Hackerspace Garage Sale & Lightning Talks – Saturday 11/16

This Saturday, we’ll be doing a new kind of event: A garage sale. We’ll be selling stuff in the space now and letting our members come in and sell their interesting stuff. For example, we have a bunch of servers, workstations, ham radio equipment, odd electronics, monitors, etc etc. We really don’t know how much stuff we’ll have to get rid of.

The point of the event is to raise money for Interlock so things being sold by the hackerspace go back into keeping the space going, and expanding its facilities. We are accepting donations for items that you find around the space.

The second part of this event is that starting at 7:00pm, we’ll be doing lightning talks. You can come for the sales, but stay for the presentations. Lightning talks are 5-10 minute presentations from people all over the community about nerdy subjects that interest them. If you have something you’d like to share, come in and show us!

We’ll also be giving you food that our members have made you.

So TL;DR:

  • Garage sale 5:00pm
  • Lightning Talks 7:00pm
  • Food and drinks served
  • Outsiders welcome
  • Help us raise money and clean up the space!

Flyer_garage_sale

 

from on November 12th, 2013Comments0 Comments

Rochester Academy of Science: 40th Annual Fall Scientific Paper Session

The Rochester Academy of Science holds its 40th Annual Fall Scientific Paper Session, consisting of short talks, posters, and a keynote talk, all today at Nazareth College.

Subjects include chemistry and biochemistry, cell biology, physics, zoology, evolution and paleontology, astronomy, archaeology, education, pedagogy, ecology, with Roger Easton of RIT presenting the keynote, Imaging technologies and the Impending New Golden Age in Manuscript Studies, all detailed in the full program.

Registration for lunch closed November 4, but the the sessions are open to the public and there’s still time to catch some of the posters and the keynote.

from on November 9th, 2013Comments0 Comments

Motor Controller Mini-workshop – Applying PWM for Speed Control

Last Tuesday we had a mini workshop on controlling DC brushed motors using an Arduino.  We covered controlling the speed and direction of a DC motor (in both directions) using an H-bridge. Some important take-aways from this are:

  • The motor cannot be connected directly to the Arduino, motors typically require more current and voltage.  The ATmega328 (the chip inside the Arduino) can handle a maximum of 40mA of current.  Motors (even small ones) pull 100mA to 10′s or 100A.  If this much current was pulled from the processor it would likely blow up the output port.
  • Approximated to the first order, the speed of a motor is porportional to the voltage applied to the motor.
    • This is a very first-order approximation, the speed will change when a load is applied to the resistance drops in the drive circuitry and the motor.
  • Approximated to the first order, the load on the motor (how hard it is pushing against a load), is proportional to the current through the motor.
  • In order to change the voltage on the motor, a voltage is switched on/off quickly at a certian duty cycle (on some of the time, off the other).  This is known as PWM (pulse-width modulation)
  • On an arduino, the PWM functions are called using the functions “analogWrite”

Example code from the class is:

 void setup() {                
   // initialize the digital pin as an output.
   pinMode(3, OUTPUT);
   pinMode(5, OUTPUT);  
 }
 // the loop routine runs over and over again forever:
 void loop() {
   digitalWrite(3, LOW);   // turn the LED on (HIGH is the voltage level)
   analogWrite(5, 200);
   delay(5000);               // wait for a second
   digitalWrite(5, LOW);    // turn the LED off by making the voltage LOW
   analogWrite(3, 200);
   delay(5000);               // wait for a second
 }

PDF Presentation: Controlling_DC_Brushed_Motors_Using_Arduino

Schematic of the circuit we breadboarded: Motor_workshop_1_Schemtic

from on November 2nd, 2013Comments0 Comments