Let's Make Robots!

IR phototransistor

Hey LMR:

Has anyone used these?


Calculon picked up a bunch for cheap, but hasna figured out how to work it. His is an l7819, though. He's wired it up like so:


Which doesn't show any kind of result. Any ideas?

Before you ask: yes, calculon is a friend of the Google :>

splitting voltage

Greetings Earthlings,

Calculon's current project involves 2 12v motors (he's in the big-time now :)) but he'll probably have to use an 18v battery. He wonders what is the best way to power the brains AND the wheels from this.

Should he use a 12v voltage regulator and a 6v regulator at the same time? Or is there a better way to divide up the voltage?

xmos progess anyone?

Calculon recieved a note from his lovely postman indicating that he will get it on monday. :)

From what he's been able to read, he gets the impression that almost all mechanics/electronics (motor control, LED control, adc, sensor-type switches, and so on) must be handled by other ICs that communicate to/from the xmos board with serial ...

Is that right, or is there something he doesn't understand yet?

Anyone used a camera via microcontroller?

Hey All,

Calculon wonders if anyone has used a digital camera and been able to send the image as data? (serial or i2c)? Basically, Calculon wants a bot to send pictures to his PC/Webserver without having to get involved. Is this sort of thing possible with Arduino? Or perhaps XMOS?



Arduino and Serial communication

Hi All,

Calculon is thinking about jumping onto the Arduino bandwagon, but he has a question or two about serial communication:

- Can an Arduino talk to a picaxe via serial? Calculon understands that picaxe signals are inverted, while Arduino's are "non-inverted"(whatever that is). Is there a way to reconcile this difference? An inverter or something?

- Do the Arduino boards such as the Duicimillanovaililuanne have outpins that can be used for serial communication?

Calculon OUT!

Big and Cheap motors in the US

Hey All,

Calculon is laying the groundwork for a new bot that is much bigger than his existing bots. He seeks input on where he can get cheap motors that operate in the neighborhood of 12 volts.

His priorities, in order, are:

-torque (30-40 lbs)


What do you guys recommend? Windshield wiper motors? Garage door openers? Power drill motors?

Transistor Confusion (again)

Greetings fellow meatbags.

Calculon is trying to hook up a pimpin motor to his Mr Basic, and has come across something very confusing with his transistor.

Here's what he's trying to do with a nte123 pulling a seperate power supply to a motor made for 3v:


He also tried it with a 2n3904. It didna work for either. According to his understanding of NPN transistors, the output from the picaxe should switch on the tran, and pull the 3v through the motor. No?

dumb question about capacitors

Hi all,

I recently added a 0.01uf capacitor across one of my ICs ("decoupling"). Thanks for the advice guys.

It works great at supressing electronic noise, but I don't understand HOW. It would seem to me that connecting the positive right to the negative would shut the whole thing down. But obviously it didn't. So what does a capacitor's uF value mean?

How much current is allowed to pass through it?

Or how much current it stores at any given time?

hacking toys

hey all,

i'm trying to take apart a bunch of toys and other small electronics. They all have a push-button that mashes down on the PCB to operate. the spot underneath the button looks like this: (forgive the hasty visual):delete-me.gif

I think that the push of the button connects the two. So my question, then:

What's the best way to get "electronic-ize" this so my IC can do it?


-solder them together and turn the power on/off via my IC?

darlington drivers

Hey all.

Calculon has a question about the uln2803 darlington driver. He has a datasheet that says "the darlington pairs may be connected in paralell for more current-carrying capacity."   Calculon wonders how this is done?

Would that be pair of darlington pairs? And if he wanted more current capacity than that, what transistors would he use to make his own d-pair?

Calculon thanks you.