FreqShow™ Function Generator Frequency Display

FreqShow Function Generator Frequency Display direct-mount to terminalsThe FreqShow Function Generator Frequency Display offers the following features:

  • Accurate display of frequencies from 2 Hz to ~960 kHz  
  • Displays tenths below 300 Hz
  • Uses period measurement below 1 kHz, for better accuracy
  • Operates from 3-4.5 volts DC
  • Low power operation gives long battery life
  • Automatically turns on and off with input signal
  • Kit w/pc board available for easy implementation
  • Available in several configurations - pick the one that's best for you

Specifications of the FreqShow Function Generator Frequency Display:

Input signal required for FreqShow:

  • No comparator installed: 3V Pk-Pk square or pulse waveform
  • With comparator installed: >100 mV RMS sine wave or > 200mV Pk-Pk square wave or pulse waveform

FreqShow Function Generator Frequency Display connection using cableMeasurement accuracy of FreqShow:

Frequency Accuracy
2 Hz - 300 Hz 0.2 Hz
300 Hz - 20 kHz 1 Hz
20 kHz - 50 kHz 3 Hz
50 kHz - 100 kHz 6 Hz
100 kHz - 200 kHz 12 Hz
200 kHz - 400 kHz 24 Hz
400 kHz - 800 kHz 48 Hz

These figures are based on maximum crystal frequency error.  Typical performance will be better.

Standby current: With comparator, 34 μA; without comparator, < 1 μA

Operating current: 2-5 mA, depending on supply voltage applied.

FreqShow Function Generator Frequency Display circuit boardNow you can see exactly what frequency your function or audio generator is set to.  Great for speaker design or audio work.  Based on an 18-pin Microchip® PIC 16LF627A CMOS microcontroller.  Available either with or without input comparator circuit.  Without the comparator, the FreqShow will accept either a square or pulse waveform, with amplitude of about 3V Pk-Pk.  This should suffice for many applications.  If you need more flexibility, add the optional comparator and related components, to allow feeding in lower amplitude and sinusoidal signals.

Photo at right shows populated FreqShow board, with optional comparator circuit installed.  Small, surface mounted comparator is just to the left of the DIP MCU chip. Banana plugs at left are input terminals, and are spaced 3/4" apart to connect to generators with vertical banana jacks on the right edge of the front panel, such as the Heathkit IG-5218 or IG-18.  If your generator has a different configuration, don't order the banana plugs and just use a short length of shielded cable to connect to the pc board eyelets.  Board dimensions: 2.5" x 1.3". 

FreqShow Function Generator Frequency Display circuit board with LCD module

Photo at left shows FreqShow pc board with standard 1x16 LCD module connected, and 3-AAA battery holder mounted underneath.  You can also use a 3-4.5VDC AC adapter.

FreqShow prices:

FreqShow DIY Kit - Chip and pc board only - $15.00 (chip is programmed, with code protect bit set)

FreqShow Basic Kit - pc board and kit of components, no comparator, no banana plugs and no battery holder.  Includes LCD module. - $29.95

FreqShow banana plugs (two pieces) - $2.50

FreqShow battery holder - $1.50

FreqShow comparator circuit parts - $2.50 - Note: Soldering the SOT-23-5 comparator will require a fine-tipped soldering iron, good eyes, possibly some sort of magnifying lamp, and a steady hand.  The comparator circuit is not required if you have an adjustable-amplitude square wave signal available.

FreqShow comparator (mounted) circuit parts - Must be ordered with Basic kit or DIY kit, comparator chip only comes pre-soldered to FreqShow pc board -$4.50

Please download FreqShow assembly instructions, FreqShow schematic diagram, FreqShow parts list, and FreqShow parts placement

Note: All parts needed to populate pc board, except the FreqShow chip can be purchased at Most of the parts can also be purchased at Of course, the easiest way to get going is to purchase one of our kits.

DISCLAIMER: I take no responsibility whatsoever for the use and/or implementation thereof, or the misuse leading to damage to equipment, property, or life, caused by the above circuits.



Copyright © 2007-2013 by All rights reserved.