Electricity and Circuits

Circuits and Wiring

Electricity and Circuits Spend time mastering and practicing the BASICS before moving on to more advanced concepts https://www.youtube.com/watch?v=8ve23i5k334&safe=active

Understanding Circuits: Batteries Chemical reactions inside the battery cause a build up of electrons at the anode. Electrons repel each other, so they will move to a place with fewer electrons in this case, the cathode! This movement of electrons is current, measured in amps (A). (The picture on the left depicts electron flow.)

Understanding Circuits: Batteries Possible activity with your students to help them understand batteries make a battery out of a lemon! https://www.youtube.com/ watch?v=dxir_orhoga&sa fe=active

Understanding Circuits Circuit: a complete and closed path or loop around which an electric current can flow Voltage: an electromotive force that is from the potential difference of charge between two points (measured in Volts, V) Current: a rate of change (or flow) of electric charge (measured in Amperes, A) Resistor: a component that limits or regulates the flow of electrical current in a circuit (resistance is measured in Ohms, Ω)

Understanding Circuits Battery Simple Circuit Diagram Resistor LED Bulb Switch Conductor

Understanding Circuits Circuit in Series Circuit Diagram

Understanding Circuits Circuit in Parallel Circuit Diagram

Understanding Circuits Comparing Circuits Series Parallel

Understanding Circuits Which circuit do we want? Series 12 V 3 V 3 V 3 V 3 V Parallel 12 V 12 V 12 V 12 V 12 V

Measuring Volts, Amps and Ohms Multimeters An electronic voltmeter, ohmmeter and ammeter all in one! Black lead ALWAYS goes here Red lead will change depending on what you are trying to measure

Measuring Volts, Amps and Ohms Once you select what you will be measuring, the ports will light up! Make sure to uncap the leads before inserting them into the ports

Measuring Volts The wavy solid line is ALTERNATING CURRENT. Make sure you select DIRECT CURRENT, which is signified by the dashed and solid straight lines. Red lead goes here

Measuring Volts In general, leads are placed in PARALLEL with the item being measured red to positive, black to negative Warning! If you measure voltage while set to amps, you can blow a fuse and ruin your meter!

Measuring Amps Select option depending on how many amps you are measuring Red lead goes here (unless you are measuring milliamps, but most of the time you will not need to)

Measuring Amps

Measuring Ohms There is only one option for ohms Red lead goes here

Measuring Ohms Measurements are made without power. If you need to measure an individual component, you may need to remove it from the circuit.

Practice makes perfect! Snap circuits Makey Makey Virtual circuits Conductive dough Everyday materials

Exploring Circuits Let s explore! Break into groups of 3 or 4 1. Light a bulb 2. Light two bulbs in two different ways 3. Make a circuit and light a bulb without using wire 4. Incorporate a switch 5. Make your own switch Pick one circuit to create a diagram for and use your multimeters!

Ohm s Law Ohm s Law states that the current through a conductor between two points is directly proportional to the potential difference across the two points V = I R V = A Ω Voltage (Volts) = Current (Amps) x Resistance (Ohms)

Using Ohm s Law What resistance does my LED require? To prevent the LED from blowing its fuse, the voltage and current needs to be decreased. Hypothetical Scenario: LED: Maximum of 3 V and 0.02 A (20 ma) Battery: 9 V How many volts need to be decreased from the circuit?

Using Ohm s Law What resistance does my LED require? The voltage needs to be decreased by about 6 V. Ohm s Law: V = IR R = V/I Therefore, R = 6 V 0.02 A R = 300 Ω

Using Ohm s Law How much voltage does a wire consume? Resistance is directly proportional to length and inversely proportional to cross-sectional area. R = ρ l A Where, R is resistance of wire (Ω) ρ is resistivity of material (Ωm) l is length of wire (m) A is cross-sectional area of wire (m 2 ) The longer and thinner the wire, the more resistance it has. This concept can be compared to water moving through a tube. You can measure the resistance of your tether and calculate the voltage drop.

