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ARRL Products: Circuit Design (More) Digital Signal Processing Technology -- Essentials of the Communications Revolution. An understandable presentation and reference on DSP in contemporary communications technology. Do-It-Yourself Circuitbuilding for Dummies -- A fun and easy way to start building circuits for your projects! Experimental Methods in RF Design -- Immerse yourself in the communications experience by building equipment that contributes to understanding basic concepts and circuits. Discrete-Signal Analysis and Design -- A clear, step-by-step approach to practical uses of discrete-signal analysis and design, especially for communications and radio engineers. ARRL's Vintage Radio -- Articles about the lure of vintage Amateur Radio gear.

In the Integrated Timer experiment in "Hands-On Radio" (Jun 2003 QST, page 59), the actions of the set and reset functions of the flip-flop are reversed. Correctly stated, when the set input (trigger comparator output) changes from low to high, Q goes low. When reset (threshold comparator output) changes from low to high, Q goes high.--Dan Ferreira, N1BMA

In "The Protector" schematic (Jun 2003 QST, Figure 1, page 56), resistor R13 (10 k ) was omitted. It should be in series with pin 2 of U2A (LM358) after the junction of R11, R12 and C3.--Arnaldo Drummond, PY5AQ