November 2011

You are currently browsing the monthly archive for November 2011.

Here’s a video of my very hackable 12-channel logic level shifter/translator with a voltage regulator. This video demonstrates how it works. There’s more detail here at the DIY 12-Channel Bidirectional Logic Level Shifter post.

In this example, it’s translating from 7.5V to 3.3V. In another example at the link above, I’ve demonstrated the hackability by wiring it up to drive a 3.3V Nokia 5110 LCD, using five of the 12 channels as logic level translators. Channel two is wired directly to 3.3V for power, channel three is wired directly to ground, and the transistor on channel nine is turned so that the 5V signal controls the gate, which allows PWM control of the LED with full power from the regulator.

Music: “Art Now” by AlexBeroza (CC BY 3.0)

Share

40-pin female headers are inexpensive and easy to trim down to size, and with a dot of CA glue (super glue), you can even easily make other configurations, like 2×4. Sometimes they’re even described as “break-away” headers, although admittedly they don’t break away as easily as the male pin headers. Just keep in mind that if you don’t score it, it could shatter.

Someone was looking at one of my PCBs and commented that it’s “impossible to break them apart without destroying at least 2-3 pins each time.” Using this technique, I’ve never “destroyed” any more than one, and with a little care, the edges turn out quite nicely.

Music: “The New Music” by AlexBeroza (CC BY 3.0)

Share

He we’re test-driving the our latest robot creation for the first time. It’s the boy’s design and made mostly of wood. The tires are o-rings, and there’s a 12V AA batter pack sandwiched between the two pieces of plywood. The system right now consists of a drive controller using a Modern Device‘s RBBB (small Arduino-compatible) and the Pololu TB6612FNG Dual Motor Driver Carrier, a robot controller, which is a standard Arduino Uno (which doesn’t do a whole lot right now expect forward messages from the remote), and a remote controller, which is another RBBB, joystick and display.

Right now there are two driving modes. The first is a tank drive, where, for example, if the joystick is moved far left, the right wheel moves forward at full speed and the left week backward at full speed. The second mode is what I call “target drive,” in which you set the target speed and direction of each wheel. Soft starting and stopping is built in to the controller, and the jerkiness you see sometimes is a bug in the keep-alive timer — if the robot stops getting messages in target drive mode, then it will stop.

Music is “Don’t you”┬áby stefsax (CC BY 2.5).

Share