Circuit Boards! MATE Circuit Board FRONT OF BOARD Made of fiberglass (insulator) Wired in PARALLEL Conductive wires and threads throughout the board Custom made by MATE so all components can get power

Circuit Boards! MATE Circuit Board BACK OF BOARD This year, MATE has a two-sided printed circuit board. Introduces power to the whole circuit board

Soldering Our Circuit Board Practice Circuit Board Let s practice with these boards before you start on the real circuit board! Wires used to attach to the motor LEDs Switch Resistors Battery connector Circuit board

Soldering Our Circuit Board Practice Circuit Board Your soldered components should resemble smooth, shiny Hershey s kisses. Heat up your component first, then add the solder. Solder will flow towards heat. Clip the remaining wire once you have soldered the joint. Make sure to cover all the holes. Inevitably, you will probably touch the fiberglass a little with your iron small amounts are okay! WEAR SAFETY GOGGLES!

Soldering Our Circuit Board Practice Circuit Board: Resistors and LEDs Let s start with the resistors and LEDs! Insert the resistors POLARITY DOES NOT MATTER! Resistors can be bent and placed either way on this circuit board.

Soldering Our Circuit Board Practice Circuit Board: Resistors and LEDs Solder the resistors on the back side of the practice circuit, then cut off the leads. It helps to bend the leads a little to keep them in place, but don t bend too much because it makes it more difficult to solder.

Soldering Our Circuit Board Practice Circuit Board: Resistors and LEDs Line up the flat side of the LED light to the flat side of the marking on the circuit board. (Flat side also corresponds to the shorter lead or the negative lead) - POLARITY DOES MATTER!

Soldering Our Circuit Board Practice Circuit Board: Resistors and LEDs Insert and solder the LEDs, then cut the leads. Remember, LED POLARITY DOES MATTER!

Soldering Our Circuit Board Practice Circuit Board: Switch Now let s add the switch! POLARITY DOES NOT MATTER! Use tape to keep your switch straight and in place!

Soldering Our Circuit Board Practice Circuit Board: Switch Make sure to cover the holes completely with the solder. WEAR SAFETY GOGGLES!

Soldering Our Circuit Board Practice Circuit Board: Power Wires Does not matter if the cords go into the front or into the back, in this case. Black wire is the GROUND. Red wire is the +9V.

Soldering Our Circuit Board Completed Practice Circuit Board Toggle the switch to see the colors change!

Assembling the Control Box Meter Cords MATE Circuit Board Extra Switches Powerpoles Capacitors Camera Filter Components LEDs Resistors Switch Connector Pins Terminal Blocks Make sure to put the fuse into the fuse container. It should snap in place.

1. Attaching Strain Reliefs Be sure to attach the strain reliefs! Outside of box Inside of box This is important so that when the tether and power cords are pulled, the circuit does not come apart!

2. Assembling the Power Cord Power Cord Fuse Heat Shrink DON T FORGET to place heat shrink on cord BEFORE soldering!

2. Assembling the Power Cord First make sure that the fuse is intact! If it is, insert it all the way into the fuse box. Good fuse Blown fuse This is good! The metal teeth of the fuse should fit snugly into the metal slits in the fuse box. The fuse is not in far enough!

2. Assembling the Power Cord Strip the wire, slip the heat shrink on, twist the wires, solder, hot glue (optional), and heat with heat gun. 1 2 It is optional to waterproof the connection, but it is recommended. 3 4

3. Soldering Resistors, LEDs, and Capacitors Be sure to pay attention to which side of the circuit board to solder on the components! All the terminal blocks are soldered on the back of the board. FRONT BACK WEAR GOGGLES!

3. Soldering Resistors, LEDs, and Capacitors There are four (4) small resistors and three (3) larger resistors. Make sure they are in the correct places! Let s start with the small ones! POLARITY DOES NOT MATTER!

3. Soldering Resistors, LEDs, and Capacitors You can see that the small resistors fit into their printed shape on the circuit board.

3. Soldering Resistors, LEDs, and Capacitors Position the large resistors at the corresponding markings on the circuit board, solder, and trim! POLARITY DOES NOT MATTER! WEAR GOGGLES!

3. Soldering Resistors, LEDs, and Capacitors Place LEDs in their corresponding markings, solder, and trim. REMEMBER, POLARITY DOES MATTER!

3. Soldering Resistors, LEDs, and Capacitors Position the capacitors at the corresponding markings (marked C1, C2, C3) on the circuit board, solder, and trim! POLARITY DOES NOT MATTER! WEAR GOGGLES!

4. Soldering Camera Filter Solder and trim the camera filter components onto the board. The camera filter includes: a capacitor, an inductor, and a diode. Positive Lead Negative Lead REMEMBER, POLARITY DOES MATTER for this capacitor!

