What is the voltage V 1 and the current i 3 ? 300 400 v 1 10V 4V - - PowerPoint PPT Presentation

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Jul 05, 2023 123 likes •318 views

What is the voltage V 1 and the current i 3 ? 300 400 v 1 10V 4V i 3 Submit your answer on menti.com with code 85 57 1 ENGR 40M, Lecture 4: Diodes and solar cells Steven Bell 3 July 2016 By the end of today, you should be able to: Find

SLIDE 1

What is the voltage V1 and the current i3?

Submit your answer on menti.com with code 85 57 1

10V 4V i3 300Ω 400Ω v1

SLIDE 2

ENGR 40M, Lecture 4:

Diodes and solar cells

Steven Bell

3 July 2016

SLIDE 3

By the end of today, you should be able to: Find currents and voltages in a circuit containing current sources and diodes Model a solar cell using a current source in parallel with a diode Explain how multiple solar cells are used to build a solar panel

SLIDE 4

What do you need to know to design and build a solar-powered phone charger?

SLIDE 5

anode cathode

If it helps you remember: "cathode current departs"

Diodes are like one-way valves for current.

SLIDE 6

If the voltage is negative, no current flows (open circuit) If the current is positive, no voltage drop (short circuit)

For an ideal diode:

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Which diodes turn on? (i.e., which have current > 0?) A B C

1V

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But real diodes aren't ideal

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The "idealized" model is a compromise

Vf

The diode turns on at Vf, the "forward voltage"

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Which diodes turn on?

Assume that Vf = 0.6V

A B C D E

1V 10mA

SLIDE 11

What is the current through the diode? Vf = 3V

5V

R = 100Ω

i

SLIDE 12

Breaking break:

smashing apart a diode

SLIDE 13

https://youtu.be/IcrBqCFLHIY https://youtu.be/b3xys6rYM_Q

To learn more:

There are entire classes on these topics, like EE116 Veritasium: How does a transistor work? Doc Physics: How does a diode work? https://youtu.be/JxOTulMExWU Doc Physics: How solar panels work

SLIDE 14

Our model for a solar cell

They're a current source, but they're also still diodes

If the current has nowhere to go, it just goes back through the diode

SLIDE 15

A single solar cell gives us about 0.6V Our solar panels provide ~8V - how?

SLIDE 16

SLIDE 17

iout Suppose one cell out of six gets blocked (i.e., no light). What happens to the output current? A) 5/6 current (83%) B) 1/2 current (50%) C) No current (0%) D) Something breaks or burns

SLIDE 18

What happens if you connect your panel to a battery, and leave it in the dark?

A) Nothing B) The solar panel charges the battery a tiny but measureable amount C) Current flows through the solar panel, discharging the battery D) C, and this breaks the solar panel