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Published byJewel Barker Modified over 9 years ago
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Essmart Hackathon Peter Burkimsher and Sreechand Tavva
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What to expect A basic introduction to electricity How to read a circuit diagram Common electrical components Series and parallel circuits What not to do Advice for best practice Build your own multi-brightness LED!
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Electricity - 1 V+ GND
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Electricity - 2 V+ GND
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Electricity - 3 V+ GND
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Voltage - 1 5 V V+ GND
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Voltage - 2 2.5 V V+ GND
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Voltage - 3 0 V V+ GND
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Current - 1 0.001 A V+ GND
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Current - 2 1 mA V+ GND
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Current - 3 500 mA V+ GND
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Shorting out 500 mA 5 V V+ GND
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Circuits 500 mA 5 V V+ GND
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Resistor 20 mA 5 V V+ GND 4.7 kΩ100 Ω
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Diode 5 V V+ GND V+ GND
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Diode warning 500 mA 5 V V+ GND
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LED 5 V V+ GND V+ GND
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Practical 1 – Series LED
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Practical 2 - Switch
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Switches 0 mA 5 V V+ GND
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Practical 3 – Series Resistors
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Practical 4 – Parallel Resistors
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Variable Resistor 5 V V+ GND
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Practical 5 – Variable Resistor
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Practical 6 – Parallel switch
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Thank you for your participation!
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Circuit Diagrams - LED Here is a simple circuit diagram. It shows an LED connected with a resistor in series. We will build this soon! Colours are optional, I added them for clarity.
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Circuit Diagrams - Switch Now let’s add a switch in series. What happens when you turn the switch on – The LED lights up The black dot joins two or more wires
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Series – 1 So far, all the components we connect are in series, one after another. In a series circuit, there is only one path for current to flow. Let’s add 2 more resistors in series.
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Series – 2 The total resistance is the sum of each component’s individual resistance. R total = R1 + R2 + R3 R total = 4.7kΩ + 4.7kΩ + 0.1kΩ R total = 9.4kΩ + 0.1 kΩ
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Series - 3 When the resistance increases, the current through the LED is smaller. What happens to the brightness of the LED when there are 3 resistors in series, compared to only 1 resistor? – The LED becomes dimmer.
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Easy Maths Voltage V is the current I multiplied by the resistance R. V = I × R Therefore R = V ÷ I, and I = V ÷ R V I R
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Parallel - 1 What if you connect the 2 resistors next to each other? There are 2 paths for the current to flow. How much flows through each?
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Parallel - 2 The ratio of current flow depends on the resistor values. If the resistors are the same – The total resistance is half. – For us, that means 4.7 ÷ 2 = 2.35 kΩ
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Parallel - 3 The resistance is smaller than it was when a 4.7kΩ resistor was attached in series. What happens to the brightness of the LED? – The LED becomes brighter
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Voltage Divider - 1 If you connect two resistors in series from V+ to GND, you can build a voltage divider. The point between the resistors sees half the voltage (V+/2) relative to GND.
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Voltage divider - 2 If you connect an LED in parallel with the second resistor, the voltage across that part of the circuit is V+/2. For our 5V supply, this means only 2.5V.
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Voltage Divider - 3 Voltage dividers can be tuned to achieve any voltage less than or equal to the V+ voltage. The voltage across the LED depends on the ratio of the resistances. A variable resistor lets us change this quickly.
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What not to do – 1 Please don’t short out your power supply! All of these circuits are shorted out. Always connect a resistor in series to the LED!
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What not to do – 2 Don’t plug components in randomly. You should understand the circuit, and know how to get it right first time. All of these circuits are the same:
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Best practice Check that your connections are strong. Screw a wire in tight, so you can’t pull it out. Wires shouldn’t touch outside the block. If a wire becomes frayed, twist it together and “tin” it (cover it with solder). Label your components with red and black pens if direction matters.
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We’re ready to build! Finally, we’ve been through enough theory. Let’s build some circuits! This should be quite quick, now you know what you’re doing. I’m going to show a circuit diagram, and you have to build it. When it’s ready, you can test it by plugging it into your power supply!
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Practical 8 – Everything Let’s use everything we learned to build a full circuit with all the features we want! The switch activates maximum brightness The variable resistor controls brightness
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Practical 5 – Voltage Divider A voltage divider places the LED in parallel with the second resistor. This should be half as bright as when the LED was in series with only the 100Ω resistor.
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Changeover Switch Changeover switches let you choose 2 inputs. If one pipe is empty, a changeover switch is the same as a normal on/off switch. Our switches have 3 connectors for this. – We will leave one disconnected. Electronic symbol: 0 mA 5 V V+ GND
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What not to expect Lots of maths – I did the calculations first. A finished product – You have to build it! Everything you need to know to build a robot/radio/phone charger/solar-powered lantern. – This is to get you started. You can look up instructions for new projects on the web!
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