September 2013 17
QUESTIONS and ANSWERS
■ FIGURE 2.
Re: Beginner’s Question, July 2013:
Someone who was completely new to electronics asked
you what you would recommend to start learning. Coming
from a professional, your first answer was Algebra and to
continue on with Calculus. Russell, I hate math. Almost just
like you, at age 13 my father bought me a "cat whisker"
crystal radio kit; it worked and I was hooked. How could
this tiny radio play into the night every day with no power?
What were those little resistors with the pretty colored
stripes? Then, for Christmas I received a RadioShack
300-in-1 Electronics Kit, and my world changed. I made
myself an electronic siren, a timer, a metronome, an
amplifier, and even a radio transmitter! Almost everything I
know and love about electronics was self taught. It is my
No. 1 hobby; today, I even design and build my own
projects using integrated circuit technology. Plus, of course,
Nuts & Volts is my favorite magazine!
You know what, Russell? I still hate math!
Frank Alberts III
Math is not a requisite, although lack of it may be a
limitation. SPICE is a good tool to learn because it will allow
you to fiddle and tweak much faster and easier than with a
breadboard. I once designed a circuit that worked but
which I was not competent to analyze. I designed and built
an oscilloscope with scrounged parts before I went to
college, so you can do a lot with common sense and high
Re: Jacob's Ladder Circuit, July 2013:
You were right on in identifying the diode on the
primary as a problem. However, recommending higher
frequencies is probably off the mark. The problem is the
turns ratio of these coils requires about 200 volts to
generate adequate spark voltage. In order to get a 200 volt
inductive kick, we have to interrupt a sizable current in the
primary. Since the inductance of the primary limits the rise
time of the current, the 12V must be connected for a
reasonable time to let the current build up.
In ignition systems, this was called the dwell time
which was set by the angle of rotation of the distributer
during which the points made contact. These units tended
to have problems at high RPM in any case, which is why
capacitive discharge — or solid-state — systems became
popular. These units usually incorporated a DC-DC converter
to generate about 200 VDC which was then switched onto
the primary instead of the 12V in the circuit in question.
This provided a faster rise time and thus sufficient current
to generate a hotter spark. I would thus recommend the
questioner to use a LOWER frequency or use a DC-DC
converter to get strong sparks. At 2,000 RPM, an eight-cylinder engine only fires a spark about 133 times per
second, so 200-400 Hz would be close to what the coil is
Thanks for writing; you are so right! Why didn't I think