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Classes/2010/VIS147A/Labs

2,023 bytes added, 04:55, 20 January 2010
→‎Lab 2 - Voltage, Current, Resistance
* Electricity flow.
* Voltage, Current, Resistance.
* Ohm's law. '''V = I * R'''
* SI units. (Volts, Amperes, Ohms)
 
== Supplies ==
* 4 6V bulbs [http://www.jameco.com/Jameco/Products/ProdDS/210008.pdf datasheet] "MSCP" stands for "Mean Spherical Candlepower" [http://www.electrical-online.com/lightingterminology.htm] p. 507 Scherz.
== Activities ==
=== Part 1: Set up your 5V power supply===* set Set up the voltage regulator on your breadboard. This chip, the LM7805 is a "5 volt regulator", meaning it takes an INPUT voltage ("+12V" from your adapter), and turns it into an OUTPUT voltage , +5V. It also needs to be connected to GROUND. This is a diagram of the regulator:  [[Image:7805_schematic.png | 350px | thumb | left 300px ]] Notice the regulator has three legs. Each of these legs has to be connected to the right thing. From page 2 of the datasheet for the regulator [http://www.fairchildsemi.com/ds/LM/LM7805.pdf] , under "Pin Assignment" we see what each of the legs are. Looking at the front, they are numbered 1, 2, and 3, from left to right, and are labeled "Input", "GND", and "Output": [[Image:7805_pinout.png | 200px | thumb | left]] TIP: use your pliers to insert the 7805 into the breadboard. Its legs are thicker than your typical wire/resistor/LED, and sometimes are hard to get into the board. On the breadboard the circuit will look like this: [[Image:7805_on_breadboard.jpg | 300px | thumb | left]]* Set up a light bulb as indicator (always-on to be a power indicator), as shown in the images below: [[Image:7805_schematic_w_bulb.png | thumb | left]][[Image:7805_with_power_light.jpg | 200px | thumb |left300px]]*QUESTIONS:**what is the voltage across the bulb?**what is the voltage across the input to the voltage regulator?**what is the voltage across the output from the voltage regulator? **how much current is flowing through the bulb? according to the [http://www.jameco.com/Jameco/Products/ProdDS/210008.pdf datasheet] how much current should the bulb draw?
=== bulb circuits===* Scherz p 49. 2.11 Electric Circuits[[Image:7805_with_power_light.jpg | 300px]]
[[Image:Four_series_of_bulbsConnect your power supply.png | 200px]] If your board has power, the bulb should turn on.
'''Be careful with the regulator when the power is on, it may get hot!!!'''
QUESTIONS. With your multimeter, answer the following:*what is the voltage across the bulb?*what is the voltage across the input to the voltage regulator?*what is the voltage across the output from the voltage regulator? *how much current is flowing through the bulb? According to the datasheet for the bulb [[Imagehttp:Parallel_bulbs//www.png | 200px]jameco.com/Jameco/Products/ProdDS/210008.pdf], how much current should the bulb draw? REMEMBER: measuring current with a multimeter is different than measuring voltage. You need to "break the circuit" and re-connect it through the multimeter.
=== Part 2: Series and Parallel (with bulbs)===
For each of the following diagrams, rate the relative brightness of the bulbs. '''Use a scale of 1 to 5, with 1 being brightest and 5 being most dim.''' You can sketch them by hand and do this on your own paper, or you can print out the images from this pdf [[Imagehttp:Mixed_bulbs//wiki.png | 200px]roberttwomey.com/images/a/a3/Series_parallel.pdf].
=== resistor To get you started, the bulb in diagram 1 will have a brightness of "1"--the brightest a bulb will be in any of the circuits=== * resistors.
[[Image:Resistor_seriesSeries_parallel1.png | 200px400px]]
[[Image:Resistor_parallelSeries_parallel2.png | 200px400px]]
[[Image:Resistor_mixedFor help, see Scherz p 49, "2.11 Electric Circuits".png | 200px]]
* potentiometer=== Part 3: Series and Parallel (with resistors)===
[[Image:PotentiometerWorking in pairs, wire up the circuits and verify the voltages and currents you calculated for circuits 1-5 in last week's homework.png | 200px]] [[Image:Potentiometer_w_bulb Get help from your TA in determining which resistors are which using the resistor color code. The color code is described on the back side of the first page in the Scherz book.png | 200px]]
'''Don't build circuit #6!! I will show it to you in class.'''
* power rating...but here is the rationale if you want to think about it: DONT TRY THIS AT HOME, ONLY IN LAB! *We have a 5 Volt supply and a 10 Ohm Resistor.*The resistor is rated at 1/4 of a Watt = , or 0.25 WattWatts. **P=I*V. P=I*5V. 10 Ohm resistor* this amounts to a brief (and cautionary) demo of what a '''power rating''' is, and why it is important.
= Lab 3 - Switching, Circuits, Control =
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