Let's Make Robots!

Basic 74AC240 Bicore

reacts to light

Here he is, after three hours of soldering. His brain is the exact one from the "Junkbots, Bugbots, and Bots on Wheels" book. He's still a work in progress, and I still want to add some indicator LEDs and some solar cells so he can charge a battery. Also, I'm really new to this stuff, and I would appreciate any tips and/or constructive criticism and/or ideas.  His body was from a kit called a brush bot that I modded a little with a dremel tool.

A good view of his brain:

A view of his bicore brain

An even better view of his brain:

A really zoomed in view of his brain

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I have a 7805.  I think that might work.

cool bot, btw, what does it do? you should edit it with a lot of information, and that googly eyes, such a nice addition :D


the thing about the googly eyes is this: he was originally something called a brush bot.  it's a kit that lets you make an extremely simple robot that, at its heart, is a motor, switch and batteries.  he vibrates on a brush, and as the bristles vibrate with the motor, he moves.  He had googly eyes that came with him.  Anyway, he was on my bench and I was looking for a motor for the bicore I was making.  So some hot glue and solder later, and here he is now.

Answering your first question, he follows light.

I don't get it. How do you make a single motor bristlebot follow light?

Hi, Ignoblegnome. After you posed the question, a thought occured to me as to how it could be accomplished.

First I would curve the ends of all the bristles towards the rear.

[Added: I forgot to mention that the long axis of the brush are the right and left ends, while the narrow /short axis is front and rear; thus some might consider this bristlebot would go "sideways".]

Might need to heat the bristles slightly to get a permanent bend. The vibration would then be set to be front to back and the curved bristles would tend to make it always go forwards. [--remember I said that is the short axis of the brush.]

Now while you would only need one motor in this plan, you would still need 2 sensors.

The 2 light sensors will be used to control which direction the motor turns. [a comparator op-amp or transistor amp, or a microcontroller will be needed to do this.]

 I don't recall where at the moment, but I have seen a gear arrangement where the motor turns a secondary gear which is mounted with its axle in a slot (which is roughly twice the height of the gear teeth). When the motor turns one direction, the gear is pushed to one end of the slot and engages a tertiary gear which would be linked to a vibrating cam to vibrate one end of the brush (for this example, the right hand end). If the motor turns the opposite direction, the secondary gear slides to the other end of the slot and engages a different tertiary gear which is linked to vibrate the other end of the brush (the left hand end in this example).

Vibrating one end will make that end tend to creep forward, while the other stands still. So if the left hand sensor gets more light, then the motor will turn in the direction that makes the right hand end creep forward, and vice versa. Thus you get motion and steering in one brush. The brush will "follow" the light.

I can picture it in my mind; hope I described it well enough to get the point across.


For the sensors, you mean something like a photodiode, or do you mean an LDR?  I am on a super limited budget.

Actually, either would work in the right circuit. That is the thing about this hobby; there are many ways to do things. You can work with whatever is in your budget.

If you add back to back photodiodes to the BiCore in a suspended fashon you can achieve headbot type behavior or at the very least, light response. You can scavange photodiodes from technoscrap.


I know you can get them from mice...