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Solar powered nocturnal personal fan

Solar powered nocturnal personal fan
A small fan, driven by a hobby motor. Powered by 2x AA rechargeable batteries. The batteries are hooked up to a solar panel, which recharges them during the day.
The circuit is switched by a CdS cell (light switch) which means the fan switches on when it is dark enough, at night, hopefully.
Only after I'd built the (incredibly ugly - sorry, no photos available) prototype did I realise I could've bought a pesonal fan for $5 and hacked it instead.
Here's the schematic. Feel free to use it or improve upon it to your own satisfaction.
 
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Step 1Parts, clarification, that is.

The transistor is an ordinary NPN 100mA 45V.
The CdS I hacked from a solar garden light.
The solar panel came from the same place.
It's output is (rough estimate) 4.5V, 60mA.
I used an old hobby motor with a range of 2-6 volts. No special reason, it was handy. And the propellor came from a model plane.
That leaves the diode, 1N4004, and the two resistors, 1k and 10k.


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9 comments
Jul 27, 2011. 4:49 PMgaby1st says:
Hi there,
I have a question here what is the meaning of LDR.Thanks u.
Apr 9, 2011. 8:19 PMaccount3r2 says:
Could you swap the light sensor with a switch?
May 12, 2009. 6:24 AMTheYetti says:
I don't really understand are these just the Blueprints for the fan..?
Apr 28, 2009. 2:23 AMLosenger says:
What's the purpose of the 1K resistor? It will work just fine without it. Change the 10K fixed resistor to a potentiometer to be able to adjust the point at which the transistor turns on. Swap the positions of the 10K and photo-resistor to create a "light on" switch. Also, the diode doesn't have to be a 1N4004. Any 1N400x series diode will suffice.
May 10, 2009. 12:18 PMn0ukf says:
Or if you give it a thermistor, you can have a temperature controlled fan.
Aug 24, 2008. 12:05 AMYerboogieman says:
whats the input into the fan; voltage?
May 10, 2009. 12:14 PMn0ukf says:
To the motor? Two NiCd cells @ 1.2V each, 2.4V.
Jan 24, 2009. 3:30 PMrevhead says:
I used a similar circuit in my rechargeable battery powered laser for an alarm system.

you can check my Instructable out to see how you can even further enhance this circuit at:

http://www.instructables.com/id/Laser_Beam_Alarm_System_with_Rechargeable_Battery_/
Apr 12, 2008. 3:15 PMawkrin says:
I guess no one will do this thing on a pcb, but just in case, here's a pic generated from croc tech 3d I edited it a little to make it more clear...

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Author:Wonko the sane