This instructable is part of the one motor walker.

The bicore or suspended bicore is the name given to a little circuit created by Mark Tilden. He is the founder of BEAM robotics. BEAM robotics is an acronym for Biology, Electronics, Aesthetics, and Mechanics.


quote from Wiki http://en.wikipedia.org/wiki/Nv_network

"Probably the most utilized Nv Net topology in BEAM, the Bicore consists of two neurons placed in a loop that alternates current to the output. Input into the loop is given in the form of changing the resistance in each separate Neuron, which changes the rate at which the Neuron discharges, affecting the pace at which the loop oscilates."

WOW my head! Let me reformulate that for you.

The bicore is a oscillating circuit. In our case, it will oscillate a motor, like the wiper on your car.
The motor will go back and forth, back and forth when power is apply.

Look at this video to understand:


This instructable was a Flash animation for my BEAM website. You simply follow these instructions.

Step 1: The bicore freeform

Many thanks to Ian Bernstein from www.beam-online.com
100% nothings wrong checked it many times
<p>I Have followed the steps one by one and managed to make it BUT , when i connect it to 5v all i can see is that my motor is vibrating like crazy and after measuring the voltage across the motor i discovered it was less than a volt.....</p><p>I Used the 74HC240 , With the 22nF Capacitors and a 1/4 100k resistor , my motor is a dc one from a cd player . . . . I Am utterly confused, any help please ?</p>
oh boy oh boy! It's been a very long time I did not touch a bicore!<br><br>are you sure those are 22nF?<br>are you sure that is a 100k resistor?<br>is the motor able to spin easilly with a 5V battery?<br><br>If you change from 100k to 1Meg resistor, this will tell how long it turn on one side then the other side. On a servo motor it turn clockwise for 1/2 a second and anti clockwire for 1/2 second<br><br>if you have a small resistor, that mean that it would oscillate really fast..<br>maybe that is why you hear the vibration but it might just be the motor spinning clockwire then anti clockwire REALLY fast.<br><br>try a different resistor,<br><br>measuting the motor voltage could and could not be usefull.<br>I guest that if the oscillation is slow, you might actually see for example 5Volts for 1/2 second then -5Volts for 1/2 seconds.<br><br>if that does not work, disconnect everything and star again.<br>try on breaboard. try other small motor.<br><br>oh yeah... the HC240 is not that powerfull... you need the AC that can provide more current per pins. Yeah HC = 35mA per output<br><br>the AC = 75mA<br><br>you have 3 buffer/output on the bicore, that mean<br>35mA * 3 = 105mA<br>75mA * 3 = 225mA<br><br>Now it depends on how much current your motor is. If it's brand new and not recycle it can be low, under 100mA otherwise if it's more then it could not work since the chip will protect itself or fail.<br><br>good luck!
Well , I don't know I am starting to feel dumb , I made the whole thing again only to get the same humming motor , the difference is when I push the motor it starts moving indefinitely to one direction , for the love of god I can't find a AC version
Thanks for your fast response , you provided me with all the stuff I should know, Appreciated ! :)
I created a similar machine and I used an AE-MDL-DualusDC chip. The chip allows you to get 1A RMS, 2A peak, per H Bridge and its really small. Both sides of the chip allow you to control the power and control signals. If you need to solder your own wires on it has SMT pads as well. Here&rsquo;s more info about the chip http://www.avayanelectronics.com/Products/AE-DualusDC/AE_DualusDC_Manual.pdf . I found some really cheap ones at DriverDudes.com, you can get just the board or have it fully assembled. Here&rsquo;s the link to DriverDudes http://driverdudes.com/product_info.php?products_id=32
hi. im wondering if the capacitor value is essential? can i use a 0.1 microfarad ceramic cap instead of 0.22??
no programming or software?
If i am using a 9v battery which Chip should I use instead of 74AC240.
hey guys.<br>i got the ic 74hct240.<br>What i was wondering is that does this ic require any sort of programming or is it pre programed..<br>thanks..<br>wicked.sunny.89@gmail.com<br>
Hello Sir, Can I use 'SN74LS240N' instead of 74HCT240. I am unable get this IC . Please tell sir,I really want to do this project. Also is their any application of '74HC14B1' IC in BEAM Robotics.
Why is pin number 16 connected to pin number 17?!
you got it wrong, that is pin 3 and 4, the chip is upside down. It connected like that because that is the way to make the bicore work. Look up the schematic of the bicore.
I have constructed the bicore circuit. Now I have modify the servo. However I want to know why the servo was chosen over a simple DC motor. And what is the drive current and the sink current of the circuit?
simple DC motor does not have a gear box, that mean no power to make the robot walk. Each inverter from the smith trigger can deliver 24mA. I think we have 3 gates so that mean 72mA for one direction, then 72mA for the other direction. A total of 144mA . That is the 74AC240 chip from fairchild. It could change depending of the manufacturer.
I don't understand. So what if it doesn't have a gearbox. Can I not just glue a circular piece of plastic to the shaft of the motor which will do the same thing as the servo horn and then glue the gear which has been cut in half to that plastic piece?<br>Also, if I'm using the servo I don't have to remove the plastic tab right? And is 6V input to the terminal okay? Because it says 5V in the bicore tutorial.
