Update; My age category for the contest is 13-18 because I am fifteen. :)
Yes, the title explains it pretty well. In this Instructable I will show you step by step how to construct a light sensitive, solar powered, robot. All you need is some parts that can easily be found in the trash or in your backyard. I built mine totally from trash.
Yes, the title explains it pretty well. In this Instructable I will show you step by step how to construct a light sensitive, solar powered, robot. All you need is some parts that can easily be found in the trash or in your backyard. I built mine totally from trash.
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Signing UpStep 1: Bits and Pieces
Parts...
2- 1.5 volt motors
1- AAA battery pack that holds 2 batteries
1- On/Off switch
1- Old solar powered garden light
Random bits of wire
zip ties
And something to use as the chassis for your robot, I used some bits of Erector Set parts, but almost anything can be used.
Tools...
Needle nose pliers
Wire stripper
Screwdriver
Scissors or wire cutters
A vice grip (optional)
Magnifying glass (optional)
Soldering iron and solder (not optional)
Glue gun and glue
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This should be an excellent project for a 7th grader!
cool robot, love the tripod
very original
martzsam,
Cool project, but I don't quite understand what is going on.
Do the batteries need to be charged to get the 'nominal' motion and the extra light on the cell adds the additional power to increase its speed?
Said another way, without the batteries does the robot move in the light but only at 1/2 speed?
Or is the extra light only hitting the light sensor and that's what's increasing the speed of the bot? (This wouldn't make sense because the light sensor is supposed to turn off the device when it gets too light)
Did you have to do something to the light sensor since normally the light sensor turn off the power to the circuit when it is sensing light since this function is to turn on the 'load' when it gets dark? Said another way does the robot stop moving in bright light?
Are the batteries wired in parallel or serial? If serial then I wouldn't think that they were being charged at all since the circuit would be designed to charge a single cell and would not provide sufficient voltage to charge two cells.
It would be nice if the robot would continue to charge the battreries when switched off. Have you cheked that there is no current going to the betteries when the switch is in the off position? Without knowing the circuit design we really aren't sure what's going on in it, like it operation in the off position, how the light sensor works, or if the battery charging circuit has over charging protection.
Thanks for posting the project matrzan! I really light the idea!
Best Wishes
1. The robot doesn't work without the batteries, I worked it so the robot starts with a full charge, then maintains that charge with the panel while it is running. The solar panel does not directly power the motors. It like just adding on another battery that never dies in parallel.
2. The batteries are wired so their gross output is only 1.2 volts, not 2.4. This allows for the 3 volt soar panel to do its job charging them even in low light. In other words, yes they are wired in parallel. (which is probably important and I should update that...)
3. There is absolutely no current going to the batteries when the switch is off because the switch is right on the positive out from the pack.
4. And when you said,
"Or is the extra light only hitting the light sensor and that's what's increasing the speed of the bot? (This wouldn't make sense because the light sensor is supposed to turn off the device when it gets too light)"
you are totally correct, because the panel doesn't power the motors directly, the circuit relies on the light sensor to tell it when to speed up or slow down.
I really hope that made sense.
Can you explain why the light sensor speeds up the motors? Do the motors simply replace each LED (and one motor explicitly does so, if I read it right, I guess the other one to)? One would expect the motors to slow down when the light hits the sensor. Or am I missing some alterations to the to the garden light's circuit?
A garden light' s circuit normally contains some kind of joule thief circuit to drive the LED(s) from a single 1.2 V battery, with an extra to have darkness switch it on.
Maybe the light sensor influences the balance between voltage and current? When dark: high voltage, low current needed for a LED, when light: low voltage, LED doesn't work, but higher current possible.
LEDs cut off below a certain voltage, no matter the current, while motors are strongly controlled by current. Of course motors are at the same time controlled by voltage, but I expect the garden light circuit to provide a rather low current (designed for LEDS), making this current the limiting factor.
Does this make sense?
Thank you for putting a video I would have been screaming for one