This blog is where I share projects I’m working on, discoveries I’m making along the way, and general thoughts of an electronic nature. I’m an electronic engineer, and you can find out more about me on the About page here. Have fun, and I hope you find this notebook helpful and useful!

Gerrit

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Convert Floats to Engineering Notation

A useful utility in the engineer’s software toolbox is to be able to convert a floating point number to engineering format (that is, with an exponent which is a multiple of 3).  You should be able to specify number of significant digits, and possibly a letter suffix for kilo, mega, micro, etc.  In other words, you’d like to … Read more…

Comparing LTspice and Oscilloscope Waveforms

Sometimes you want to see how closely your SPICE simulation matches the real circuit as seen by your scope.  Here is a utility which imports an LTspice waveform and the data from your scope, overlays them, and allows you to slide one back and forth to line them up.  It’s called CompareWaveforms, and here’s what … Read more…

Fitting Equivalent Circuits to Impedance Data

Impedance analyzers like the HP 4194 allow you to model an equivalent circuit to impedance data you measure.  This is often used to determine equivalent component values for a common resonator model such as the circuit shown at left.  Scan the impedance of your resonator around its resonant point, and the 4194 calculates the model components and shows … Read more…

Beautiful HP 4194A Plots and Data

The Hewlett Packard 4194A is a workhorse impedance analyzer, still considered the gold standard by many and in wide use worldwide.  It is an autobalancing bridge, which provides remarkable wide range and accuracy, from 100 Hz to 100 MHz. I’ve had a 4194 for many years and get much use out of it, measuring transformer characteristics, … Read more…

Calculating AC Power

There is often confusion about which quantities to use and how to measure AC power.  I’m talking about power flowing from a source to a load, whether that’s line power, audio, or RF.  I’ll discuss non-sinusoidal waveforms here too. First of all, here’s something you can always rely on: Real power flowing to a load is … Read more…

Arbitrary Phase and Magnitude from I and Q Sum

A sinusoid of arbitrary phase and amplitude relative to a reference sinusoid may be generated if the in-phase (I) and quadrature (Q) components of the reference are available. In other words, the sinusoid may be created from   (the I component) and  (the Q component) by forming the scaled sum  with the proper choice of … Read more…

Alinco DJ-F1T NiMH Battery Charger

I’m as cheap, er, frugal as the next ham radio operator, so I’m loath to throw out my old Alinco DJ-F1T 2-meter handy-talkies just because their old NiCd batteries wore out. New NiMH batteries are available for this venerable radio from various sources, and I ordered a couple from these folks.  The power capacity (mA-h) … Read more…