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Recent content by jptrsn

  1. J

    dark sensor circuit

    I breadboarded circuit 3A from the pdf you linked for me, and it seems to work well switching the relay without any unnecessary parts. I'm fairly sure that the relay is a 5 volt relay, because I pulled it off a board with a 7805 power supply. I'm not certain about the current requirements -...
  2. J

    dark sensor circuit

    Thanks for the great resource on photodiodes! I'm going to use one of the example circuits as a component in my overall circuit (the one displayed in figure 3b). I'm not sure what parts in my bin have a schmitt trigger (if any). The rapid switching isn't really necessary, but the hysteresis...
  3. J

    dark sensor circuit

    So now that I've learned all this, I'm going to redesign the circuit from scratch, and forget about the 4066 (since it can't do what I was hoping it was doing in the first place!) Perhaps the trouble I'm having is due to the analog nature of the 4066 (which I hadn't realized). Sorry for the...
  4. J

    dark sensor circuit

    I was using the 4066 to get the hysteresis I was after; I tried it out with only the transistor, and it did not give me a good on/off output - the relay wouldn't come on fully, or switch off clearly with direct changes of light input. Would I be able to eliminate the 4066, and maybe use a...
  5. J

    dark sensor circuit

    Hmmm. No problem to throw a transistor in to power the relay. Good point about th fuse, too. Does the protecting diode get reverse-biased across the relay's power terminals? I had intended R1 to pull up the 4066 input high when the photodiode PD1 is not conducting - Q1 is supposed to work as...
  6. J

    dark sensor circuit

    Hi everyone, A project I'm working on needs to have a circuit that will, when powered up, take input from a light sensor, and switch a relay once the light has dropped below a certain threshold. I've come up with a schematic diagram of what I think will work, and preliminary work on a...
  7. J

    Photodetector - what kind?

    Hi everyone, This is my first post, and I'm completely self-taught what I know about electronics. I'm trying to create a dark-sensing circuit using spare parts that I've collected, and I'm wondering about some of the parts I pulled out of a scroll-wheel mouse. There is a small slotted disk...
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