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The Analog Feedback Machine Full Schematic. Parts List. Water Analogy - How Electricity Moves. Voltage = Water Pressure - Stored Potential Energy Current = The Amount of water flowing through an area at a given time. Positive current convention tracks flow from positive voltage to negative
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Water Analogy - How Electricity Moves Voltage = Water Pressure - Stored Potential Energy Current = The Amount of water flowing through an area at a given time. Positive current convention tracks flow from positive voltage to negative Electrons flow from negative to positive.
Electricity Basics - The DC Circuit Battery Lamp Switch
Electricity Basics - The DC Circuit Current flows when the switch is closed.
Basic Theory + Parts • Imagine a circuit like a system of pipes and valves • Battery = water pump • Conductors/Wires = main pipes • Resistors = smaller pipes of varying sizes • Capacitors = water balloons • Transistors = valves controlled by water flow • Integrated Circuits = pre-built, super miniature circuits
Transistors Transistors come in many flavors these days. Bipolar Transistors are semiconductor components with the three connections: Base, Emitter, and Collector A small current flow applied to the Base of the transistor permits a larger (and proportional) current flow between the Collector and Emitter NPN - is active when a positive current relative to the emitter is applied to its base PNP - is active when a negative current relative to its emitter is applied to its base NPN PNP
Transistors can be used as an electrically controlled switch! Applying a positive current to the base of T1 at 5 volts through the 47k ohm resistor causes it to go into saturation.
Transistors can be used to drive LEDS as shown: Applying a positive current to the base of T1 at 5 volts through the 47k ohm resistor causes it to go into saturation. Current then flows through R1 and the LED causing it to light.
IMPORTANT NOTE! • Our Transistors have a non-standard pin-out • From Left to Right (with flat side facing you and legs pointed down) Pin 1 = EMITTER Pin 2 = COLLECTOR Pin 3 = BASE
Operational Amplifiers • Two inputs • Non-Inverting (+) • Inverting (-) • Fixed gain factor • Open loop gain • Feedback used to control gain and to produce other useful circuits.
Virtual Ground • Analog audio signals swing both positive and negative relative to a fixed voltage. • When powering audio electronics from a battery supply, a virtual ground reference must be generated. • This can be done using a voltage divider and a voltage follower.
Circuit Breakdown • Inputs • Touch Pads (thumb tacks optional) • Circuits • Voltage Divider • Voltage Follower • Inverting Amplifier • Summing Amplifier