4. Soldering Camera Filter Solder and trim the camera filter components onto the board. The camera filter includes: a capacitor, an inductor, and a diode. REMEMBER, POLARITY DOES MATTER! The silver bar on the diode should line up with the PCB The printed side of the inductor should be facing outward (toward the diode)

4. Soldering Camera Filter - Electrical noise from the ROV motors can cause voltage spikes that will damage or destroy delicate camera electronic components - Voltage spikes will also cause video signal disruption every time a motor is running - A simple camera filter will remove any issues and provide clean power to your camera

5. Soldering Power and Meter Terminal Blocks Solder the ammeter, voltmeter and power terminal blocks onto the board. Power In terminal block Meter terminal blocks POLARITY DOES NOT MATTER, BUT ORIENTATION DOES! Front Back You can use electrical tape to secure the blocks while soldering. This side should be facing out from the circuit board

6. Adding the Switches Now let s talk about adding switches! IMPORTANT! Test all your switches (including the spares) first before you start soldering! The black represents the negative terminals and the red represents the positive terminals of each switch. Gnd +12 V

6. Adding the Switches These rocker switches control the motors. They are double pole double throw (DPDT) switches. Black wire Brown wire Think about your motors: What happens when you connect brown to positive and black to negative? What about when you connect black to positive and brown to negative?

6. Adding the Switches The propeller will rotate FORWARD.

6. Adding the Switches The propeller will rotate IN REVERSE.

6. Adding the Switches Using the spare switches in your kit, mount all the connector pins neatly onto each switch. Make sure they are all in the same orientation. The prongs on the pins will line up with the holes in the circuit board. Secure the pins, but DO NOT push the pins ALL THE WAY down on the switch.

6. Adding the Switches Insert the switches into the circuit board so the prongs matches the orientation on the printed board, and solder the pins into place. Make sure the connector pins are pushed all the way through the holes of the circuit board. Remember the Hershey Kiss shapes?

6. Adding the Switches Solder the rest of the switches (connector pins) onto the circuit board. At this point, the switches should still be securely in place, but they SHOULD NOT be pushed down all the way.

7. Testing the Switches and Power Before continuing, test to make sure the connector pins were soldered well. You can do this using a digital multimeter (on Ohms). To do this, add a jumper to bridge the gap in the ammeter. Cut a 3 cm length of 16 or 18 gauge wire and strip the ends. Insert and secure the wire between the YELLOW and BLACK slots in the terminal block. Secure the wires using a small flathead screwdriver.

7. Testing the Switches and Power Insert the multimeter leads into Power In terminal block (red lead into +12V, black lead into GND). You can secure the leads by tightening the screws at the top of the terminal block. Turn the meter to Ohms. The meter should read greater than 1 MΩ (or start low and slowly climb to greater than 1 MΩ. Push one of your switches UP and hold. The meter should drop to 0.00 Ω and then move back to greater than 1 MΩ. Repeat the process for DOWN on that switch. Repeat the process for the other two switches. If your controller passes all six tests (all three switches, both directions), continue. If it fails, inspect the solder joints on both sides of the board. If your solder looks good and only one switch failed, try installing a different switch into the pins.

7. Testing the Switches and Power After passing the test using the multimeter, you can test the board using power. Replace the multimeter leads with a length of red/black power wire to connect the Power In terminal block to a 6V or 9V battery. WEAR GOGGLES! LED4 is the power indicator. It will shine GREEN if the board is receiving power. If it is not lighting up, check the battery connections, solder joints and whether the diode was installed correctly (polarity).

7. Testing the Switches and Power Now test each switch by pushing down on the up and down buttons, one at a time. LED1, LED2 and LED3 are the indicators for each switch. When the switches are pressed UP, the lights should turn GREEN. When the switches are pressed DOWN, the lights should turn RED. After testing, remove the jumper from the ammeter terminal box. Remember, when the power is ON, the only light that should be lit is the green LED next to the capacitor (LED4). The rest should only shine when the switches are pushed. Remove all three switches from the pins carefully. If you pushed them down all the way, you may need to use a screwdriver to remove them.

8. Soldering Remaining Terminal Blocks Solder the remaining terminal blocks for the motors and AUX wires. Make sure the terminal blocks are secure before soldering! POLARITY DOES NOT MATTER, BUT ORIENTATION DOES! Front Back This side should be facing out from the circuit board

9. Attaching the Meter Wires Now the meter wires need to be attached to the screen and the terminal blocks. Notice the notches on the plastic inserts and how they are placed in the circuit. These should click in place. At this time, the switches in the control box lid have not been inserted into the connector pins (on the circuit board) yet.

