ZL2PD One-Eyed Frequency Counter
ZL2PD One-Digit Pocket Counter
This webpage contains software and (in a month or two, and with the permission of the magazine's editor) full project related information for anyone interested in building this little frequency counter.

This instrument is a lightweight and remarkably rugged portable frequency counter which operates up to 65 MHz. It uses just one large seven-segment LED display to show a frequency with five digits of resolution (i.e. to the nearest kHz) in a package which can be easily carried in a shirt pocket.

The five digit frequency readout (e.g. 29.876 MHz) is displayed in two sets of three digits, with each digit in the selected set of three numbers shown for about 300mS, followed by a pause of about a second. A “MHz/kHz” button is used to select the required set of three digits, either "2 9. 6" or "8 7 6" respectively.

A second button allows a measured frequency to be held in the counter.

The counter uses an Atmel AT89C2051 microprocessor, an 8051 compatible device, and a 74HC4060 divider as the prescaler. It was described in the May/June 2008 issue of New Zealand's amateur radio magazine "Break-In" .

Break-In is published by NZART, New Zealand's amateur radio organisation. Details about the magazine can be found at www.nzart.org.nz

('Break-In' is a term used in ham radio to describe the method by which an operator sending a message can hear the other party's signal during brief transmission pauses)
Files Available to Download:
Intel HEX file - Clicking on this link will allow you to download a zipped HEX format file (1 kB) for programming an 89C2051 chip for use in this counter
Source File - Clicking on this link will allow you to download a zipped Metalink compatible ASCII TEXT format source file (7 kB) for this counter. This will allow the code to be modified by experienced 8051 programmers who may wish to add more features.
Updates - Clicking on this link will allow you to download a zipped file containing any changes made to the design of this analyser or its software since publication.   (Nothing here at present)
Internal view of the single digit frequency counter with the input socket to the lower left (RCA/phono type) and buttons for Hold and MHz/kHz selection. The single transistor buffer stage is followed by a 74HC4060 divider. The output of this stage is counted by the 89C2051 microprocessor which shows the result on the single seven-segment LED display
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