How to freeform the bicore ( BEAM robotics )

This instructable is part of the one motor walker.
http://www.instructables.com/id/How-to-build-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.

http://en.wikipedia.org/wiki/BEAM_robotics

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:

http://www.solarbotics.net/bftgu/starting_nvnet_bicore.html

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

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Step 1: The bicore freeform

Many thanks to Ian Bernstein from www.beam-online.com

MCRIPPPer says: Jun 17, 2011. 6:31 PM

hi. im wondering if the capacitor value is essential? can i use a 0.1 microfarad ceramic cap instead of 0.22??

lukeD says: Jun 5, 2011. 10:55 AM

no programming or software?

saqrock says: Apr 21, 2011. 10:06 PM

If i am using a 9v battery which Chip should I use instead of 74AC240.

101nemesis says: Feb 2, 2011. 10:08 PM

hey guys.
i got the ic 74hct240.
What i was wondering is that does this ic require any sort of programming or is it pre programed..
thanks..
wicked.sunny.89@gmail.com

yogesh99 says: Sep 28, 2010. 11:46 AM

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.

PrathameshKini says: Sep 11, 2010. 10:10 PM

Why is pin number 16 connected to pin number 17?!

robomaniac (author) in reply to PrathameshKiniSep 12, 2010. 2:00 AM

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.

PrathameshKini says: Sep 10, 2010. 10:05 PM

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?

robomaniac (author) in reply to PrathameshKiniSep 10, 2010. 11:37 PM

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.

PrathameshKini in reply to robomaniacSep 11, 2010. 12:52 AM

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?
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.

aviksaras says: Jul 4, 2010. 5:05 AM

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.

mattyh in reply to aviksarasJul 17, 2010. 3:37 AM

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.

robomaniac (author) in reply to mattyhJul 17, 2010. 8:24 AM

http://www.fairchildsemi.com/ds/74/74AC240.pdf page 2 absolute max rating is 7V, the recommended is 2 to 6V

aviksaras says: Jul 4, 2010. 5:09 AM

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.

salahaddam says: Jan 9, 2010. 5:01 PM

Hey I bought a cool BEAM robot like this at

www.middlecreekmerchants.etsy.com

mohankarthik says: Dec 9, 2009. 8:57 AM

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 .

mohankarthik says: Dec 9, 2009. 8:55 AM

hi . m not getting any rotation of shaft after i did this circuit . any suggestionms ?

cheverecachaimachochidoche says: Oct 7, 2009. 9:33 AM

hello robomaniac,
I cant get the 74HCT240, does it have to be a particular kind of IC chip?
can you suggest me another IC chip?
thanks

robomaniac (author) in reply to cheverecachaimachochidocheOct 7, 2009. 10:43 AM

yes it has to be a 74xx240 chip
the xx mean HCT, AC, etc.

If that was not a specific IC it would be call "theUniversalChip, you can use it everywhere" it does not exist... microcontroller can do sort of that.

There are is a lot of chip and they all do different things in life.

you can buy it online here www.solarbotics.com

warpling says: Sep 1, 2009. 3:02 PM

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?

robomaniac (author) in reply to warplingSep 1, 2009. 3:09 PM

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

warpling in reply to robomaniacSep 1, 2009. 6:35 PM

Would an internal gearing system like this be powerful enough?
http://www.hobbyengineering.com/H1705.html
Or
http://www.hobbyengineering.com/H2341.html
Thanks again,
~Ryan

robomaniac (author) in reply to warplingSep 2, 2009. 7:44 AM

The pager size motor gear box is not enough powerful.

The second motor is perfect.

Check there
http://www.solarbotics.com/motors_accessories/gear_motors/

derbert says: Aug 3, 2009. 4:20 AM

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.

robomaniac (author) in reply to derbertAug 3, 2009. 5:46 AM

you are not getting on my nerves.

Does it have to be a particular kind of IC chip
If I ask you this " do you think manufacturer make 1 single 20 pin chip for the entire world?" The ultimate universal chip that fits in your ipod, your cell phone, pace maker, airplane, watch, etc.

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.

So no, not all 20 pin will do.

derbert in reply to robomaniacAug 3, 2009. 6:29 AM

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.

derbert in reply to robomaniacAug 3, 2009. 6:06 AM

(removed by author or community request)

derbert in reply to derbertAug 3, 2009. 6:12 AM

if my capacitors are .22uf but are the black tube ones does THAT matter?

Ghost Wolf says: Jul 18, 2009. 10:31 AM

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.

robomaniac (author) in reply to Ghost WolfJul 18, 2009. 11:32 AM

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.

Ghost Wolf in reply to robomaniacJul 18, 2009. 2:01 PM

Thank you, I just was wondering

Yashknowsbetter says: Apr 2, 2009. 11:03 AM

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...

m3lt says: Feb 21, 2009. 10:19 PM

Parts list and links to purchase parts would help greatly. Presentation is great, but lack of info kills it.

robomaniac (author) in reply to m3ltFeb 22, 2009. 12:47 PM

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

105

trebuchet03 says: Jul 15, 2008. 6:02 PM

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....

amando96 in reply to trebuchet03Feb 21, 2009. 7:35 AM

they are so powerfull...

robomaniac (author) in reply to trebuchet03Jul 17, 2008. 1:20 PM

Thanks!

allenph79 says: Jan 19, 2009. 7:45 AM

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!