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The entries are in alphabetical order by magazine name and then in chronological sequence.
To obtain a copy of any magazine article contact your local public library or the publisher.


Measuring a component's frequency response. Looks at four common sources of error. Includes a basic set-up for using a calibrated attenuator or "gain set" method of measuring frequency response.
AUDIO AMATEUR 3/1974 [Feb 1975] (v.5#3) pg. 8

Accessory for the Heathkit IM-4100 frequency counter is used to measure capacitance.
AUDIO AMATEUR 4/1980 [Nov 1980] (v.11#4) pg. 50

Calibrating frequency counters using a compact disc player and a test CD.
AUDIO AMATEUR 3/1991 [Aug 1991] (v.22#3) pg. 39

How to interface the Intel 8253 programmable interval counter IC to any microprocessor to make a frequency counter.
BYTE Nov 1977 (v.2#11) pg. 146

Program turns your COSMAC VIP microcomputer into a general-purpose, audio-range decade-frequency counter. Works in the 1 to 11,004 Hz range.
BYTE Feb 1981 (v.6#2) pg. 318

Circuit to compare the frequency of a +5 volt supply to a preset upper and lower limit.
BYTE Jun 1981 (v.6#6) pg. 346

How a CD4040 CMOS 12-stage ripple binary up-counter IC can be used to make a low-cost frequency divider, counter, or frequency meter.
COMPUTERS & ELECTRONICS Mar 1983 (v.21#3) pg. 95

Digital frequency counter uses a Intersil type ICM7208, a companion ICM7207 oscillator chip, and the FND503 readout.
CQ. THE RADIO AMATEUR'S JOURNAL Jun 1980 (v.36#6) pg. 84

Description of two new "counters on a chip" ICs from Intersil. The ICM7216/26 A&B and the ICM7216/26 C&D. Functional schematic is shown for a simple d.c. to 10 MHz counter.
CQ. THE RADIO AMATEUR'S JOURNAL Sep 1980 (v.36#9) pg. 84

Antenna accessories for the ham shack. Part 7. R.F. signal generator, frequency counter, absorption wavemeter, frequency meter, and Lecher wires.
CQ. THE RADIO AMATEUR'S JOURNAL Apr 1983 (v.39#4) pg. 82

Measuring frequency using a DVM (digital voltmeter) and this simple circuit.
CQ. THE RADIO AMATEUR'S JOURNAL Oct 1994 (v.50#10) pg. 50

Build a 100-MHz frequency counter that offers bench top performance in a pocket-sized logic-probe case. Features an 8-digit LED display. Est. cost: $160 (kit).

Build a 1-Hz to 10-MHz frequency counter. Est. cost: $40.

The F/C meter. Measure frequency (1 Hz to 100 kHz) and capacitance (5 picofarad to 1 microfarad) over five ranges. Can also provide a frequency standard or be used as an oscilloscope calibrator, squarewave signal injector, a marker for audio-sweep generators, and a non-contact tachometer. Est. cost: $25 (kit).

Super-simple frequency counter will measure from 1 Hz to 500 kHz with reasonable accuracy. Est. cost: $44 (kit).

Portable 2-MHz digital frequency counter has a resolution of 1 Hz.

Auto-ranging, digital, 50-MHz frequency counter. Est. cost: $47 (kit).

25-MHz frequency counter. Est. cost: $40.

PC-based test bench. Part 2. 100-MHz digital frequency counter, an event/period meter, and a precision capacitance meter. Est. cost: $149 (kit).
ELECTRONICS NOW Jul 1992 (v.63#7) pg. 41

Circuit to detect the presence of a 15-kHz audio signal and then light an LED.
ELECTRONICS NOW Nov 1993 (v.64#11) pg. 8

Time-period adapter. Expand the measuring capabilities of your digital multimeter (DMM) with this easy to build and simple to operate accessory. Allows you to measure a low-frequency waveform accurately.
ELECTRONICS NOW Apr 1996 (v.67#4) pg. 39

Four essential test instruments. DC power supplies, function generators, bench digital multimeters, and frequency counters. An examination of their applications and key features.
ELECTRONICS NOW Aug 1996 (v.67#8) pg. 69

Using the 7107 integrated circuit chip. It is a combination analog-to-digital converter, reference voltage, timing clock, and decoder/driver circuit for 7-segment LED displays. Circuits shown for a digital voltmeter, DC current meter, resistance meter, capacitance meter, frequency meter, etc.
ELECTRONICS NOW Nov 1996 (v.67#11) pg. 55
Correction ELECTRONICS NOW Feb 1997 (v.68#2) pg. 12

