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  1. chopnhack

    More efficient LDR "dark" switch?

    I thought there might be another way, but I had an old dmm with that feature - one was at 327, the other was 331. I should say that is pretty close! So transistors working, but something else is a miss...
  2. chopnhack

    More efficient LDR "dark" switch?

    Going back to your very detailed troubleshooting Hop Yes, the voltage divider circuit portion is working correctly - voltage swings from 0-2.7vdc with both pots. Not quite 3v (the battery still tests out at a little over 3v, but it might be some draw from the breadboard??) We get no light at...
  3. chopnhack

    More efficient LDR "dark" switch?

    The above is what I am working with currently. Unfortunately the spice model is showing 0.8mA across the LED whether R3 (LDR) is light 2.5k or dark 25k. I don't think the pot is being simulated faithfully, so the above is just a reference for the physical model on my breadboard. That is a very...
  4. chopnhack

    More efficient LDR "dark" switch?

  5. chopnhack

    More efficient LDR "dark" switch?

    I have to run to work - I appreciate your efforts. I will redraw the schematic to reflect what I am working with to be clear. I was just copying and pasting Colin's to keep close as a reference while I worked on all the suggestions you guys have made. The last thing I checked was part two of...
  6. chopnhack

    More efficient LDR "dark" switch?

    Ok, repeating these instructions with the LDR removed - I get a correct voltage divider - each pot 100k and 500k give 0-2.9v swings. I must have miswired the first run.
  7. chopnhack

    More efficient LDR "dark" switch?

    The 1M resistor was replaced with a 10k resistor (brown-black-black-red - I write this to check myself, Adam not you - I am befuddled by a simple analog voltage divider right now! :mad::oops:) The LDR is in place and the pot is a 104 100k with center tap between LDR and 100k resistor. 100k...
  8. chopnhack

    More efficient LDR "dark" switch?

    I forgot!! I had swapped the 100k out with a 10k yesterday when I was fiddling with it - sorry about that :oops::eek::D
  9. chopnhack

    More efficient LDR "dark" switch?

    Hi Adam - not directly, it goes through the LDR first.
  10. chopnhack

    More efficient LDR "dark" switch?

    0.4v-1.7v with 100k pot - checked the resistance of the pot and it seems to be fine sweeping from 1.4-ohm to 10k - wierd 0.22mV-2.95v with 500k pot
  11. chopnhack

    More efficient LDR "dark" switch?

    Wouldn't this indicate that to accomplish what I am trying to do is mathematically impossible with the existing circuit? With the LDR in, there is no response from the circuit - same current usage with LDR covered or illuminated. LOL, yes, but I think this is more achievable for me right now.
  12. chopnhack

    More efficient LDR "dark" switch?

    I had been doing this since the circuit was not providing much current to the LED, but good point!! New Tagline <<Hop - keeping the lights on, one LED at a time>> ;-) With LDR out and 100k pot - circuit does not work. With 500k pot, it does work and rotates through 23.3uA to 0 with accompanied...
  13. chopnhack

    More efficient LDR "dark" switch?

    Thanks Adam - I would like to try getting post 23 working, but that was strictly from my brain and certainly no guarantee that it is sound :D:eek::p As for Colin's circuit: I gave it another go: The only changes were: 100k pot changed to a 500k pot because the first test with 100k didnt...
  14. chopnhack

    More efficient LDR "dark" switch?

    I am sure its just my misunderstanding, but the circuit Harald posted shows a 555 being used for its hysteresis for the LDR to cleanly operate. I need the IC for its timer function, I don't think it can do double duty and I can't use two in this design. The 7556 is a possibility but it doubles...
  15. chopnhack

    More efficient LDR "dark" switch?

    No worries Hop, enjoy your down time. I would say come back refreshed, but its looking like you will need a vacation upon your arrival - and you have all those goodies waiting to go when you get back, LOL. Pace yourself, please ;-) Who, knows, with any luck and much help from the members here, I...
  16. chopnhack

    Differences between LTSpice and Real circuit and why?

    Harald had mentioned the Schmitt trigger as well as comparator but I was trying to avoid many more components. I thought I could simply arrange the LDR to give me an on/off, but as he explained there won't be a clean on off unless the Scmitt trigger is used. I need to work on this some more. I...
  17. chopnhack

    Differences between LTSpice and Real circuit and why?

    I will review the datasheet and see if that reset pin can be tapped. The pin is kept high currently. What do you mean by an LDR power switch? This is the current LDR switch I have been working on. Ammeter in series between the battery and circuit shows 3.4mA Through LED 0.22mA.
  18. chopnhack

    Differences between LTSpice and Real circuit and why?

    Turn the circuit on and off. Off when light and on when dark.
  19. chopnhack

    Differences between LTSpice and Real circuit and why?

    The current real circuit is using green, I assume at around 2.2Vf. The transistors - well, I was just messing around with them to see if I could get them to function the way I was thinking they would. In this case, I was thinking to save power in the system. Instead of relying on the 555 to...
  20. chopnhack

    Differences between LTSpice and Real circuit and why?

    Do you think 100k resistor is too high to saturate the base? I am trying to limit the current to the base to the least allowable. While playing with spice, I went up as high as 20MΩ before I started to see a drop in current across the LED. At 100k resistance to the base, the base current on...
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