9. Attaching the Meter Wires Secure the wires in the corresponding color slots for each terminal block. The thinner wires will go into the voltmeter terminal block and the thicker wires will go into the ammeter terminal block. TIP: The distance between the two bars on the side of the terminal block indicate how much wire should be exposed. The thinner wires will go into the RED/BLK block. The voltmeter wires need to be stripped (about 1.5 cm), folded in half and twisted so it fits all the way inside the terminal block.

9. Attaching the Meter Wires Secure the wires in the corresponding color slots for each terminal block. The thicker wires will go into the corresponding colors (yellow wire in YEL, red wire in RED, black wire in BLK) of the ammeter block.

9. Attaching the Meter Wires The wires should be secured tightly so they do not come loose. Give each wire a gentle pull to make sure all five wires are secure. Notice that NO EXPOSED WIRE (uninsulated) is showing. If any wire can be seen from any angle or any strands are loose, your control box will not pass the safety check.

10. Affixing Board to Control Box Lid Now it is time to connect the switches with the connector pins. Once ALL the pins are aligned, push the whole circuit board hard until all the pins click into place. Connector pins need to be pushed ALL THE WAY onto the switches. Pins pushed all the way down.

11. Testing the Board (with Power) Use the completed power cord from Step 2 before and test the control box. Make sure the fuse is installed. On the opposite end of the Anderson Powerpoles, strip the wires just enough so the exposed wire fits inside the terminal block. This wire is too exposed, so it needs to be trimmed before it is secured again.

11. Testing the Board (with Power) Once the power wires are secured and the Powerpole connections are in the battery, turn the control box over and test each switch.

12. Connecting the Tether Now that your switches work and there is power, SWITCH OFF the power source and remove the power wires from the terminal block. It s time to connect the tether. Strip the wires and place them in the motor terminal blocks. Remember the Tether PPT from before? Pull the loose end of the tether (opposite of the motors) through the top strain relief.

12. Connecting the Tether When you re ready to attach motor wires, think about which switch corresponds to which motor. It doesn t matter which colors you use for each motor, just REMEMBER THE PAIRINGS! It is important to make sure the control box wiring matches the motor wiring. Have your students keep track here is an example chart. Motor/ Switch MTR1 Left Switch MTR3 Center Switch MTR2 Right Switch Wire/Pad Pairing Green (+) = Pad A White (-) = Pad B Brown (+) = Pad A Black (-) = Pad B Red (+) = Pad A Blue (-) = Pad B For this, the brown wire on the motor is positive and the black wire is negative.

13. Connecting the Power and AUX Make sure that the POWER and AUX (video) cords are pulled THROUGH the strain relief! This is the AUX/video cable that you made from before (in the Camera PPT).

13. Connecting the Power and AUX Reconnect the Power cord to the Power In terminal block. Once all AUX cords are pulled through the strain relief, connect the red wires together and the black wires together. You can solder these together if you wish. RED AUX wires in +12V BLACK AUX wires in GND Twist the AUX pairs of wires together, bend them in half and twist them together again. This is so they will stay secure in the terminal block.

Assembling the Control Box MATE Circuit Board Summary of Steps: 1. Attaching the strain reliefs to the control box 2. Assembling the power cord 3. Soldering the resistors, LEDs and capacitors to the circuit board 4. Soldering the camera filter components 5. Soldering the power and meter terminal blocks to the board 6. Adding the switches to the board (after testing) 7. Testing the switches and power 8. Soldering the motor and AUX terminal blocks to the board 9. Attaching the meter wires 10. Affixing the circuit board to the control box lid 11. Testing the circuit board (with power) 12. Connecting the tether (motor) to the circuit board 13. Connecting the power and camera/aux to the circuit board

Assembling the Control Box Once everything is tightly secured, screw the top of the circuit board securely in place and tighten the strain reliefs. After assembly, test to make sure everything still works! Make sure the wires do not come loose or get pulled out of the terminal blocks and you do not see any exposed copper wire! BAD GOOD

COMPLETED Control Box! Congratulations! You have now finished your ROV control box!

Powering your ROV! To power your ROV, use the Powerpole adapter and plug everything into the car jump-start battery, and then we fly! Good luck, everyone!