Add a digital-frequency counter and display to your equipment (receiver, transmitter, test equipment, ...) using this PIC-based circuit. Est. cost: $50-$60 (kit).
ELECTRONICS NOW Sep 1999 (v.70#9) pg. 41

Frequency probe. Build this simple analog instrument to test the frequency of almost any type of waveform. The probe changes any waveform to a squarewave and converts it to a current that is read out on a standard panel meter.
ELECTRONICS NOW Nov 1999 (v.70#11) pg. 87

IC frequency dividers and counters. Part 1. Advantages, techniques and characteristics.
ELECTRONICS WORLD Dec 1968 (v.80#6) pg. 32

IC frequency dividers and counters. Part 2. Includes simple decade counter using inexpensive IC's.
ELECTRONICS WORLD Jan 1969 (v.81#1) pg. 49

A 50-MHz digital counter has the sensitivity and accuracy necessary to measure citizens band frequencies to the FCC requirements of 0.005 % (+ or -). Est. cost: $400.
ELECTRONICS WORLD Mar 1969 (v.81#3) pg. 40

Frequency meter allows frequency measurements with an inexpensive oscilloscope.
ELECTRONICS WORLD Jul 1969 (v.82#1) pg. 82

Basic frequency measurement methods.
ELEMENTARY ELECTRONICS Mar-Apr 1966 (v.2#1) pg. 33

Make frequency measurements quickly and accurately using an inexpensive oscilloscope and a frequency source like an audio oscillator or signal generator.
ELEMENTARY ELECTRONICS Nov-Dec 1975 (v.15#6) pg. 81

Elementary Electronics basic course in electricity and electronics. The origin, theory and uses of the frequency counter.
ELEMENTARY ELECTRONICS Nov-Dec 1979 (v.19#6) pg. 75

650-MHz amplifying prescaler probe converts a 50 MHz frequency counter to operate at higher frequencies. Est. cost: $50.
HANDS-ON ELECTRONICS Fall 1984 (v.2#2) pg. 66

Frequency counter. Build a 120-MHz (and better) hand-held, battery-powered, frequency only or universal digital counter. Est. cost: $50 to $75.
HANDS-ON ELECTRONICS May-Jun 1986 (v.3#3) pg. 87

CMOS phase-locked loops. Part 2. Practical applications of PLL circuits. Circuits include (1) frequency meter upconverter, (2) frequency-to-voltage converter, (3) frequency synthesis, (4) double sync oscillator, (5) adjustable tone detector, and (6) FM demodulator.
HANDS-ON ELECTRONICS Jan 1987 (v.4#1) pg. 79

Tunable audio-frequency meter circuit that can double as a variable audio-frequency tone decoder.
HANDS-ON ELECTRONICS Nov 1988 (v.5#11) pg. 86

Build a 1 Hz to 10-MHz frequency counter. Est. cost: $40.
HANDS-ON ELECTRONICS Jan 1989 (v.6#1) pg. 59
Added Info POPULAR ELECTRONICS [2] May 1989 (v.6#5) pg. 4

KIMCTR, a KIM-1 frequency counter/timer can be used with any microcomputer with comparable features. A frequency counter is constructed using an LSZ counter integrated circuit which is interfaced to a microcomputer with a hexadecimal display.

Frequency-counter adapter for digital multimeters. Frequency-to-voltage converter enables almost any waveform up to 1 MHz to be read accurately on a DVM or DMM.
MODERN ELECTRONICS [2] Nov 1987 (v.4#11) pg. 16
Added Info MODERN ELECTRONICS [2] Jan 1988 (v.5#1) pg. 7
Added Info MODERN ELECTRONICS [2] May 1988 (v.5#5) pg. 94

Photo-Pulser. A phototachometer adapter for frequency counters. Used to troubleshoot an infrared remote control receiver, determine rpm of a spinning shaft, etc. Est. cost: $30.
MODERN ELECTRONICS [2] Jan 1988 (v.5#1) pg. 32

10-MHz frequency counter can be used with any audio or r-f generator. Has an eight-decade LED display and features automatic decimal-point switching, leading-zero blanking, and a crystal-controlled timebase.
MODERN ELECTRONICS [2] Jun 1988 (v.5#6) pg. 44

