How to Build a DIY Fully Automated Light Controlled Fan Regulator
The Life of an electronics repair engineer is not always about repairing something that is broken. Or about something that needs to be replaced to fix a device. Sometimes it is also about fixing a problem by designing something that still even doesn’t exist. This article is an example of such an enterprise. This project can also be used as a great example how to design something before even building it.
This little project shows in some detail how you can design and also simulate your circuit on your pc before you grab your solder iron. This article explains how to build a DIY “Fully automated Light controlled Fan regulator”.
It all began about 4 years ago when my brother asked me to help him in making a Fully automated Fan for his Toilet. He already had placed the 240V AC Fan in the Ceiling and an electrical power socket next to it on the wall. So that was handy to place my Fan controller in later on. My brother had previously placed a Manual controlled switch in the Fan power cord but wanted to eliminate the need to do it by hand everytime you left the toilet. And even often forgot to switch off the Fan after a while.
So I checked the internet and couldn’t find any suitable working circuit that also was cheap and easy to Build. So I decided to design one myself. I saw some circuits on the internet that used a NE555 ic but they all didn’t work! But I adapted the idea of a NE555 in my circuit because it is easily useable as a fantastic time delayed switch. And they almost cost close to nothing.
I used an older dated version of Tina (v8) which I used to develop and simulate this project. For this circuit probably every Trial version will work.
Because my brothers little Toilet room is rather dark, everyone always uses the Light switch when he visits it. So it only was logical to use an LDR as detector to know if and when the Toilet was occupied or not. And I found an empty Power adapter that I choose to build my Fan controller circuit in to. The open position that used to be for the Voltage Selector was ideal to place the LDR behind. (Of course with a little transparent protection window of some plexiglas in front of it afterwards. To prevent that someone could be able to get in contact with the dangerous 230 V AC if he would try to touch the LDR. And I made sure that it also was not possible to touch any of the other parts in the Adapter). Because it all has to fit in the Adapter case we can’t use a transformer, so we use a special X2 ~250V 0.47uF Capacitor with a 9Volt zener and some diodes and a few extra capacitors.
The two wires (Brown and Green) coming out of the Power adapter are the wires for the already placed FAN. And the 230 VAC Plug in the re-used Power adapter for this project, plugs easily into the Electrical Power Socket on the wall right under the Ceiling were the Fan is placed.
And when the Power adapter was placed, the LDR would look in the direction of the Light Bulb in the Toilet room. Light Bulb on means that the Toilet was occupied and the LDR value would show a Low Resistance value. Only when one would leave the Toilet the Fan should start to turn. There are commercially circuits but they all use one of the Switch wires of the Toilet Light Switch.
My circuit would not need this extra signal wire because it would work Fully Optical. Sort of wireless in a way and therefor simpler and better! No need to reroute the existing wires in your Toilet.
The photo below shows the final product with the LDR looking out of an old Power adapter.
Before I show the final working Circuit I will show all made project photos of the Ready Working Adapter. Keep in mind that the bottom pcb really looks a bit chaotic but that is only because I made my circuit on the original rearranged Power Adapter pcb. And I made another little pcb on top of that, so that it still fitted in the original Power Adapter housing.
Also don’t let the way my project looks in any way make you disapprove of how I built it because it already worked for over 3 years or more now without any problem whatsoever!!
So I am really proud on this result! And I hope that it will convince the reader to try to develop something from scratch also with the help of Programs like Tina. There also is a Tina v.9 Free version ,obtainable on the Internet as a Texas Instruments (TI) version.
Above: Don’t let Looks deceive you. This could be a commercially designed Project of which this was the Prototype ! (That already works for about 3 years now without any trouble at all!)
Above: Showing more clearly the special x2 250V Capacitor that replaces using a transformer.
Above: LDR with NE555 chip in socket and with TRIAC on Alu Cooler. Safety Fuse on other side.
Above photo shows the blue potentiometer that adjusts the LDR sensibility.
Above: View on top mounted PCB that holds the Transistors and the TimeDelay Variable Pot.
The Green Capacitor is a special x2 250VAC Safety Capacitor used to deliver the current for this “Automated Light Controlled Fan Controller”. Do not use anything less to prevent Fire or Short Currents. The max. provided current can easily be calculated out of Xc = 1/(2 x Pi x Freq in Hz x C).
And Finally here comes the Circuit that is Easily Build and working Great!
Note: Click on the above schematic to view in larger size.
Here is the list of the components:
Hope you all liked it !
Albert van Bemmelen, The Netherlands.
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You may also check his previous article in the below link: