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

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Comments (14)

#1 serj Guests February 9, 2011 11:56
1

Cool !!
- Answer
#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.
- Answer
#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 :))))
- Answer
#4 yomko Guests 17 March 2012 16:42
0

Is it necessary to have just such a photoresistor?
- Answer
#5 yomko Guests 17 March 2012 16:49
0

Sorry, not a photoresistor, but a phototransistor? :feel:
- Answer
#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?
- Answer
#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))
- Answer
#8 Lar_Draco Guests 11 October 2013 17:06
1

my light was weak
- Answer
#9 Dinar Guests 5 November 2013 13:14
0

can you connect it to 12 volts?
- Answer
#10 Belek Guests 20 November 2013 13:16
0

my light was weak
- Answer