I have made my BICORE.But it is not working.Does the difference in motor cause that.I live in India so can be?the poblem is-it's taking only one round and stoping,don't know why?I have a 9V battery so can that be the problem.i have many questions to ask so please don't be annoid.Please.
Hello, I believe the 74AC240 can only handle 6v max so chances are you've blown the chip. With my playing around with freeforming ive found it usefull to freeform an IC holder as that way any damaged ICs can easily be replaced.
http://www.fairchildsemi.com/ds/74/74AC240.pdf page 2 absolute max rating is 7V, the recommended is 2 to 6V
Hello again,Jerome i have another problem-i have a resistor of some other colour so that could be the prob?only two colours are matching.
&nbsp;Hey I bought a cool BEAM robot like this at<br /> <br /> &nbsp;<a href="http://www.middlecreekmerchants.etsy.com" rel="nofollow">www.middlecreekmerchants.etsy.com</a><br />
pl help me . i ve finished making d body of d walker . m not getting d control circuit output for two days . pl help me out .<br />
hi . m not getting any rotation of shaft after i did this circuit . any suggestionms ?
hello robomaniac, <br />I cant get the 74HCT240, does it have to be a particular kind of IC chip?<br />can you suggest me another IC chip?<br />thanks
yes it has to be a 74xx240 chip<br />the xx mean HCT, AC, etc.<br /><br />If that was not a specific IC it would be call &quot;theUniversalChip, you can use it everywhere&quot; it does not exist... microcontroller can do sort of that.<br /><br />There are is a lot of chip and they all do different things in life.<br /><br /><br />you can buy it online here www.solarbotics.com<br />
I've built a two motor walker before, and discovered and built yours many years back! I loved the simplicity of it, why make a master slave using two motors! Anywho I rediscovered your tut here on instructables and I have to say great graphics and I'm excited to try again. I've always wanted to try using a pager motor and cell phone lion battery (with the possibility of a solar charger as a separate project). Think it's possible?
If you use a pager motor, you need a gearbox. You can also use lithium battery but be sure to have the specific charger for those battery. Maxim IC have chips for USB lithium battery charging. And yes you could make a robot using those item. Have fun! Jerome
Would an internal gearing system like this be powerful enough?<br/><a rel="nofollow" href="http://www.hobbyengineering.com/H1705.html">http://www.hobbyengineering.com/H1705.html</a><br/>Or<br/><a rel="nofollow" href="http://www.hobbyengineering.com/H2341.html">http://www.hobbyengineering.com/H2341.html</a><br/>Thanks again,<br/>~Ryan<br/>
The pager size motor gear box is not enough powerful.<br/><br/>The second motor is perfect.<br/><br/>Check there<br/><a rel="nofollow" href="http://www.solarbotics.com/motors_accessories/gear_motors/">http://www.solarbotics.com/motors_accessories/gear_motors/</a><br/>
i must be getting on your nerves now, huh? take it as a compliment. does it have to be a particular kind of IC chip? i have a MAW2819.4. will this do? it's 20 pin.
you are not getting on my nerves.<br/><br/><strong>Does it have to be a particular kind of IC chip</strong><br/>If I ask you this &quot; do you think manufacturer make 1 single 20 pin chip for the entire world?&quot; The ultimate universal chip that fits in your ipod, your cell phone, pace maker, airplane, watch, etc.<br/><br/>The answer is no, I could not even google the chip number you have.There are millions of chip out there and each and single one has a specific function.<br/><br/>So no, not all 20 pin will do.<br/>
hmmm. bugger. well, this one came from a remote control, so i'll give it a go. i'll have a look at the robot the control went with too.
Question: Do I use a solar cell or batteries? If I do connect a solar panel to it, how do I know that I won't FRY the IC.
This circuit can only be powered by batteries. Connect the circuit to 5V and you will not fry it. Instead of connecting a motor, you can also plug 2 LED at the output ( where the motor was connected) to see if the circuit works. Connect the Anode to the chip and the cathode to ground. Same thing with the other LED on the other side of the chip.
Thank you, I just was wondering
Hey there is an error in the connections...pin no. 17 and 16 are shown to be connected when they are actually not! In other words we are practically connecting i/p of one not gate to o/p of another...thus creating a monostable multivibrator...
Parts list and links to purchase parts would help greatly. Presentation is great, but lack of info kills it.
I will take that in concideration for my next instructables, I am making soon. check out www.solarbotics.com for parts, they have everything for that project. Thanks Jerome
Nice write up... Just to point out for others that may not be aware... Windshield wiper motors do not reverse directions - they spin in one direction and drive a mechanism that has the back and forth motion....
they are so powerfull...
Hey om im a 12 year old guy and i was wondering what parts do you need for all this and can you get them cheap i am working my way up to bigger robots i started with bristle bot then almost done with your beetle bot and my next project is the walker, also i have a schematic for a robot i invented i was wondering if you could help me out with it but you dont have to thanks!
very interesting! gratz there

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Bio: I am a French Canadian that loves robots and embedded electronics. I work on all kinds of cool projects, like a high-power electric push scooter ... More »
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