Short STEAM course Electronics support notes

 

 

1.    Series circuits. In a series circuit current is the same everywhere. An ammeter can measure the current in Amps.

 

 

 

 

 

 

 

 

 

 

2.    Circuit symbols:

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3.    Resistors are used to control the current in a circuit. The higher the resistance the lower the current.

 

Variable resistors can vary the current in a circuit eg. to dim a lamp or vary the speed of a motor.

 

Units of resistance are Ohms ( Ω). 

 

 

4.    Multimeters are used to measure Voltage (Volts), Current (Amps), and Resistance (Ω).

 

For small quantities milli (m) may be used eg.  mA

 

For large quantities kilo (k) may be used eg. kΩ

 

 

5.    LEDs are used in displays or as indicator lamps.

 

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              You should know the circuit symbol for an LED.

 

              High currents will cause LEDs to overheat, so they must be protected by using a current

 

              limiting resistor as shown above.

 

              LEDs only work one way ie. current flowing from A to B (in direction of arrow). If current

 

              flows in the reverse direction, B to A, LED does not light up (we consider the reverse

 

              resistance of an LED to be very high).

 

 

6.    Pulse Producer IC (or integrated circuit). This is a digital oscillator device whose output is a train of 1s and 0s:

 

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              The ON time (1) can be equal to the OFF time (0), as above. Eg. this would cause an

 

              LED to flash in a regular way.

 

 

 

 

             

 

Or the ON time can be short compared to the OFF time (A), Or the OFF time can be short

             compared to the ON time (B).

             Either A or B would cause an LED to flash in an irregular way.

 

7.    Counting pulses with a binary counter IC using LEDs.

 

 

 

 

 

 

 

         

 A complete table of outputs for the binary counter:

                    

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8.    7_seg_pin_config-300x266Making decimal numbers on a 7 segment display:    

 

 

 

 

 

 

 

 

 

          

            Eg. a number one is made if segments b and c are ON whilst all other segments are OFF.

 

                  a number zero is made if segments a, b, c, d, e, f are ON whilst segment g is OFF.

 

                  Etc.

 

Screen%20Shot%202017-05-08%20at%2012.57.40.png             An electronic decoder IC is used to create decimal