Hi all,

First of all thank you very much for accepting me in this great forum of electronics and circuits. I am a beginner in this world and would like support in developing a project that I have in mind and what I will explain.

I want to replace the normal 12v aquarium led switch ON(Blue + White) – OFF – (Blue) into a light sensor system. Imagine ON(Blue + White) during the morning until there is enough light, OFF during the day and ON(Blue) during the night. Can you help me out on what to buy and how to setup in order to accomplish this project?

Best regards

 

Hi John, welcome to the forums!

Yes such a device is possible, a light sensor can run two comparators to sense low light and lotsa light to turn on one or two transistors that run the lights. Since this runs off 12 volts DC it should be safe to experiment with.

First thing to find is a "light sensor." Google that and look for something that makes sense to you that is affordable and has a voltage output. It would be helpful to find one that runs off the same 12V.

Hook that up in your room and see if the voltage output (measured on a meter) gives useful levels when the light changes in the day.

Once you have that making the rest should be easy, though sensing light levels may prove to be tricky. A cloudy day may foul it up.

I hope you have a meter and a soldering iron to put some bits and pieces together.

Good luck!

 

You probably want to build this yourself, but in case you want to get going asap have a look at this $10 relay.
https://www.amazon.com/GERI-Control...1493823731&sr=8-1&keywords=light+sensor+relay

 

Hi John, welcome to the forums!

Yes such a device is possible, a light sensor can run two comparators to sense low light and lotsa light to turn on one or two transistors that run the lights. Since this runs off 12 volts DC it should be safe to experiment with.

First thing to find is a "light sensor." Google that and look for something that makes sense to you that is affordable and has a voltage output. It would be helpful to find one that runs off the same 12V.

Hook that up in your room and see if the voltage output (measured on a meter) gives useful levels when the light changes in the day.

Once you have that making the rest should be easy, though sensing light levels may prove to be tricky. A cloudy day may foul it up.

I hope you have a meter and a soldering iron to put some bits and pieces together.

Good luck!

Hi ErnieM,

Thanks for the advice, I already have done some investigation but I haven't found yet how to control the LDR in three stages. Which controller should I use in order to achieve this?

Best regards

 

You probably want to build this yourself, but in case you want to get going asap have a look at this $10 relay.
https://www.amazon.com/GERI-Control...1493823731&sr=8-1&keywords=light+sensor+relay

Hi Wingsy,

Thanks for the tip, however I want to control 3 stages with a single LDR (if possible!).

Best regards

 

There are a few possibilities. If you want to keep it just parts you can consider using several voltage comparator circuits. If you scroll down the link you will see some "Window Comparator" circuits. You would configure a LDR in a voltage divider circuit the output of which would drive three window comparator circuits and each comparator circuit would drive a LED network. The downside is a small pile of parts. Another option with a very low parts count would be the use of a uC (micro-controller). A single little 8 pin chip could likely be programmed to do it all with a few very basic lines of code. Just as an example a little PICAXE 08M cost about $3.00 US, they are easy to program and do not require much of a programming jig or fixture. Again the LDR is part of a voltage divider the output of which drives the uC Analog Input and three pins serve as outputs. There are a good number of uC boards out there as starter kits. The downside is you need to set up a jig to program the chip and do some very basic code. There are plenty of examples online. PICAXE is merely one of many examples. Arduino is another good contender for a uC with a wide range of possibilities.

Also I have seen this little board extensively. Spark Fun shows it as discontinued but other places show it in stock. Obviously availability of any components depends on your location. Three of those would be a sweet start.

Ron