A 10-Hz to 2.2-GHz general-purpose frequency counter. Est. cost: $100-$150.
MODERN ELECTRONICS [2] Apr 1989 (v.6#4) pg. 46
Correction MODERN ELECTRONICS [2] Aug 1989 (v.6#8) pg. 7

Making it count. Using a frequency counter requires some basic understanding of the instrument's capabilities and how it can be applied.
MODERN ELECTRONICS [2] May 1989 (v.6#5) pg. 33

Four-mode counter. (1) Frequency counter having a range of 2 HZ to 1 MHz. (2) Measure period of cyclic waveforms. (3) Measure randomly occurring events. (4) Measure width of single occurring positive-going pulses.

Schematic for a simple R-F (radio frequency) meter for use with a CB transceiver.
POPULAR COMMUNICATIONS Dec 1989 (v.8#4) pg. 49

RF coil frequency finder.
POPULAR ELECTRONICS [1] Feb 1964 (v.20#2) pg. 60

Build the electronic frequency meter, an ideal instrument for the accurate measurement of audio and ultrasonic frequencies. This direct reading unit measires from 100 Hz to 100 KHz. Fully transistorized and battery powered. Est. cost: $30.
POPULAR ELECTRONICS [1] May 1967 (v.26#5) pg. 73

Direct readout IC frequency meter. Integrated circuits make possible this frequency meter having 5 ranges covering the spectrum from 5 Hz to 1.0 MHz. Est. cost: $12.
POPULAR ELECTRONICS [1] Oct 1967 (v.27#4) pg. 53

Indicator for setting a frequency meter that uses headphones for a zero beat indication.
POPULAR ELECTRONICS [1] May 1968 (v.28#5) pg. 69

Universal frequency counter. Seven counting ranges from 200 Hz to 2 MHz. Three automatically sequencing time bases, 0.1, 1 and 10 seconds. Est. cost: under $200. Part 1.
POPULAR ELECTRONICS [1] Mar 1969 (v.30#3) pg. 33

Universal frequency counter. Seven counting ranges from 200 Hz to 2 MHz. Three automatically sequencing time bases, 0.1, 1 and 10 seconds. Est. cost: under $200. Part 2.
POPULAR ELECTRONICS [1] Apr 1969 (v.30#4) pg. 41
Correction POPULAR ELECTRONICS [1] Sep 1969 (v.31#3) pg. 110

A digital measurement lab instrument. Part 1. Main frame power supply and readout with 20 MHz frequency counter module.
POPULAR ELECTRONICS [1] Nov 1970 (v.33#5) pg. 51
Added Info POPULAR ELECTRONICS [1] Jan 1971 (v.34#1) pg. 63
Added Info POPULAR ELECTRONICS [1] Jun 1971 (v.34#6) pg. 69
Added Info POPULAR ELECTRONICS [1] Mar 1972 (v.1#3) pg. 60
Correction POPULAR ELECTRONICS [1] May 1972 (v.1#5) pg. 23

Build a 175-MHz prescaler to extend your 20-MHz digital frequency counter to work at 175-MHz. Est. cost: $35.
POPULAR ELECTRONICS [1] Apr 1972 (v.1#4) pg. 53
Correction POPULAR ELECTRONICS [1] Jul 1972 (v.2#1) pg. 89

Tips on attaching a frequency counter to an r-f source to make frequency measurements.
POPULAR ELECTRONICS [1] Oct 1973 (v.4#4) pg. 102

Frequency measuring circuit can test electric power for 60-Hz frequency. Use to test utility or portable generator output.
POPULAR ELECTRONICS [1] Jun 1974 (v.5#6) pg. 24

This front end circuit for a digital multimeter (DMM) will turn it into a frequency counter.
POPULAR ELECTRONICS [1] Oct 1974 (v.6#4) pg. 100

This converter turns a digital frequency counter into a highly accurate digital VOM without modifying the counter. Has four ranges of ac & dc voltage readings (5, 50, 500, 1000) and five ranges of resistance (500 ohms, 5, 50, & 500 kilohms, 5 megohms).
POPULAR ELECTRONICS [1] May 1975 (v.7#5) pg. 27

A low-cost audio-frequency meter. Measures frequency (sine or square waves) from 5 Hz to 50 kHz in four switch selectable ranges. Sensitivity is 0.2 volts rms.
POPULAR ELECTRONICS [1] Jul 1975 (v.8#1) pg. 45

