Experiment 1 Breadboard Basics Week 1 Experiment 1 Breadboard Basics

Breadboard Basics The goal of Experiment 1 is for you to identify on the breadboard of the ANDY board: which of the rows of pins are connected (shorted) together and which of the set of pins in columns are connected together so that you will be able to construct the circuits properly in the experiments that follow.

ANDY board The breadboard on the ANDY board is the white section with the rows of pins. It is used to hold components and to allow easily wiring between the power supplies on the ANDY board to the components and from the component to component to form a circuit. The squarish holes are where wires or the legs of your components are inserted. Inside each hole is a set of leaf springs that clamp on to the wire or end of the component inserted into the hole.

This is the back surface of the breadboard, which one of the ECE lab staff removed from the board similar to the ANDY board. Some metal strips run horizontally and some run vertically. These strips create a low resistance connection between the sets of square holes along the metal strip to allow you to easily connect ends of components together without running wires between them. Wires are used to make jumpers between metal strips. Maximum frequency of operation is 4 MHz, due to parasitic capacitance

Typical Pattern of Connections Your job in Experiment 1 is to determine which set of holes in specific columns and rows are connected by these metal strips on the ANDY board. .

MY-64 Digital Multimeter An instrument that is used to measure: DC voltage and DC current AC voltage and AC current (RMS values) Resistance up to 200 MW Continuity Commonly used to determine polarity of diodes Capacitance at 20 kHz Frequency of a sinusoidal voltage Low frequency hfe (or b) of a transistor Temperature Measured with thermocouple probe.

Before you use the DMM Change the battery in the multimeter. The current 9V battery was inserted when the multimeter was manufactured. The battery has about a 1 year shelf life. Errors in measurements can be greater than 10% when the battery voltage is low. This is greater than the measurement error allowed in the grading program. Failure to replace the battery with a new one may cause you to lose points on your post-validation report. There should be a new battery in your parts kit. Directions are available online at http://filebox.ece.vt.edu/~LiaB/Equipment/DMM/Changing_Battery.pdf

Digital Multimeter Resistance measurements can be made directly using a digital multimeter (DMM). The probes are inserted into the V/W/T plug or jack (red probe) and the COM jack (black). Note that the dial on the meter is positioned at the 20k mark within the W measurement region.

Probes The probes that come with the DMM have tips that are too large to fit into the holes on the ANDY board breadboard. Do not force them into the holes as this will damage the leaf springs within the holes. There are a set of banana jack probes in the probe kit that is offered by Electronix Express that have smaller tips, which you can use instead. Or you can use a small length of wire wrapped around each of the original probe tips that you then insert into the holes. Banana jacks

Resistance Measurements Set the dial to the maximum resistance value. When there is only air between the tips of the red and black probes, the reading on the DMM is in the ‘overflow’ condition as air is an insulator and the resistance of air is greater than 200 MW. A “1” off to the left with no other digits displayed. When there is a very conducting material placed between the two tips, the measurement should be 0.00, indicating that the resistance of the material is much less than 200 MW. You should rotate the dial to a lower resistance range until you either reach the lowest range or an ‘overflow’ condition is indicated. In the first case, you should record the measurement. In the latter case, you should set the range to the next highest setting and then record a measurement.

Potential Issue Follow the pattern described in the laboratory manual to map the position of the metal strips that connect sets of holes (pins) on the ANDY board breadboard. Should you find that the minimum resistance that you measure between pins that are connected by a metal strip is greater than 5 W, you may have a bad breadboard. Very rarely, the metal strips shift in position during shipment. Contact one of the the OpEL GTA immediately and show the GTA the measurement. If the GTA determines that you have a bad board, he will trade your old ANDY board for a new.