I'm quite new to electronics in general.

My current circuit setup consists of an incoming sine wave. I use a comparator chip to compare this sin wave to a threshold which results in a square wave train, where the width of each square wave is changed by raising/lowering the threshold. I then use this output to trigger open/close a transistor to allow a separate signal through, which is the signal I wish to use. This setup works great when the frequency of the sin wave is low, however my issue is when running such that the incoming sin wave is higher frequency (on the order of 1-5 kHz) the signal looks like the image below.

Would there be any way to clean this up to remove the decreasing trains after the pulse? My initial though was perhaps the comparator chip, or the transistor cannot work at such frequencies but the spec sheet says they should be fine, and if this was the case I would expect a smooth tail not a drop to a value and then a decreasing tail.

enter image description here


Information that commenters asked for :) Comparator chip: LM311P Transistor: BC337


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Can you provide a schematic including the parts you're using? You can edit your post and use the Circuit Builder tool to draw a schematic right in your post. \$\endgroup\$
    – Matt S
    Commented Jan 30, 2023 at 15:32
  • \$\begingroup\$ Is this causing any issues in the consumer of the signal? Why do you think you need to "clean" it? \$\endgroup\$
    – Eugene Sh.
    Commented Jan 30, 2023 at 15:33
  • 3
    \$\begingroup\$ Take another look at the signal using a x10 probe. \$\endgroup\$
    – Finbarr
    Commented Jan 30, 2023 at 15:40
  • \$\begingroup\$ Your schematic does not show the relationship between the "Experiment voltage" and Vcc or GND. Without this, any analysis will be incomplete. Please post a complete schematic. \$\endgroup\$
    – AnalogKid
    Commented Jan 30, 2023 at 16:40
  • \$\begingroup\$ The components shown do not match with the LM311. Please show the actual circuit that you are using. \$\endgroup\$
    – RussellH
    Commented Jan 30, 2023 at 19:27


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.