Sophisticated 1-Hz to 1-MHz frequency counter with 3-digit readout uses state-of-the-art CMOS chips. Est. cost: $30.
POPULAR ELECTRONICS [1] Aug 1976 (v.10#2) pg. 48

Frequency-to-voltage converter circuit uses a 555 timer IC.
POPULAR ELECTRONICS [1] Aug 1976 (v.10#2) pg. 75

LED bargraph readouts. Measure voltage, resistance and frequency with a row of lights which show trends (direction) better than meters with needles and less expensively than digital readouts. Circuits for several types of meters shown.
POPULAR ELECTRONICS [1] Sep 1976 (v.10#3) pg. 74
Added Info POPULAR ELECTRONICS [1] Oct 1976 (v.10#4) pg. 8

An analog-to-digital temperature converter. Use your frequency counter to measure temperature to 0.1-degree Centigrade resolution. Range is 0 to 100 degrees. Est. cost: $10.
POPULAR ELECTRONICS [1] Dec 1976 (v.10#6) pg. 62
Correction POPULAR ELECTRONICS [1] Jun 1977 (v.11#6) pg. 6

Digital frequency readout for shortwave receivers. Programmable counters provide digital display of received frequency up to 30 MHz. Est. cost: $110.
POPULAR ELECTRONICS [1] Feb 1977 (v.11#2) pg. 49

Build a 10-Hz to 1-MHz EPUT (events per unit time) meter. An inexpensive frequency counter that can measure sinusoidal and complex waveforms. Features an analog (meter) readout and uses the 60-Hz power line as a calibration reference.
POPULAR ELECTRONICS [1] Mar 1977 (v.11#3) pg. 68
Correction POPULAR ELECTRONICS [1] Jun 1977 (v.11#6) pg. 6

Portable, hand-held frequency counter will count from less than 100 Hz to more than 40 MHz and display the input signals on a six-digit multiplexed LED display. Est. cost: $50.
POPULAR ELECTRONICS [1] Jun 1977 (v.11#6) pg. 64

A look at the MC 14553B 3-decade BCD CMOS counter chip that can be used to make various event and frequency counters.
POPULAR ELECTRONICS [1] Feb 1980 (v.17#2) pg. 98

Circuit for a X100 frequency multiplier or prescaler which simplifies low-frequency measurements and allows them to be measured on most frequency counters.
POPULAR ELECTRONICS [1] Sep 1980 (v.18#3) pg. 128

The F/C meter. A low-cost project that allows you to measure frequencies from 1 Hz to 100 kHz and capacitance from 5 pF to 1 uF over five ranges.
POPULAR ELECTRONICS [2] Jul 1989 (v.6#7) pg. 29

Sub-audio frequency meter. Simple add-on circuit extends the range of your digital-frequency counter into the sub-audio region (below 100 Hz).
POPULAR ELECTRONICS [2] Nov 1989 (v.6#11) pg. 35

Build a budget frequency/events counter that handles everything from 1 Hz to 100 kHz. Various alternatives are provided for triggering, power supply, etc. Est. cost: $80.
POPULAR ELECTRONICS [2] May 1990 (v.7#5) pg. 33
Added Info POPULAR ELECTRONICS [2] Aug 1990 (v.7#8) pg. 4

Simple frequency counter circuit can be used to monitor signal frequencies from 100 Hz to 100 kHz in decade steps.
POPULAR ELECTRONICS [2] Oct 1990 (v.7#10) pg. 23

Digital frequency counter-timer module (Optoelectronics, Inc. Model UTC-150) is described and evaluated. Handles 0.1 Hz to 150 MHz.
POPULAR ELECTRONICS [2] Oct 1990 (v.7#10) pg. 86

Digital electronics course. Introduction to IC counter circuits. Learn how counters count, and how to use those IC's in your circuits.
POPULAR ELECTRONICS [2] Nov 1990 (v.7#11) pg. 71

Super simple frequency counter displays from 1-Hz to 500-kHz on a 6-digit display. Est. cost: $44 (kit).
POPULAR ELECTRONICS [2] Jan 1991 (v.8#1) pg. 41
Added Info POPULAR ELECTRONICS [2] May 1991 (v.8#5) pg. 3

Using digital frequency counters to measure the operating frequency of a radio transmitter.
POPULAR ELECTRONICS [2] Mar 1991 (v.8#3) pg. 84

