1. CWNC Trojanators Electrical Basics
09/28/2016

2. Electrical 101
Types of Electrical Current Delivery in Circuits and Loads AC
Wall power in USA: 120VAC
High Voltage Power Transmission: 100,000 Volts
Current “alternates” in the wire- it literally changes direction periodically
Examples of AC signals: Electric Guitar; the pickup responds to vibrating string by producing an AC voltage

3. Electrical 101
Types of Electrical Current Delivery in Circuits and Loads DC
Car Battery: 12VDC, AA Battery: 1.5VDC, Modern iPhone/ Android Battery: 3.7VDC
Microelectronics: Microcontrollers, Transistors, etc. typically 3.3VDC to 5VDC

4. Electrical 101
Battery Symbol

5. Resistance
Just like a skinny vs fat garden hose will change the RATE of water flowing out of it for a given water pressure, we can change the amount of current along a circuit by adding a RESISTANCE factor. This component is called a RESISTOR
SYMBOL
UNIT: OHMS (after German physicist Georg Simon Ohm
Ohm’s Law: VOLTAGE = CURRENT * RESISTANCE
Voltage is like a pressure, think of a water tank connected to a hose handle

6. Voltage and pressure

7. Voltage Divider
I need to track a 12VDC battery voltage on an analog pin on a microcontroller. I am trying to see what the current level the battery is. The microcontroller has a maximum rated input of 5VDC. How can I go from 48VDC to 5VDC so I don’t blow up the microcontroller?
Voltage Divider: a simple way to shift the voltage from one level to another
Need to watch the load current because if it’s too high, the output of the voltage divide will SAG, which is a technical term for dropout, lower, cut out, drag, dip…

8. Voltage Divider Solution
Atmel ATMEGA328 (popular on Arduino boards) has an input resistance of at least 10Kohms DC.
We can set R2 to 1,000 ohms. This will not “load” the output voltage considerably
Knowns: Vin, R2, Vout.
Rearrange the equation and solve for R1
R1 = R2 (Vin – Vout) / Vout
R1 = 1,400 Ohms.
Total Resistance from 12VDC to “ground” = 1, ,000 = 2,400 Ohms
Total power loss = Pwatts = V^2 /R = 12*12 / 2,400 = 0.06 watts = 60 mWatts
Total current in resistors from V = I*R; Solve for I;
I = V/R = 12 / 2,400 = AMPS, = 5 milliAmps

9. DC Resistance per FOOT, Copper

10. NICE CHASSIS WIRING

11. UGLY CHASSIS WIRING

12. COMPONENTS
The RoboRIO is the brain of your robot. The RoboRIO breaks out all of the connections you will need to operate your robot with and gives you the option of programming your robot in three different languages, Java, C++, and LabView. The RoboRIO specifications are as follows: Xilinx z-7020 CPU with a Dual Core ARM Cortex A-9 processor and FPGA combination
256MB DDR3 RAM
512MB nonvolatile storage(for programs)
2 Host USB ports (For cameras and other external USB hardware)
1 10/100BaseT Ethernet connection(for robot communication)
Up to 8 Analog Inputs(4 on Analog In Header/ 4 on Expansion Port)
2 Analog Outputs(on the Expansion Port)
Up to 16 Digital IO ports(10 on DIO Header/ 6 on Expansion Port)
10 Pulse Width Modulation(PWM) Ports(for motor control)
4 Relay Ports(for directional motor control)
Other communication types available including RS232, I2C, SPI, and CAN