Let's Make Robots!

LED Pain

Hey All,

Conventions for Naming

Not that this is a particuliarly important discussion, but ...

Is there a logic behind the naming of different bot versions in an upgrade? For example, what makes a robot become 2.0 versus 1.2? Is there an actual standard somewhere?

And is a robot's version based on software? Hardware? Either/Or?

That's all. Go.


Has anyone had any success programming the event phrases into the SpeakJet's EEPROM? I don't know if this is done via a PIC or right from my computer. The software implies that you load it onto the speakjet directly from the computer, but how would I do that? 

LED String

Hey All,

Let me present my next round of noob question to keep you all on your toes....

I'm trying to add AmandaLDR to my next project. Two eyes in front, two on the bottom for edge detection. The problem is that digital outs and space for wires are limited, so I was hoping to combine my SuperBright LEDs into a single output if at all possible.

When I connected the anode of one LED to the cathode of the next LED, only the second LED would work. Ditto for the third of 3, etc.

1. Is that because of the forward voltage of the LEDs?

Boosting Speakers with the Lm386

Hey All,

So I'm integrating the SpeakJet into my next project, and using the LM386 to try to boost the speakers. Unfortunately, the package didn't include any circuit (or information whatsoever, really) and Radio Shack has discontinued their databooks. So I went to the go-to info tool, THE GOOGLE! I've seen this circuit all over the place:


A few questions about this circuit:

1. Is the .05uf cap and 10 resistor recessary if it's just going to ground?

motor driver idea

Hey all,

I'm trying to create a bot that uses a lot of forward/backward motor action, and I'm hoping to make a low-power, small, lightwieght motor control using switch transistors. However, my electronics experience is -5. I came up with this idea that seems simple and effective, but I'm sure there's something I don't understand about the process. So with that in mind, here's my ultra-simple H-bridge.


Sintra / expanded PVC

Hey all you users of expanded PVC:

I just got a nice big piece of sintra for my next project. Very cool stuff. Light, durable, and best of all, FREE!!! (got it from the showroom of a local plastic supply).

So before I go ahead and ruin it, let me throw out some questions to those who have used it:

1. What do you use to glue it? Super Glue? Plastic bond? Pipe glue?

2. What about cutting it? Jig-saw? Dremel?

3. Has anybody tried molding/bending/shaping it?

Crystal Oscillator

Hello to my fellow robojunkies!

I'm trying my hand at building my own circuit for my next project, and I've finally (I hope) picked up all the parts I need, but I've got a question. The part SAYS it's right, but it's so much bigger than the one on the project board.





Resistance and Ohm's law with Leds

Okay, this question is based on OddBot's great build your own ir sensor tutorial.

I noticed that the schematics showed a 150R resistor inline for the 2 IRs, but 82r for the single version.

My understanding of Ohm's law is that if I increase resistance, I decrease current. Therefore, wouldn't I want less resistance for the 2 leds?

Or am I missing an important part of the equation? Is the transistor increasing current, and so more resistance = more voltage?

the schematic:

Boosting speakers

Once again, I beseech the robot gods for some info ...

Speakers: How can I boost the sound/tune command from a picaxe to a speaker?

I've got a small 8ohm speaker that I've used in the past, and it works great (as long as the motors aren't droping the voltage) but  I want to boost my output. I've also got a much bigger 1 watt speaker I want to use. How would I boost it?