Op-amp based circuits. (1) One-way voice-activated intercom. (2) Analog audio-frequency meter. (3) Simple audio-power amplifier.
POPULAR ELECTRONICS [2] Apr 1992 (v.9#4) pg. 67

Build a portable 2-MHz frequency counter with a resolution of 1 Hz.
POPULAR ELECTRONICS [2] Jul 1992 (v.9#7) pg. 53

How to use the popular 555 timer IC in practical monostable multivibrator circuits. (1) Fixed-period timer. (2) Relay drivers. (3) Pulse generator. (4) 1-kHz linear-scale analog frequency meter.
POPULAR ELECTRONICS [2] Mar 1993 (v.10#3) pg. 53

Build an auto-ranging, 7-digit, 50-MHz frequency counter.
POPULAR ELECTRONICS [2] Nov 1994 (v.11#11) pg. 33
Correction POPULAR ELECTRONICS [2] Jan 1995 (v.12#1) pg. 4

Build a 25-MHz frequency counter. Est. cost: $40.
POPULAR ELECTRONICS [2] Feb 1995 (v.12#2) pg. 53

Build a frequency response tester for audio components. Displays the frequency response on an oscilloscope. Range is from 20 to 20,000 Hz.
POPULAR ELECTRONICS [2] Mar 1995 (v.12#3) pg. 51

Build a four-mode counter. (1) A frequency counter with a range of 2 Hz to 1 MHz also measures (2) the period of cyclic waveforms, (3) occurance of random events, and (4) width of single occurring positive-going pulses.
POPULAR ELECTRONICS [2] Mar 1996 (v.13#3) pg. 56
Added Info POPULAR ELECTRONICS [2] Aug 1997 (v.14#8) pg. 6

Simplified 3.5-digit frequency counter has four ranges (2000-Hz, 20.00-kHz, 200.0-kHz, and 2.000-MHz) and will work with almost any waveform. Fits into a standard logic-probe-type case.
POPULAR ELECTRONICS [2] Mar 1996 (v.13#3) pg. 67
Added Info POPULAR ELECTRONICS [2] Sep 1996 (v.13#9) pg. 69

DTMF frequency counter lets you test the output signals from a telephone keypad. Est. cost: $16.
POPULAR ELECTRONICS [2] Aug 1997 (v.14#8) pg. 54
Correction POPULAR ELECTRONICS [2] Oct 1997 (v.14#10) pg. 8

Build a CB (citizens band) frequency counter that covers from 5 Hz to 30 MHz. Uses a five-digit LED to indicate what frequency you are using. Est. cost: $60.
RADIO-ELECTRONICS Sep 1977 (v.48#9) pg. 43

Build a portable 30-MHz frequency counter. Unit is powered by four NiCad batteries. Features a 4-digit readout that delivers 6-digit resolution. Est. cost: $40.
RADIO-ELECTRONICS Mar 1978 (v.49#3) pg. 35

Frequency counter in a probe. Part 1. Build this 0 to 750 kHz or 2.5 MHz to 10-Hz digital meter using the IC bricklaying technique.
RADIO-ELECTRONICS Oct 1978 (v.49#10) pg. 67

Frequency counter in a probe. Part 2.
RADIO-ELECTRONICS Nov 1978 (v.49#11) pg. 71

Audio test station. Part 1. A series of articles describing the operation, design and construction of Fidelity Sound's model 101 Audio Test System kit. The unit consists of a power supply, two sine/square/triangle function generators, pulse generator, frequency counter and AC voltmeter. Est. cost: $650 (kit).
RADIO-ELECTRONICS Jan 1979 (v.50#1) pg. 35

Build the OPTO-7000 600-MHz portable frequency counter from a kit. Est. cost: $100.
RADIO-ELECTRONICS Jan 1979 (v.50#1) pg. 39
Correction RADIO-ELECTRONICS Jun 1979 (v.50#6) pg. 6

Audio test station. Part 2. Power supply and timebase circuits.
RADIO-ELECTRONICS Feb 1979 (v.50#2) pg. 45

Audio test station. Part 3. Pulse generator, sweep shaper, and audio sweep generator.
RADIO-ELECTRONICS Mar 1979 (v.50#3) pg. 76

Audio test station. Part 4. Theory of operation and the construction of the voltmeter and digital frequency meter sections.
RADIO-ELECTRONICS May 1979 (v.50#5) pg. 59

