Let's Make Robots!

MOSFET vs BJT

Hi guys. I have to admit i do not know much about these kinds of transistors... i mean, their difference.

I have to get a large current pass through a wire, but after having read articles on wikipedia about mosfet i don't really know why i see them on, say, motor drivers instead of BJT transistors. One thing i don't know about is whether you can find logic-level high-power BJTs but i know there are logic-level FETs, like the IRLD series. But again, if you want to switch a BJT on fully then maybe you could just arrange them into a Darlington i guess.

Why am I an idiot and IR transistors...

Here's the encoder part http://www.sparkfun.com/datasheets/Sensors/QRB1114.pdf

 

This should be simple... resistor pulls the input pin high, transistor clicks and pulls it to ground.

What am I missing?!?!?

 

Walter_Autodrive_007.jpg

Animatronic NIN

Uh, yeah. Nothing like taking a happy fun memory and turning it to Nine Inch Nails :

FYI, the Rockafire Explosion was an animatronic band that played in a kids pizza chain, Showbiz Pizza, in the 80s. Kooky, happy, family songs, played Beatles Happy Birthday song for kids, etc. Now only in collectors and inventors hands. 

And now, after the Showbiz's have closed, this.  Wonder if they'll cover Pantera?

UART level translation, what type of translation IC is required?

I have two devices, and need to figure out how to translate between them for 2 wire UART.

U-Blox NEO-5G, 1.8V
Input low:  0.22V (MAX)
Input high: 0.91V (MIN)
Output low:  0.4V (MAX)
Output high: 1.4V (MIN)

Telit GC864
Input low:  0 - 0.5V
Input high: 2.1 - 3.3V
Output low:   0 - 0.35V
Output high: 2.2 - 3.0V

UBlox -> Telit
LOW: .4V (MAX) -> 0-0.5V   (WORKS)
HIGH: 1.4V (MIN) -> 2.1-3.3V (DOES NOT WORK)

Tips for making a robot multi-task

I have a robot, and my robot has a brain. However, my robot's brain can only think about one thing at a time. I can set I/O pins high or low, and they will stay there until I change them, but that isn't going to work. Here's the deal:

Oh_Oh Robots

 

Hello Everyone. This is a news flash from Mexico. David Cuartielles is now  here spending the summer in Mexico, given workshops about creating small robots. The Oh_Oh robot was introduced at the Faro de Oriente. This small bot is
commissioned by the Spaniard Cultural Centre and The Faro de Oriente. This bot is an open source  project created by Cuartielles and Yang from the Physical Prototyping Laboratory from the University of Malmo, Sweden.

Here you can see a few pictures of the bots. Cool, aren´t they?

Bring Back the Challenges

As you all looked at LMRs home ribbon some new things have been added. However, SOMETHING IS MISSING. take a guess. If you guess challenges you are correct. What ever happened to that? Why did they take it away? Who knows. I think the challenged brung out the true creativity that makes this sight AMAZING! Sure the prizes where nice, but nothing beat the thrill of either winning or judging other peoples robots. Should they bring the challenges back? Give me your thoughts.

FIXED: irin resets servo?

I've attached an IR receiver to a servo to use as an IR beacon detector. I'm trying to have the servo sweep through its travel to look for an infrared signal using the "irin" command on a 28X2. I want it to start the servo all the way to the right and pause for an IR signal check. If no signal then increment to the left a little bit, look for IR signal, if no signal, blah blah blah...

My (original) code snippet:


let servo_pos = 70

Arduino, holding wires in without soldering?

So I am building/ working on my robot, http://letsmakerobots.com/node/24204 and I didn't want to solder the wires into my arduino. Whenever I moved robot, the wires come out of the pins. Currently I am using scotch tape, I know not very professional. I was wondering if there is any other way to keep the wires from coming out?

 

Thanks

 

Walter Needs a Mouth

We did this once with walter's old "eyes", now another round of brainstorming with his "mouth".

Walter needs a mouth. In the past I have used the "picaxe sound detector circuit"  modified a bit, going to a few blue LEDs. As a track was played (assume the track is speech) the leds would blink and change intensity according to the audio levels. This was ok, I guess... I think I might want to go to a "led bar-graph chip" with say, 8 to 10 segments. As he speaks, the bars could be lit --from the center -->out and with more bars showing as audio levels increase. I dunno.

simple sound detection - headphone level input

So I have found a few different sound detection circuits, but they usually integrate a mic and an amplifier circuit. I want to make a circuit that takes in headphone or line level audio via 3.5mm jack that will close a relay when a sound is coming through the input. From what I understand headphone and line level audio has more power than mic level audio signals. The audio signal does not have to continue on to a speaker or anything after going through the circuit, and doesn't have to sound like anything in particular (can just be a series of tones and quiet periods) 

Arduino code question and problem.

Can anyone help me to take a look of the code following? CODE 1 works fine to have motor runs forward and backward:

Really small RF receiver

hey guys,

so i am building a really small robot( 25 X 25 X 10 mm) and i want it to be remote control. I wanted it to be controlled by IR initially but i found that IR cannot work in direct sunlight so i thought i need an RF unit. Do you guys know of any really small RF receivers. I was thinking of those used in real cars for door unlocking. What do you guys think??

start here robot ultrasonic sensor

Newbie here

Hi every one i have been member for a while now and have finally collected all the parts needed to complete fritz start here robot.

Every thing is the same apart from im using a 28x2 picaxe instead of the 28x1 picaxe,also using the ultrasonic sensor pictured below (in attachments instead of the SRF05.

i have followed the walk  through on http://letsmakerobots.com/node/66  for the SRF05 sensor and translated the wires to my sensor as followed:

SparkFun: According to Pete

I found this series of videos by Pete from SparkFun.