Back to Basics: Ohms Law

During last night’s Open Hack Night, while trying to explain things like how transistors and mosfets work, it was discussed that maybe taking a step back and outlining some of the basics of electronics would be beneficial to everyone. So I decided to start with Ohms Law.

There are 3 things that Ohms Law deals with, and they are all related to each other. Those things are Voltage, Current and Resistance.

Voltage is measured in… well Volts of course!

Current is measured in Amperes.

Resistance is measured in Ohms! Named after this guy who put a bunch of work in discovering resistive properties electricity, and apparently came up with this relationship known as Ohms Law. Anyhoo.

I like analogy’s to help me relate things that I know, against things I don’t know. So everyone’s favorite analogy of electricity is water. Some will argue this topic to death, but for my purpose I’m sticking to it.

Voltage — So Voltage is actually a potential concept, think of a large water tank on the top of a hill and a small pipe coming out of the bottom. The difference between what is coming out of the pipe versus the pressure in the tank is the potential voltage. So voltage is the pressure.

Current — This would be the volume of water pushed through that pipe by the voltage (pressure) and would refer to the quantity of water flowing through it.

Resistance — So this would be the pipe its self. The larger the pipe (lower resistance), the easier current can flow through, thus having more current. The smaller the pipe (higher resistance), the harder it is for the current to flow through the pipe, yielding less water.

Open House Party

We’re really excited to announce that Baltimore Hackerspace has moved to a new location and we would like you to come help us celebrate. Come socialize, learn and check out the facility. We will have our projects on display and will be doing a couple workshops. There is also a rumor that there may be food!

If you are attending I invite you to RSVP so we can get an idea of how many people are coming.

http://www.meetup.com/Baltimore-Hackerspace/events/89508782/

When: November 17th, 2012
Time: Noon – whenever
Where: 6410 Landay Ave. Baltimore MD 21237 MAP

Class – Getting Bootstrapped with Git and GitHub

*** UPDATE ** This event has been canceled. Sorry everyone. We’ll be having Open Hack night instead.

Interested in getting started with Git? Curious about what’s so great about this DVCS stuff? Have no idea was DVCS is? Join us for an awesome night of Git and GitHub and get bootstrapped. Jared from GitHub (@ShepBook) will be presenting and will be hanging around to answer your questions!

Wed, November 7th, 2012. 7:00 pm.

Limited space available, so please register at http://www.meetup.com/Baltimore-Hackerspace/events/88080042/

We built, We raced, We lost

It took a lot of hard work to get the kart ready in time for the PPPRS event at Maker Faire NYC 2012. But we made it!

Needless to say, we learned a lot. Mainly to get started a little earlier — and not wait until 2am the night before to get the kart moving.

Burnt Mosfets, burnt motors and broken wheels later we made it back home to ponder the next one. Here’s a video showing some of the races, we had fun.

The road to PPPRS: a light at the end of the tunnel

Last night was a good night for kart construction. we got a tie rod stretched between the wheels. it is just a bunch of allthread with some dethreaded sections on the end. these dethreaded sections make it easier to adjust, since we can just chuck it up in a drill and spin the rod rapidly to get it on or off the car. It works well enough to connect the two sides together, but needs some tweaking. Tie rod ends are nuts welded to coupling nuts.

Also related to steering (and throttle, and brakes), someone at the space had the bright idea to cannibalize a razor electric scooter which had a throttle grip, a brake lever, its own self-contained ball-bearing mount, and a telescoping/folding mechanism. This scooter was a dumpster find but can be found on craigslist for $50, and it also includes a battery, motor, motor controller, wheels, charger, etc which we didn’t use. I think next year we may see more of these used for steering because when we want to change drivers or if we get in a frontal collision, the steering system just sort of folds away from the driver without actually becoming disconnected. it’s perfect for us.

Perhaps most importantly, we got all our drive components finally. we were able to weld the motor mount pods onto the frame and get the motors hooked up. The pictures don’t show a whole lot, but that’s OK since the mounts need a bit of tweaking and reinforcing at this point anyway.

finally, we turned the original front bumper into a foot rest. we ran a piece of metal up through it to make it more robust, then welded that piece of metal to the frame.