CHAPTER 26 ■ SMOOTHER, SMALLER, CHEAPER
Spending Money
There were a couple of parts that increased the cost of the robot.
The microcontroller cost only $1 but replaced just one small chip. Oftentimes, a microcontroller
replaces multiple logic chips in a design and thereby can result in immediate and direct savings. In this
case, the microcontroller does allow the robot to swap out the pushbuttons and trimpots as well as the
comparator, so the overall result is still net positive.
The phototransistors are considerably more expensive than the cadmium photocells, which is one
reason why cadmium photocells are still used in low-cost products. To be fair, there are less expensive
phototransistors on the market, and the price I quoted for the cadmium photocells is from a surplus grab
bag that requires hand sorting.
Ever Changing
As you saw in this chapter, surface-mount parts and microcontrollers can reduce the size and cost of robots
while adding functionality. Often, the circuits aren’t that much more complex because software replaces
some of the hardware.
There is nothing wrong with sticking with through-hole parts and proven designs. There is a significant
time cost to researching, selecting, and applying a new part. Most cutting-edge packages are not intended
for use with hobbyist tools. Then again, sometimes it is just fun to try something new (see Figure 26-11).
Figure 26-11. The new-fangled Sandwich fits nicely into a new-fangled container