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Would it be that easy?

stefan-xpStefan-Xp wrote 11/27/2014 at 21:01 • 2 min read • Like

Hmm.. sometimes the simplest solution is the best solution. But i have a disbelief, that it can be that easy.

The Task is: If The Supply Voltage is above a certain level AND the Light Level is below a certain level, light up a LED or an other load.

Theory of Operation: If the level at Pin 3 of the LM324 is higher than 0.7V (Diode Voltage) Output at Pin 1 will raise to V+. If the Level at Pin 6 is lower than the Level of Pin 5 the Output at Pin 7 will drop to GND. If those two conditions are true, the Optocoupler will get conductive ant LED1 will light up. The Parts are not the final decision, i just took some from the EAGLE Library ;-)



Here you find the Schematic:

and a board proposal:

What do you think? Will it work as desired?

UPDATE 18.12.14: Yepp it is :-)

With a few small changes it works as desired :) I'm very pleased by this outcome.

I think I'm using it soon in a Project with the ATMEGA Hearth :)

Unfortunately I'm going to use a bread board for the build (due to money and equippement), but with the Layout above it will not be that hard :) (But there is always place to improve :))

Comments are as alway very appreciated ;)

Update 16.02.2015: I've built the circuit on perfboard :) But not sure if i can show it off ;-P


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davedarko wrote 12/18/2014 at 23:53 point
I guess you've meant perfboard instead of a breadboard? ;) Which part of this project would you use with your atmega boards, when an ADC enables you to read out an LDR as well? You wouldn't need the comparator.

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Stefan-Xp wrote 12/19/2014 at 20:46 point
You are right! I always mix up those... Well i thought the Advantage would be, that the current consumtion would be much less (My power Supply doesn't show any, can't measure it better) with this schematic. Also the Analog Voltage Comparation will not differ as much as a A/D Value. Perhapps it would be better suited for other Applications without µC.

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Stefan-Xp wrote 12/18/2014 at 21:09 point
(y)

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