12. (*steve*)

    help me plz

    Can you tell me what the important specifications are? Can you show me a circuit diagram? Can you tell me what device the mosfet is in and what function it performs? Without at least one of these I have no hope of answering you in a way that is reasonably guaranteed to be correct. Depending...
  13. (*steve*)

    help me plz

    Why the "but"? You didn't ask that question. Ok... I'll take a look. Irf540 - this I larger and has a higher gate charge. If switching speed is important, it may not be a good choice. Also the turn on turn off times are significantly different. If the ratio of one to the other is...
  14. (*steve*)

    help me plz

    Hexfet is just a manufacturer's designation for the way they have created the mosfet. In general, high current low Rds(on) mosfets are constructed by making many smaller mosfets an wiring them in parallel on the die. The challenge is to reduce the gate charge and one manufacturer has called...
  15. (*steve*)

    Vibrating Metronome Project

    Sure, 180 per minute is 3 per second. A 555 can easily operate at that frequency. If you can get hold of a small vibrator motor, you could set up a 555 that is on for 200 to 300ms and off for maybe 50 to 100 ms. Turn the motor on when the 555 is off (output low). You will probably want to...
  16. (*steve*)

    Special Project with led and motors

    You might be able to slow the motor by driving it with a PWM controller, but I'm not sure you could slow it enough. Another option would be a further reduction with another gearbox, or perhaps a geared down stepper motor.
  17. (*steve*)

    Trouble understanding shunt resistance for short-circuit current measurement

    In addition to this, you need to Google how to make accurate voltage measurements on the arduino. If you don't operate the arduino from a very stable and accurate 5V source (typical sources are no better than 5% accurate) then you need to know how to deal with this or your readings will also be...
  18. (*steve*)

    Trouble understanding shunt resistance for short-circuit current measurement

    Let me give you a helpful answer. Measuring the short circuit current of a solar cell requires the voltage across it be far less than the open circuit voltage. For a single cell the open circuit voltage well bea little less than the bandgap voltage. Let's say it's 0.55V. To measure the Isc...
  19. (*steve*)

    Group Project

    No. It's whatever we want it to be. Most of us are here to help other people do stuff out to get help doing stuff. We generally don't do stuff together. We are not a hackerspace.
  20. (*steve*)

    328P datasheet

    Find a programmer that interfaces via the 6 pin connector on the arduino (or the 6 pins if you're using a bare chip) and most of your bucking problems will go away. It is always possible to set it up so you need high voltage programming, but unless you're careless the in circuit programming...
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