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- Circuits -

Note: All of the circuits on this page are for Personal use only. Commercial usage is prohibited unless arrangements are made with the patent holder Mark W. Tilden mwtilden@lanl.gov.

Printable quick reference guide

Solar engines - SE's are small circuits that gather energy from the sun, store it in a capacitor, and then release the energy to drive a motor, coil, another circuit.... Note that the 1381 and FLED SE's can only drive a motor or coil.
1381 SE - One of the more popular SE's because it's simple and easy to build.
FLED SE - If you can't find the 1381 voltage detector in your area try this SE. It uses a much more common FLED.
D1 SE - Charges all day, runs at night. Think noctibot here.
PM1 SE - This circuit it like the 1381 SE except you can run not just motors and coils. Use it for just about anything.

Photovores - A photovore is a robot that moves towards the brightest source of light, or if it's solar powered, food.

Photopopper - The photopopper is the most common solar powered photovore.
iVore - The iVore is great because it's VERY easy to build and tracks the light perfectly. A favorite when I'm doing demos.
BEAMant - A bicore controlled photovore. Works good but doesn't track very well in low light.

Bicore circuits - The bicore is the foundation for allot of BEAM robots. It's just a simple oscillator but when grouped together can produce complex behaviors.

Suspended bicore - Basic bicore.
Light seeking head - The motor "neck" turns the electronics "head" to look at the brightest source of light.

Walker circuits - A few complete designs I've put together.

CW1 - Simple to build and has a reversing sensor so when your walker bumps into an object it will respond and backup.
CW2 - Slightly more complex than CW1 and will make your walker turn when it encounters an object.
CW3 -Same as CW2 except that it will backup and then turn after bumping an object.
CW4 - A basic four motor walker utilizing a dual CW1 circuit architecture.

Motor drivers - All the walker designs above require motor drivers. A motor driver basically can take a weak signal from an input and amplify it. H-bridge - A good but slightly complex motor driver.

ALS245 driver - Simple design.
Servo driver - This circuit will allow you to drive standard hobby servos without the need to modify them.

Sensor circuits - Sensors and circuits to add to your bots to make them more adaptable or just plain cool.

240 Signal inverting circuit - AKA: Reverser. This circuit is used to make walkers backup and on four motor designs, turn.
IR object detector - A cool circuit that will enable your robot to detect an object before it even touches it. Other - Some other useful circuits that may not nesasarilly be used for BEAM. Battery Charger - Want to but a rechargeable batteries on your walker but need a way to charge them? Look no further.
FM radio transmitter - A simple circuit that could be used for say, a wireless mic.

