Search results

  1. Xeno Xenox

    Clean square waves using a 555 timer?

    @dorke: You are correct. I failed to connect the control pin bypass capacitor to ground in the working circuit. Thank you for catching my mistake. The same capacitor appears to be connected properly in the failing circuit. I will use my 10X probe setting in the future, but shouldn't it be...
  2. Xeno Xenox

    Are product recommendations off-topic?

    I have several cheap multimeters and I'd like to invest in a high quality upgrade. My primary use case is low-voltage (under 15V / 1A) electronics, but I'd like something I can safely connect to any of my house mains (in the United States) and to higher voltage circuits in household devices...
  3. Xeno Xenox

    Clean square waves using a 555 timer?

    After looking at the scope traces for these two circuits and comparing the different high levels of the two square waves produced, I realized the transient on Vcc was larger than I remembered and might still be the culprit after all. When I get some more time to experiment, I'll try using the...
  4. Xeno Xenox

    Clean square waves using a 555 timer?

    Ok, here are some photos of a couple of quick builds. I'll begin by showing you photos of the circuit that works. This circuit uses a diode and variable resistor to hit a 50% duty cycle. I'm hoping the success of this circuit will reduce concerns about long wires, solderless breadboards, etc...
  5. Xeno Xenox

    Clean square waves using a 555 timer?

    I will try to make time tonight to build the circuit and share some photos.
  6. Xeno Xenox

    Clean square waves using a 555 timer?

    The probe was set to 1x. I've built it several times and in several different ways. I can build it again and take a photo, if you like -- but I suspect it's 100% reproducible for anyone else who wants to try it. :) If someone else builds it and it doesn't exhibit the problems I mentioned...
  7. Xeno Xenox

    Clean square waves using a 555 timer?

    Chris, I used a bench-top power supply (a TekPower TP-3005D-3) and scoped the Vcc pin. The voltage was stable.
  8. Xeno Xenox

    Clean square waves using a 555 timer?

    Thanks again, everyone! I'm convinced that the "overshoot" I was seeing wasn't an overshoot at all, but rather a feature of the circuit. I've confirmed it on multiple NE555 chips, with and without loads. Here's the output again: The trace rises to 9V (Vcc) as expected and stays there for...
  9. Xeno Xenox

    Clean square waves using a 555 timer?

    @Harald Kapp : Thanks for the link to the other discussion. It gave me several things to try. @dorke : If I'm still having problems after trying the suggestions in Harald's link, I'll post a photo of the build. The scope and probe read clean square waves off other circuits just fine. If it's...
  10. Xeno Xenox

    Clean square waves using a 555 timer?

    I'm experimenting with simple circuits to generate square waves, for use as inputs and clock sources for use in more complex circuits. I tried the "50% Duty Cycle Astable Oscillator" based on a 555 timer from this site: http://www.electronics-tutorials.ws/waveforms/555_oscillator.html Here's...
View older results
Top