Some common electrical components

  1. breadboard jumper wire
  2. resistor: colour code gives resistance in Ohms
  3. inductor: value or colour code as for resistor gives inductance in microHenrys, uH
  4. non-polarized capacitor, value in picoFarads,
    i.e. 223 == 22*10^3 pF
  5. power diode, black with silver ring
  6. polarized (electrolytic) capacitor, note "+" and "-" leads, value is in microFarads, uF
  7. LED, longer lead is +ve (anode)
  8. bipolar transistor
  9. integrated circuits, 8 and 14 pins
Here are some standard circuit schematic symbols.

The breadboarding workstation

You will be using a breadboarding workstation to assemble and test your hands-on circuits. The solderless breadboard provides a convenient way to assemble easy-to-modify circuits and to connect to power sources and test equipment with trouble-free connections.

To the left are three BNC jacks for connecting coaxial cables to the waveform generator and oscilloscope. The two three-way SPDT switches can be used to control your circuit behaviour.

Your workstation has two solderless breadboards, arraged side-by-side. They are not electrically connected. Further information on the solderless breadboard and breadboarding techniques can be found here.

A breadboard consists of a matrix of holes, electrically connected in groups. The central region of the board is split into groups of five connected pins.

Along the long edges are rows of connected pins, labelled (+) and (-), typically used to distribute power to the board. On some breadboards, these rows are split into two halves that are electrically disconnected at the centre.

Flip your breadboard upside down to view these internal connections. Conductive strips of metal electrically connect groups of holes so that two or more components become connected when inserted into holes belonging to the same group.

Note: connecting different voltages to the same group of holes will result in a short circuit and possibly damage the power supply or other circuit components.

The Component Tester

The component tester can automatically determine the type of electrical component under test and measure it's electrical characteristics.

The tester can measure resistance, capacitance, inductance.

The tester can determine type and pinout of semiconductors such as a diode, Zener diodes, bipolar and field-effect transistors.

The zero-insertion-force socket accomodates components with two or three leads. Each lead is inserted into a hole with a different number. Note the pattern 1-2-3-1-1-1-1.

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The multimeter

The multimeter (MM) displays a result with a measurement error of less than 0.004% and a precision of 6 digits.

For example, when measuring a 5.0 Vdc signal with the MM, the error is ~0.004%, or ~0.2mV. Then, the displayed reading would fall between 4.9998 V and 5.0002 V, or Vdc = (5.0000 ± 0.0002) V.

Measuring a 1 kΩ resistor (brown,black,red,gold) with the nominal component tolerance of 5%, i.e. R = (1000 ± 50) Ω,
with CT, R = (984.7 ± ?) Ω, with MM, R = (982.95 ± 0.04) Ω

The picture shows the MM measuring the resistance of the probes. Note that holding a resistor during a measurement will change it's temperature and hence the result.

1

The Instek GDS-1102 oscilloscope

Press Autoset to have the scope detect the input signal(s) and try to automatically set optimal gain, timebase and trigger values. Otherwise, follow these steps to optimize the scope display:
  1. select/enable a channel with the CH1 and CH2 keys;
  2. verify that Invert=off, Voltage=1x, Coupling is DC;
  3. adjust the voltage gain with the VOLTS/DIV knob;
  4. adjust the vertical 0V position with the up/down knob;
  5. adjust the timebase with the TIME/DIV knob;
  6. adjust the time=0s position with the left/right knob;
  7. in the trigger menu, select the source channel and slope;
  8. set the trigger voltage level within the signal vertical range to stabilize the waveform on the screen.

The oscilloscope is connected to the breadboard using BNC (Bayonet Neill-Concelman) coaxial cables. The two black cables are connected to the scope input channels CH1 and CH2. The yellow cable is here connected to an off-screen waveform generator that provides a signal to the breadboard circuitry.

Press RUN/STOP to continuously trigger or pause the display; press SINGLE to wait for and capture a transient signal.

To minimize the relative error when making measurements with the scope cursors, always adjust the scope settings to get a steady waveform and expand the region to be measured to occupy a maximal region of the scope screen.

The accompanying picture, as rendered by the GDS-1102A applet available on all the Linux workstations, shows typical scope waveforms (CH1=yellow, CH2=blue). Markers 1> and 2> on the left identify the channel V=0 levels, here set to be the same.

The < marker on the right shows the trigger level for the selected channel, here CH1, while the trigger time offset, from t=0 at centre of grid, is displayed on top. Their intersection, shown by the cross symbol, defines the trigger point on the waveform.

The bottom of the screen displays the individual channel gains and common timebase per grid division. The frequency of a periodic signal may also be shown.

The two vertical framing cursors are here set to measure the time difference between two waveforms aligned to the same voltage level, V1=V2=0.

THe window at the bottom right corner allows the user to enter relevant circuit parameters that will be stored, along with the scope settings, as part of a saved data file.