Search results

  1. hexreader

    Can a step-down transformer be used as a step-up transformer?

    My understanding of theory is almost nil, but I am a very practical person, and have messed around with electronics a bit. My simplistic half-understanding is this: Feed mains into a lot of turns with a lot of inductance, and both the wire resistance and the inductance will resist current flow...
  2. hexreader

    Can a step-down transformer be used as a step-up transformer?

    I am clearly not going to convince anyone here. All I ask is that when you try it, you have a fire extinguisher to hand, and have somebody standing next to the mains breaker.
  3. hexreader

    Can a step-down transformer be used as a step-up transformer?

    I am confused. Assuming that the OP was planning to put 120V mains (or is 100V?) across the 12V winding, AC at 50/60 Hz, and assuming that the transformer is a typical power-supply type transformer, I would have thought that burn-out is pretty much inevitable after a matter of a few seconds, or...
  4. hexreader

    Can a step-down transformer be used as a step-up transformer?

    Surely putting 100V across the 12V winding will cause so much current to flow, that the 12V winding will burn out very quickly. Or if the current is limited to what the 12V winding can withstand, there will be a lot less than 100V across the 12V winding. Unless you plan to use PWM to limit the...
  5. hexreader

    unknown LED Driver IC

    I would be fairly confident that this is a PIC microcontroller. Probably PIC12F629. Possibly PIC12F675. Possibly PIC12F683. Be aware that a replacement PIC would need to be programmed before it will do anything. Hope this helps
  6. hexreader

    ppm???

    Parts Per Million (probably) Strangely, Google seems of limited help, so this is a fair question. Are you asking because you are using a crystal? ... or some other reason. There are other uses for the ppm acronym, so I may have guessed at the wrong one
  7. hexreader

    Coding, Modulation & the relationship between frequency and data rate

    In your application, then probably yes. No, I do not think that there is any need, unless you are building your own Modem Yes, I think this is true.
  8. hexreader

    Coding, Modulation & the relationship between frequency and data rate

    QAM is used by Modems for transmitting data across analogue circuits. I do not think it is normally appropriate for use with simple square wave digital transmission. The (analogue) frequency of a perfect square wave is infinite, and contains all frequencies. But what you are talking about, when...
  9. hexreader

    car remote

    Car manufacturers spend millions of dollars making sure that thieves cannot copy the signal from your remote. The remote will send a different code each time it is used, and only your car knows what code to expect next. .......or something like that. I do not know the exact details. So going...
  10. hexreader

    Infrared xmitter range

    You can get more current to the IR LED by adding a transistor driver stage. Maybe something like the the circuit used here: http://www.gedanken.demon.co.uk/infra-red-tx/ (just the part of the circuit with Q1, D2, R2, R3, R4) This should increase the LED current from about 50mA to...
  11. hexreader

    Infrared xmitter range

    You need to tell us what transmitter and receiver you are using and how the transmitter is driven. You can increase the current through the transmitter, as long as you do not exceed the maximum average current for the device. Or you can transmit pulses from the transmitter, to get more...
  12. hexreader

    Infrared xmitter range

    Do you mean "please" ? Do you mean "to" ? Do you mean "the" ? Do you mean "to" ? You need to tell us what transmitter and receiver you are using and how the tranmitter is driven. It is hard to give help withut knowing the details. In general, range is increased by incresing transmitter...
  13. hexreader

    0-99 Counter

    @Laplace - nice catch. Makes sense now. Thanks @tyhahn92 - presumably using the D output from the first stage as the clock input to the second stage would work. Not sure if an inverter would be needed.
  14. hexreader

    0-99 Counter

    You did well to get this far. I reckon you have earned a good homework mark already. My reading of the datasheet suggest to me that your circuit shoud work. (which suggests that I do not understand it properly) How about trying connection of the first CLR signal as the clock to the second...
  15. hexreader

    0-99 Counter

    I think you need a logic gate on each '163 to reset it when it gets to 9 (or maybe even binary equivalent of ten) But I am giving the game away! Had a look at the datasheet, and apart from the permanently asserted CLR problem, I see nothing wrong. I am very rusty on logic circuits...
  16. hexreader

    0-99 Counter

    I will need to read up on the datasheet to see what is wrong. The first obvious error in the diagram is that CLR seems to be permanently asserted. Note the bubble at the input to CLR. Maybe fix this while I read up.
  17. hexreader

    0-99 Counter

    I have given you a hint. I do not want to tell you the answer. I will give another clue though. What does your counter normally count up to? What do you want it to count to?
  18. hexreader

    0-99 Counter

    You have missed a vital clue in the question. The question is not clear, but it looks to me as though the counter should be a decimal counter, so the use of "HEX displays" might be misleading. Hex displays can show decimal or hex. Can you clarify whether you are displaying a count to 99...
  19. hexreader

    Help with cable

    Whilst I know very little about camera modules, I am pretty confident that the signals on that connector will travel nowhere near 50 feet. I suggest that you forget this idea straight away.
View older results
Top