Audio test station. Part 5. Step-by-step through the calibration process.
RADIO-ELECTRONICS Jul 1979 (v.50#7) pg. 54

Build this UHF prescaler for your frequency counter. Extend your counter's range as high as 650 MHz. Est. cost: $30.
RADIO-ELECTRONICS Aug 1981 (v.52#8) pg. 64

Frequency-counter preamplifier circuit boosts input signals from mixers, oscillators and IF strips.
RADIO-ELECTRONICS Oct 1981 (v.52#10) pg. 102

Use a 555 IC to build a voltage-to-frequency converter. Use your frequency counter to measure voltages up to 5 volts.
RADIO-ELECTRONICS Jan 1982 (v.53#1) pg. 34

Build this frequency multiplier for your counter. Add low-frequency (10 Hz to 40 kHz) accuracy by inserting this multiplier between test cable and counter. Est. cost: $41.
RADIO-ELECTRONICS Nov 1982 (v.53#11) pg. 43

Build this audio frequency response meter. Use it to tune up amplifiers, tape recorders, etc. Est. cost: $25.
RADIO-ELECTRONICS Jun 1983 (v.54#6) pg. 51

Frequency-boundary detector circuit will tell you whether or not an input signal is within a certain frequency range.
RADIO-ELECTRONICS Jun 1983 (v.54#6) pg. 96

How to use digital panel meters to measure voltage, current, resistance, capacitance, frequency, temperature, etc. Part 2. Temperature and frequency.
RADIO-ELECTRONICS Mar 1984 (v.55#3) pg. 63
Added Info RADIO-ELECTRONICS Jun 1984 (v.55#6) pg. 15

All about frequency counters. What they do and how they do it. Part 1. Basic frequency counters.
RADIO-ELECTRONICS Apr 1986 (v.57#4) pg. 69

All about frequency counters. Part 2. Sophisticated uses of this versatile instrument.
RADIO-ELECTRONICS May 1986 (v.57#5) pg. 71

1.2 GHz frequency counter. Build this high-performance, hand-held frequency counter that can measure from 1 Hz to 1200 MHz with a sensitivity under 25 mV throughout its useful range. Est. cost: $60.
RADIO-ELECTRONICS Jul 1986 (v.57#7) pg. 47, 75, 76

100 MHz frequency counter offers bench top performance in a pocket-sized logic-probe case. Est. cost: $140.
RADIO-ELECTRONICS Feb 1990 (v.61#2) pg. 31, 60

1.6-GHz amplifier/prescaler for use with any high-quality, low-range (up to 50-100 MHz) frequency counter. Est. cost: $100.
RADIO-ELECTRONICS Oct 1990 (v.61#10) pg. 47

Bench top frequency counter project counts input frequency in decades, stores the results in latches, and drives an 8-digit multiplexed LED display.
RADIO-ELECTRONICS Dec 1990 (v.61#12) pg. 33
Added Info RADIO-ELECTRONICS Feb 1991 (v.62#2) pg. 21 (PC-board foil patterns)
Added Info ELECTRONICS NOW Oct 1998 (v.69#10) pg. 5

Turn your PC into a universal frequency counter. Build a frequency-counter board that operates in a Windows environment. Est. cost: $300 (kit). Part 1.
RADIO-ELECTRONICS Feb 1991 (v.62#2) pg. 37

Turn your PC into a universal frequency counter. Part 2.
RADIO-ELECTRONICS Mar 1991 (v.62#3) pg. 43

Sweep/function generator and frequency counter. Produces up to a 2.5-MHz square, triangle, or sine-wave output with a 1 to 20-volt peak-to-peak amplitude and a 20-dB attenuator. Has TTL or CMOS 0.5- to 15-volt peak output as well as a sweep generator and frequency counter that can read up to 150 Mhz. Est. cost: $300. Part 1. Theory of operation.
RADIO-ELECTRONICS Jan 1992 (v.63#1) pg. 35

Sweep/function generator and frequency counter. Part 2. Construction and use.
RADIO-ELECTRONICS Feb 1992 (v.63#2) pg. 53

Low-frequency AC-to-DC converter facilitates the measurement of AC signals with frequencies lower than 20Hz using a digital multimeter.
SPEAKER BUILDER 1/1994 [Jan 1994] (v.15#1) pg. 56
Added Info SPEAKER BUILDER 4/1994 [May 1994] (v.15#4) pg. 50