LED turns on automatically in the dark

We need the following components:

one LTR-4206E phototransistor
one lithium CR2032 battery (3 V)
2N3904 transistor
1K resistor

Photos of these components:



Progress:
First, take a Transistor and a resistor and solder them as shown in the figure:



Next, we solder a phototransistor to this structure:



Next we will attach Light-emitting diode :


And then the power source:



And now let's see what we got:



This light will turn on when it gets dark



come back
Comment
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5+two=
Comments (14)
  1. serj
    #1 serj Guests February 9, 2011 11:56
    1
    Cool !! smile
  2. Dimonio
    #2 Dimonio Guests April 22, 2011 10:07
    1
    Dear, you didn’t draw the diagram correctly. You supply "+" power to the BASE!!!! (average output according to the diagram) And in the photos it is correct (To the collector). Correct it.
  3. Dimonio
    #3 Dimonio Guests April 22, 2011 10:08
    1
    Firstly, the scheme will not work, and secondly, the FT will bark as soon as it opens, because all the power will go directly to it :))))
  4. yomko
    #4 yomko Guests 17 March 2012 16:42
    0
    Is it necessary to have just such a photoresistor?
  5. yomko
    #5 yomko Guests 17 March 2012 16:49
    0
    Sorry, not a photoresistor, but a phototransistor? :feel:
  6. iLan
    #6 iLan Guests 11 June 2012 18:46
    1
    and if there are 6 diodes at the same time, then what should change in this circuit?
  7. crystal
    #7 crystal Guests 28 September 2013 13:43
    0
    Super! Thank you very much, this material is what I need to realize my idea.
    I’m also looking for a solution to this idea: I need an autonomous mini-light with a switch. Well, here’s a mini one, like in your example with a photo-LED. Maybe you have such experience: autonomous mini-illumination based LED with switch (with position fixation). Alternatively, you could use a mini-flashlight, but I haven’t seen one with a switch that locks its position))
  8. Lar_Draco
    #8 Lar_Draco Guests 11 October 2013 17:06
    1
    my light was weak
  9. Dinar
    #9 Dinar Guests 5 November 2013 13:14
    0
    can you connect it to 12 volts?
  10. Belek
    #10 Belek Guests 20 November 2013 13:16
    0
    my light was weak