“Those who hear not the music, think the dancer mad”
Walford Counter Kit

Frequency Counter Kit Construction


Following the successful completion of the Kingsdon Transmitter, Midney Receiver and starting Digital Dabbling I needed a Frequency Counter.

As always a great range of suggestions from the very helpful people on the GQRP group and my local club. This is what Ham Radio is all about.

The suggestions included -

The Following Weeks

Well radio fans, which counter shall I build? The Maplins counter was certainly an "off the shelf" option. But what would I learn? Most of the kits and boards use a PIC processor, entailing either programing the PIC or using the supplied firmware. All rather close to computers. Having already constructed the excellent Midney and Kingsdon Walford kits, the course was clear.

Construction - Session 1 - Supply and Control Parts

I read the detailed instructions! Then divided up the components by their values to check everything is present and to speed assembly. Construction proceeds slowly, Placing the components is a challenge, but I now understand. This is all just a plot to encourage study of the circuit diagrams! It works though, the supply parts are completed and tested, helped no doubt by a glass of San Miguel

Learning Points

Construction - Session 2 - Clock and Shift Register Parts

Construction progressed steadily, until due to a lack of attention I inadvertently put 12v through the 5v out pin! I am now after a HC740390, and the other 5v chip!

Construction - Session 3 - Display Parts

The construction of the display certainly required care and patience, I opted to use computer ribbon cable for the wiring between the display and the main board. This seemed to work well.

Construction - Session 4 - Completion

I had completed the frequency counter kit(!) and was starting to get sensible "Countee" things happening.. when I disconnected the 12v rail and it accidently dragged across the board! Again.
Oh dear.. Oh dear.. Needless to say did no more "Countee" things. Tom and I (Mainly Tom!) checked things through, and this time I seem only to have lost the CD40175, the 5v chip's seem OK.

I am currenty seeking a replacment CD40175!

Walford Counter Kit

Construction - Session 5 - Testing!

Christmas 2004 - I emailed Tim and he suggested that I order the basic replacement chip set, incase any other chips had gone, this seemed like a good plan! a couple of days later it arrived.
Removing the old CD40175 was fiddly. However I am getting used to it! No doubt aided by the Victory HopDevil a part of my Christmas beer.. Err.. "consignment" from Tuckers Maltings The only traditional maltings open to the public, and well worth a visit. But we digress..

After fitting the chip and "very carefully" wiring up the power, time for the first test.. The counter started at 47600 and slowly counted downwards. Progress! Further checking revealed that a segment on the MSD of the display was wired incorrectly, this was corrected. Having no other signal source (Yet) I followed the suggested test procedure and hooked up the onboard 3.275Mhz Crystal Oscillator, to the A and B inputs, a row of zeros displayed. The Add control point was "floating" so it subtracted B from A giving the zeros.. Cool! Then when the Add control point was put to 5 volts (As in the photo) the A and B inputs added. It all works!

I was slightly puzzled by the strange display on powerup but removing and reconnecting the A and B inputs gave the correct results everytime! Plus I have yet to connect the reset line(!) and the decimal point..

Next, a Broadside to celebrate, and another chance to use my favorite Christmas present.

Chip Datasheets

CD4060 14-Stage Ripple Carry Binary Counters

CD40175 Quad Flip-Flop

CD40110 Decade Counter and Decoder Driver

74HC04 Hex Inverter

74HC390 Dual 4-bit decade ripple counters (Divider)

Johnson Counters and Logic Gates