1381 Solar Engine
Parts ------------------------------------------------------------- 3v+ Solar Cell Motor 2.2K Resister NPN 2N3904 Transistor PNP 2N3906 Transistor 2500uF to 10F Capacitor CMOS 1381J Voltage Detector
Notes: This is the most popular SE because of it's efficiency and reliability. It uses a 1381 Voltage Detector that can be found at Digi-Key in transistor and SMT packages. What this circuit does is..... 1. The solar cell starts charging the capacitor and the voltage rises 2. As soon as the capacitor reaches 2.7v the 1381 turns pin 1 high and turns the 3904 ON 3. When the 3904 turns on it brings the base of the 3906 low which turns it ON 4. With the 3906 ON current is supplied to the base of the 3904 which keeps it ON 5. Now current can flow through the motor and it turns 6. When the voltage gets down to .7v the transistors turn OFF and the process is repeated Check out some solarollers I've built with this circuit.
FLED Solar Engine
Parts -------------------------------------------------------------- Solar Cell 2500uF to 10F Capacitor NPN 2N3904 Transistor PNP 2N2906 Transistor FLED, Green, Flashing LED (aka; Blinking LED) 2.2K ohm Resister Motor
Notes: The FLED version of the SE is less efficient than the 1381 version. The operation is basically the same as the 1381 version, but uses a FLED instead of a 1381 Voltage Detector. Check out some solarollers I've built with this circuit.
PM1 Solar Engine
Parts ------------------------------------------------------------- Solar Cell 1N4001 Diode 3300uF-10F capacitor (C1) 2N7000 MOSFET 1381 J Voltage detector 47K ohm resister 2 - .47uF capacitors
Notes: This is an SE that can drive a bicore. Good for solar walkers, heads and more. For C1 I would recommend somewhere in the 4000uF range for a head and in the Farad range for a walker. If you would like to be able to control when your robot moves just put a switch across the source and drain of the 7000. Just make sure you turn the switch off when it runs out of juice or else it won't charge.
D1 Solar Engine
Parts ------------------------------------------------------------- Solar Cell 1N4001 Diode Large Capacitor (1F) or battery 2N7000 MOSFET 150K ohm Variable Resister
Notes: This is a neat circuit that comes alive when it gets dark. You can adjust the sensitivity using the 150K variable resister. The outputs can be connected to a LED bicore or whatever you want.
Suspended Bicore
Parts ------------------------------------------------------------- 74xxx240 2 - .22uF bi-polar caps ( 224 on cap ) 100K - 10M ohm resister Motor 3V
PCB layout on request
Notes: The resister goes between the two ®'s. You can see that only two of the inverters are used and the rest are used for upping the current so you can drive a motor directly. I do advise thou if you are going to drive a motor directly that you use the 74AC240 instead of the HCT. In order to drive a walker you'll need to know a little more about the bicore so check out the FAQ for more info. Another good application of the bicore is a head, read the FAQ for more info.
Photopopper
Parts ------------------------------------------------------------- Solar Cell 3300µF Cap 100K Variable Resister 2 - Motors 2 - Photo Diodes 2 - 2.2K Resisters 2 - CMOS 1381J Voltage Detectors 2 - NPN 2N3904 Transistor 2 - PNP 2N3906 Transistor 2 - .22µF Cap ( The number on the cap is 224 ) 2 - Tactile sensors 2 - 680K Resisters
Notes: This is the same circuit used in Solarbotics PhotoPopper Kit. It uses two photo diodes to detect and move towards the brightest source of light. If your bot moves too much to the right or left you can adjust the 100K pot. Check out some photovores I've built with this circuit.
H-Bridge
Parts ------------------------------------------------------------- 2 - 50K or higher resistors 4 - NPN 2N3904 Transistors 2 - PNP 2N3906 Transistors Motor
PCB layout on request
Here is the free form layout I use to free form my H-bridges. It's really easy and can be done in about 10 minutes depending on your skill level. All the pins are facing up. Click here for a page on how to freeform the h-bridge.
Reverser
Parts ------------------------------------------------------------- 74HCT240 2 - 1.6M resisters 2 - 30uF capacitors 2 - Tactile sensors 4 - 47K resisters
Notes: This is a very easy circuit to build and can give lots of functionality to your walker including reversing and turning. Check the FAQ for more info on incorporating this into your walker. If you need it to reverse you signal for a longer or shorter time replace the 30uF capacitor with a smaller value or larger value.
Phototropic Suspended Bicore
Parts ------------------------------------------------------------- 74xxx240 2 - .22uF bi-polar caps ( 224 on cap ) 2 - photodiodes Motor (geared) 3V
This is the circuit used for making a light seeking "head". You'll need to use a geared motor and a motor driver such as the h-bridge if your going to use it for a head. Pins are facing down.
The Almost
Complete Walker
Schematic
with reverser
Parts ------------------------------------------------------------- 74xxx240 4 - .22 uF bi-polar capacitors (Violet) 30 uF capacitor (Orange) 2 - 47K resistors (Green) 3 - 1.6M resistors (Red) 2.5M resistor (Blue) Motor drivers + Geared motors (M) Tactile Sensor 4.8v
Wow one of the few "complete" walker schematics on the net! This is a master/slave (two bicores, the slave syncs to the master to create a good walking motion) bicore setup with reverser. Look here to learn how to make a tactile sensor. You will need to replace the (M)'s with motor drivers and geared motors. An H-bridge works good as a motor driver and hobby servos work good for motors. Pins are facing up.
Battery Charger
Parts ------------------------------------------------------------- Battery Pack 100mA Wall transformer LED 10K resister 1N4001 Diode 1000uF capacitor
Notes: Make SURE all your polarities are right and there aren't any shorts before you plug it in. You'll need to find a wall transformer that has a current rating of around 100mA. Digi-key has one (Part# T206-ND) The best batteries i've found are cordless phone batteries and can be found almost anywhere. Possibly in your own home, just make sure your parents aren't watching. hehehehe

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Nervous nets copyright and patented by Mark Tilden. Content originally developed by Ian Bernstein.