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the LED itself turns on in the dark

May 9, 2010 Electronics / DIY electronics 154 915 13

We need the following components:

one LTR-4206E phototransistor

one lithium CR2032 battery (3 V)

2N3904 transistor

1K resistor

Photos of these components:

Working process:

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

Next, solder a phototransistor to this design:

Next, we attach the LED:

And then the power source:

And now we look at what we got:

This light will turn on when it gets dark

come back

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Comments (13)

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

cool !!
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#2 Dimonio Guests April 22, 2011 10:07
0

Dear, you didn’t draw the diagram correctly. You are applying "+" power to the BASE !!!! (average conclusion according to the scheme) And in the pictures correctly (To the collector). Correct.
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#3 Dimonio Guests April 22, 2011 10:08
1

Firstly, the scheme will not work, and secondly, FT will bark as soon as it opens, because everything will go directly to it :))))
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#4 yomko Guests March 17, 2012 16:42
0

and just such a photoresistor?
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#5 yomko Guests March 17, 2012 16:49
0

Sorry, not a photoresistor, but a phototransistor? : feel:
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#6 ilan Guests June 11, 2012 18:46
0

and if there are 6 diodes at the same time, then what should change in this circuit?
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#7 hrustal Guests September 28, 2013 13:43
0

Super! Thank you very much, this material is what is needed to implement my idea.
I’m also looking for a solution for such an idea: I need an autonomous mini-backlight with a switch. Well here is a mini, as in your example with a photo-LED. Maybe you have such an operating time: an autonomous mini-backlight based on an LED with a switch (with position fixation). As an option, one could use a finger-type mini-flashlight, but I have not seen any with a switch that fixes its position))
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#8 Lar_draco Guests October 11, 2013 17:06
1

my light was dim
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#9 Dinar Guests November 5, 2013 13:14
0

But can I connect to 12 volts?
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#10 Belek Guests November 20, 2013 13:16
0

my light was dim
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#11 Egor Guests November 20, 2013 15:48
0

And in what way does it turn on in the dark?
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#12 Alexander Guests August 26, 2014 14:46
3

You can find such a phototransistor in FIG. Can't you replace it with another?
- To answer
#13 yurka Guests January 26, 2015 20:40
0

will a phototransistor go out of the mouse? Or do you need a photo-LED?
- To answer