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Learn the essentials of analog electronics including resistance, current, voltage, and Ohm's Law. Master the use of meters and scopes, and practice solving Ohm's Law exercises. Build a solid foundation in electronics principles!
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Electronics and Robotics Merit Badges Class 2 – Analog electronics Electronics and Robotics Merit Badges - Class 2
Remember this “Equipment Used” Volt/Ohm/Amp Meter or Multimeter Usually referred to as meter. With this we can measure current, voltage and resistance. Oscilloscope Usually referred to as scope. With this we can ‘see’ voltages. This is very useful when voltage is changing, as a meter is no good to us when this is happening. 10/29/2019 Electronics and Robotics Merit Badges - Class 2 2
Resistance • Resistance is an electrical property of a material that “resists” the flow of electrons. • The schematic symbol for a resistor is: • Common units for resistance are: • Unit of resistance is OHMS • Kilohm: 1K= 1000 ohms, 10K = 10,000 ohms • Megohm: 1M = 1,000,000 ohms • The units symbol for ohms is: Ω (ohms) Electronics Merit Badge Class 2
Current • Current: Defined as “flow of electrons”. • Current: Units of current is AMPS. • Current: Electrical symbol for current is I. • Common units for current are: • Amps • Milliamps (ma): 1 ma = .001 amp • Microamps (ua) : 1 ua = .000001 amp, or .001 ma • Nanoamps (na) : 1 na = .000000001 amp or .000001 ma, or .001 ua. Electronics Merit Badge Class 2
Voltage • Volts is the electrical force that causes electrons (current) to flow. • Units of volts is VOLTS. • The symbol of volts is E or V. We will use V. • Common units for voltage are: • Volts • Millivolt (mv) : .001 volt. • Microvolt (uv) : .000001 volt, or .001 mv • Nanovolt (nv) : .000000001 volt, or .000001 mv, or .001 uv. Electronics Merit Badge Class 2
Ohms Law One of the most important laws in electronics/electricity. V = I x R : Voltage = Current x Resistance Volts is measure in VOLTS, current is measured in AMPS, and resistance is measured in OHMS. 1 AMP, going through 1 OHM of resistance, generates a voltage drop of 1 VOLT. 1 V = 1 A x 1 Ω. Electronics Merit Badge Class 2
More Ohm’s Law Different forms of Ohm’s Law: V = I x R : Voltage = Current X Resistance I = V / R : Current = Voltage / Resistance R = V / I : Resistance = Voltage / Current Volts = 10. Resistance = 1000Ω Compute current. I = V / R I = 10 / 1000 = .01A .01A = 10ma Question: What would the current be if the voltage was 1 V? How about 1000 V? + 10V 1000 Ω Electronics Merit Badge Class 2
Ohm’s Law Exercise Let’s use Ohm’s Law some. Do this in your Robotics Engineer’s Notebook. You will need to do this again when we start to build robots. Remember that Ohm’s Law is: VOLTAGE = CURRENT X RESISTANCE V = I * R OR R = V / I AND THAT I = V / R (maybe you should write these in your engineers notebook?!) Electronics Merit Badge Class 2
Ohm’s Law Exercises GIVEN: FIND: 1) I = 2 AMPS V = ______ R = 10 OHMS 2) V = 12 VOLTS R = ______ I = 3 AMPS
Ohm’s Law Exercises GIVEN: FIND: 3) V = 15 VOLTS I = ______ R = 3 OHMS EXTRA CREDIT: POWER = VOLTS X CURRENT P = V * I
Ohm’s Law Exercises GIVEN: FIND: 4) V = 120 VOLTS P = _____ WATTS I = 5 AMPS So now that we know about volts, ohms and current lets get back to our Electronics Kit!
Microprocessor Controlled Counter Electronics Merit Badge Class 1 The kit contains a microprocessor that will drive 12 LEDs in a diminishing pattern. The LEDs can be displayed in many different modes, though each mode starts as a fast pattern, and eventually slows to a stop. 10/29/2019 Electronics and Robotics Merit Badges - Class 2 12
Microprocessor Controlled Counter 10/29/2019 Electronics and Robotics Merit Badge - Class 2 13
Let’s use the meter to measure one of the LED resistors Meter 000 SET METER TO RIGHT Ω RANGE Using the meter, measure Resistance on one of the LED resistors R = _________ ohms
Then lets measure Kit Battery Power Supply Voltage Red + Black 4.5 VOLTS First check the battery power supply. It should be about 3-4 VOLTS (3 X1.2-1.5 VOLT batteries). If unit does not work, have an instructor check it for problems. 10/29/2019 Electronics and Robotics Merit Badges - Class 2 15