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  1. J

    Making a 5v digital signal

    You can't have a frequency without a duty of <100% and >0% if you need the same ON time as OFF time then you need a 50% duty cycle of a 5V square wave The formula for the frequency is in the image I posted. You know the frequency, so use your algebra skills and work backwards. Best to pick a...
  2. J

    Making a 5v digital signal

    If you need exactly 50% duty cycle then an IC or uC with PWM output pins would probably be the route to go. If you can do with a little error on the duty cycle a 555 timer with pin 6 connected to pin 3 via a resistor will give you a very close approximation to a 50% duty cycle
  3. J

    electrical component questions

    ... and magic smoke would appear and then the circuit would stop working. diodes are not made to breakdown in the reverse direction, unless they are zener diodes.
  4. J

    multisim simulation

    I don't see why not. it has a model for the LM339
  5. J

    where to get blank circuit boards

    Now is a bad time to go for copper. I just took a load in to the recycling center and got over $3 a pound. Wait till scrap prices go down, late summer early fall. You might have better luck finding some with a cheaper price tag
  6. J

    Stepper Motor controller in development

    L298/L297 ~1A can be paralleled LMD18245 ~3A can be paralleled http://www.divms.uiowa.edu/~jones/step/circuits.html limit switches have more to do with the driving software and not so much with the hardware driver of the motor. You reach a limit and the software stops sending signals to the...
  7. J

    adjusting the LM317LZ IC

    http://www.reuk.co.uk/LM317-Voltage-Calculator.htm does this help? You would better going for 1.5V output.
  8. J

    Stepper Motor controller in development

    But it ain't gonna be that cheap if you do something like greengiant said. Every part that you add to the circuit is just gonna up the cost. Probably more so then if you bought a chip that had more current capability from the start. You still haven't said what your requirements are. Does this...
  9. J

    Stepper Motor controller in development

    why are you so stuck on the uln2003?
  10. J

    Powering multiple circuits and a motor with Batteries

    as long as the motor voltage falls between 6 - 12V then I don't see why not. What type of battery you need and how big will depend on the current draw of the 3 components of your project. Do you know what the current requirements are?
  11. J

    Stepper Motor controller in development

    read the datasheet, if the chips are able to be paralleled or another way is possible to up the amperage then the datasheet will tell you how to do it. I never really looked into this chip, but 500mA to drive a stepper for a cnc is way to small. I have 3 NEMA 17 motors and they need over an...
  12. J

    Class A amp questions

    Yep, that explained it. This then effectively keeps the transistor close to it's Q-point which would help maintain stability of the circuit. I get that now I kinda assumed that when I started, but it always nice to see the math prove the theory. I am not sure how you measure power gain, as...
  13. J

    Sky Remote

    So the answer to your question is NO it will not be PERMANENTLY damaged, though it will need to be reprogrammed, which you as a consumer may not be able to do yourself.
  14. J

    Sky Remote

    Ask your friend this, what exactly in the device would get damaged from a lack of power for 10 minutes? Because I am 100% positive that nearly all the components inside the device would not be damaged by a lack of power. I won't say he is wrong, but I would love to hear his explanation first...
  15. J

    DC power supply

    I would also recommend steve and KJ's option. The over exuberant dave at EEVblog is building a very nice lab PSU. You could even incorporate Olivers idea in if you use the PWM option that dave speaks about in part 4 of the video series by using a uC.
  16. J

    Class A amp questions

    always helpful even if clouds still swirl around my head. :) we're talking impedance because of the AC signal input? Would the impedance of the biasing network be R1+R2 or just R2? This is where I lose you. What does "stiff" mean? The website I linked to said the biasing current should be...
  17. J

    Class A amp questions

    I bought this tip31 transistor and it says on the package good for audio. I figured why not mess around with it in simulation to see what it is capable of doing. Here is my results. I followed this guide for the design. http://www.electronics-tutorials.ws/amplifier/amp_2.html Here is what I...
  18. J

    electrical component questions

    That inductor is just part of a transformer, the secondary side. The only thing it is doing is either stepping up or down the voltage. Its output will still be an AC voltage sine wave. You can ignore the fact that it is an inductor and that it's output will be the same sine wave as the input to...
  19. J

    simple multiplexing

    Harald already pointed out you only need 6 bits for a value of 50 decimal. You can just as easily get rid of the last two bits and use the first 6 bits. It all depends on what you consider the most significant bit. (MSB) Not in all cases, but in most, the MSB is the left most bit in a multi-bit...
  20. J

    Circuit Simulator program request [HELP]

    Multisim will do this. You can find free copies if you look around. proteus also has animated models.
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