J
John Larkin
- Jan 1, 1970
- 0
There are times when it is impossible to know what a circuit will do
without breadboarding and modification. For example, I once designed
a system that measured hydrocarbons in exhaust gasses by injecting them
into a Hydrogen-Oxygen flame that contained two gold plated electrodes,
applying 1,000 volts across the electrodes, and measured the resulting
microamp current. I didn't know how many stages of filtering I would
need to handle turbulance and still meet the response spec until I did
a handwired prototype and took some measurements.
True. Sometimes we breadboard a small circuit, like an oscillator or a
GaAs fet switch, or we lay out a little board to test a part when the
datasheet isn't clear or entirely believable. For example, we use a
lot of microwave parts in the time domain, where there's little or no
data. But there's no point in breadboarding an entire product, or even
part of one, when the elements are understood and when the datasheets
are clear.
Straightforward analog and digital and uP circuits will just work if
you're careful. Breadboarding is a pernicious habit that encourages
sloppy thinking and can let a lot of bugs and marginal designs sneak
through to production. The Space Shuttle took off under full power,
with a full crew, and flew to orbit on its first powered flight. The
A380 took off and flew at altitude for hours, first time off the
ground.
John