Let's Make Robots!

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.

Speaker Noise

Greetings fellows,

Still plugging away on my big project. All goes well, except my 8ohm speaker is giving off a trememdous amount of noise while it's on. It works fine, but there is always a high-pitched "white" noise.

In addition, my project uses small servos, and i've noticed a "click" sound come out of the speaker whenever I turn the servo off (low 1). I assume the problems are related.

Is there too much power going to the speaker? Do I need some sort of voltage regulation or supressive diodes or who knows what?


This thing is insane. 25 servos. I can't imagine the resources put into this thing.

Has anyone heard of, or used, Phoenix code?

Update 3/27: Per request, I've attached the code I used for this guy. -------------------------------- This is my next little object-avoider, made from spare parts … Read more

IR module circuit

Howdy all.

Has anybody connected their picaxe to a RadioShack 276-640? Its the IR reciever module you can pick up at any store ... and the only one I have access to.

I set it up with the same circuit shown in JKlug's walkthrough, but no lcuk


...Progress for an un-submitted robot project......

This is a BIG project for me. 4 servos, 2 wheels, 4 LDR sensors, 4 tactile switches, IR tracker, 2 power supplies, IR remote control, and a speakjet, all rolled into one bot. It's been fun, but one challenge after another. This blog is to show my progress before I submit the actual robot entry.

.....LED Pain.............