CHAPTER 13 ■ SOLDERLESS BREADBOARD SETUPWith the voltage feature of a multimeter, check that battery power is now distributed in the upper and
lower rows (distribution busses) all across the breadboard.
Installing a Power Indicator LED
Recall the LED power indicator circuit you built earlier with alligator-clip jumper leads. Basically, it consisted
of a resistor hooked to positive power and then to an LED. The other end of the LED was connected to
negative power. The LED turned off whenever the battery was disconnected at any point in the loop.
Since you’ve distributed power throughout the board, you can add the power indicator circuit wherever
you’d like. I chose the lower-right corner because there’s just enough space there.
Insert one lead of a 1 kW resistor into any hole that has positive power. Insert the other resistor lead into
a 5-position group (see Figure 13-11).
Figure 13-11. LED power indicator circuit connected to lower bus
In that same 5-position group, insert the anode of a red LED. Note that the LED isn’t receiving the full force
of the battery because power is supplied to the group only through the protective (current limiting) resistor.
Insert the cathode of the red LED into an adjacent 5-position group. Connect the adjacent group to any
hole that has negative power by using a black jumper wire.
The red LED should light when the power switch is turned on. The LED should extinguish when the
power switch is turned off.
Checking Voltages at Certain Points
You should check the voltages of the breadboard power indicator circuit to be assured they are similar to the
same circuit assembled with alligator-clip jumper leads.
Recall that to test voltage at a point, the black multimeter test probe must be connected to negative
power. Since you’ve connected the battery’s negative terminal to the black binding post and to the bottom
row of both upper and lower buses, you can connect the black test probe to any of those locations.
In Figure 13-12, I chose to connect the black test probe to the bottom row of the lower bus. I could have
chosen any hole on the bottom row of the board because they are all connected to negative power.