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  1. foTONICS

    logic probe

    i see what you mean now about the supply rail voltage. I reworked the biasing so I could dump the third ground wire and now the low won't trigger, the output stays off regardless of it's input
  2. foTONICS

    logic probe

    to get the cct working correctly I had to add a third wire as a ground so I could properly bias the reference terminals
  3. foTONICS

    logic probe

    built circuit Hey man thanks a ton for the help, I've attached some photos of the circuit as well as some operating pics of the hi and low states. You mentioned not to use the 741 but I had already built the circuit at that point. it seems to be working correctly but am I endangering the...
  4. foTONICS

    logic probe

    C1 is a smoothing cap right?
  5. foTONICS

    logic probe

    Would a LM741 be a suitable replacement? It's the only op amp I have on hand
  6. foTONICS

    logic probe

    so with nothing touching the probe tip the negative input of UA1 is at 2.5V If the tip touches a logic high of 5V what does this do to the reference voltage of UA1, does it add to it? I've tried searching these schematics online before but get confused when I start thinking of what voltage...
  7. foTONICS

    logic probe

    so I just want a basic logic probe, red = LOW & green = HIGH. I don't care for frequencies just those two basic needs although I am putting some rules down for my project. Mainly when I'm not touching anything I don't want either of the two LED's to turn on. Attached is my idea. The probe...
  8. foTONICS

    irregular tigger pulse why?

    I'm not sure the answer to your questions about triggering but this guy does great videos on oscilloscopes and analyzers
  9. foTONICS

    controlling lights

    frequency reactive lights
  10. foTONICS

    irregular tigger pulse why?

    Maybe it's data being transferred, like this http://en.wikipedia.org/wiki/Manchester_code
  11. foTONICS

    controlling lights

    Hey all, I've been kicking around several ideas for having music influence 3 sets of lights ( low, medium, and highs). at first i was using sallen key active filters but just thought of something. i remember in my telecomm class we talked about tank circuits and how we can pull AM/FM signals...
  12. foTONICS

    lights synchronized with music

    circuit Just realized I never attached the drawing of the up to date circuit In the test run I removed the cap between the audio and ground in addition to the connection between pins 1 & 5 and ground
  13. foTONICS

    lights synchronized with music

    frequency response graph So I cleaned up the circuits a little, added some values to the components and gave it a test run. At first I had pins 1 & 5 tied to ground but for some reason that was causing a lot of heat to build up in the LM741. So I just left them open and tried again. Attached...
  14. foTONICS

    RS-232/TTL encoder

    Hey all, I have a DTE/DCE board which takes a TTL signal from one end and translates it to a RS-232 signal (-15/+15 out of phase signal). These boards are already made, I'm just testing them to make sure they are still functional. I have a Tektronix osciliscope monitoring the TTL signal...
  15. foTONICS

    lights synchronized with music

    update so i changed this into a sallen key configuration. it mentioned that the knee is reduced but my question is by how much, is it a huge difference? I have attached a picture with the new circuit, i havent changed the values to achieve the frequencies I talked about earlier, I just...
  16. foTONICS

    lights synchronized with music

    I put a cap on the audio in just to keep the dc out, is that part necessary? and although i do want a little bleeding into the the next band when i tested this it was going all the way into 4kHz
  17. foTONICS

    lights synchronized with music

    now at the right where it says 'relay' may not necessarily be a relay but just something to manipulate the light
  18. foTONICS

    lights synchronized with music

    So I'm trying to develop a circuit that will allow LED's to turn on and off depending on what the frequency is. I have decided to split the circuit into three parts; the first one detecting anything from 0hz - 2kHz; the second stage detecting 2kHz - 6kHz; and the last stage detecting anything...
  19. foTONICS

    LM741

    go figure i would find something right after i post this I found a LM148JAN. I assume if I only use 2 of the filters I should ground all other inputs?
  20. foTONICS

    LM741

    I am designing a cascading low pass filter to stop frequencies around the 2kHz band. I don't mind if the filter response bleeds into the 3kHz band but I would like to make sure it doesn't go any further. Right now I'm using two LM741's but wondered if there were already IC's that had multiple...
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