op-amp oscillator. reading schematics: battery what’s this?
TRANSCRIPT
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Op-Amp Oscillator
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Reading Schematics:
• Battery
What’s this?
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Reading schematics
• Store electrical energy in an electric field (static electricity).
• Uses include:– Timing circuits– Coupling circuits– Energy storage– Bypass circuits– Filter circuits
Eric SchraderCC BY-SA 2.0
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Capacitors
Eric SchraderCC BY-SA 2.0
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How about this?
• Resistor
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Operational Amplifier
• Very popular integrated circuit
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What’s it for?
• Just about everything! • Depends on how you hook it up
– Convert current to voltage– Convert voltage to current– Amplify voltage– Amplify current– Compare voltages
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This one does NOT have feedback
• No connection from output back to input
• This will amplify any difference in voltage between the inputs
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Gain is about a zillion• Suppose Vin is greater than Vref
(this would be when the room is dark)
• Comparator multiplies difference by a zillion, wants to go to a zillion volts
• But, battery is only 9 V, so that’s as high as it can go
• Similarly, can’t go lower than 0V
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Operation:
• If input higher than ref, output goes to 9V
• If input lower than ref, output goes to 0 V
• Nothing in between
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Comparator
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Positive Feedback
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Voltage Divider
• Also called voltage divider• Ohm’s Law: V=IR• Same current flows through both resistors
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Voltage Divider
If R1=R2, then Vout will be half of Vin.
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Voltage Divider
If R1=R2, then Vout will be half of Vin.
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Timing Circuit
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RC Circuit
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The breadboard
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The buses
Every hole along this green line is electrically connected
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There are four buses you can use
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All rows connected too
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To connect to your devices
• Recommend putting displays across center channel
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To make connections
• One end of wire is connected to the bus– And anything else
connected there
• Other end is connected to one pin
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Connect common anode to positive bus
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• R2 = R3 = R4• Time: R1, C1
4
8
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