More to come...

Who is ZL2PD?

For anyone remotely interested in the person behind this website, a few more details can be found here.

Email ZL2PD?

Links to other websites:

Logging the Changes:

27.4.20: Added NiteOwl Torch and CTCSS Encoders

31.1.20: Added smaller 64x32 OLED equipped SugarCube VFO

6.12.19: Added enhanced software for the SugarCube VFO/BFO

10.11.19: Added the portable keypad Si5351a test generator.

10.7.19: The miniature SugarCube VFO is added to the website.

30.05.19: Added details about my AM/FM/CW scanning signal generator published in Silicon Chip magazine.

5.04.19: Added tuning lock function to Single Band si5351a VFO project.

27.02.19: Updated and improved software for SWR Meter project.

17.11.18: Added PVM, VFO PCB, I2C LCD mods, uBitx mic, MKARS80 VFO, plus minor changes.

12.8.18: Small project update, minor changes.

19.11.16: Some minor maintenance updates and corrections here and there.

20.8.16: Updated several pages, added new Nighthawk, aviation rx, xtal checker, cardboard LC meter and 8-digit counter box projects.

7.3.16: Added source code files and a bit more info to the multi-feature si5351 VFO, and added details of a second si5351 VFO

28.2.16: The ZL2PD si5351a VFO, GPS frequency reference, Li-Ion battery monitor, CS2000 signal generator were added to the website

15.9.15: The OBD-2 speedometer and a digital QRP SWR meter were added to the website

18.6.15: Soldering stations, four dot clock and soldering iron cleaner added

17.3.15: In which Andrew described how Yahoo sent his email to another continent!!

30.10.14: Lots of new projects added


Welcome to my website. This site describes some equipment and circuits that I've designed and built. Many are related to amateur radio, but there are some test equipment projects, kit builds, and other things that I have designed. I'd like to claim it's all been done to a plan, but that's not really the case. Development of this material tends to follow a fairly random process around here.

I usually have a number of large and small projects ready to be published. All I have to do is find the time to write them up for the website. So check back here periodically to see the latest additions.

What's New?

CTCSS is becoming quite commonplace now in ham radio , just as its been for many decades in professional two-way radio systems.

Having looked for a suitably small and cheap CTCSS encoder to help restore several old VHF transceivers around here, I ended up designing three different high performance CTCSS encoders. They all share the same tiny single-sided PCB.

You can read more about two of these CTCSS encoders here...

We've had some of our extended family staying with us during the COVID-19 crisis lockdown here in New Zealand. Our eldest grandson needed a light for bedtime reading to avoid waking up his younger brother.

I had an old NiteOwlTM gathering dust at the back of a shelf. Some basic design issues led to its rejection a decade earlier. But where there's a need, there's a way!

I converted this old near-useless incandescent reading torch into a highly efficient LED torch. You can read more about it here...

If you are REALLY squeezed for space in your design, here's the latest addition to the Sugarcube VFO family. Following a request for an even smaller display, I've now added a version for the tiny 0.49" 64x32 pixel OLED displays. All of the features, including user-programmable settings, are retained.

The dual-band capable SugarCube software all still runs inside the 8k memory of the little 8-pin Atmel ATtiny85.
All of the details of this version can be found here...

I've just developed new software for the SugarCube VFO, a Si5351a based VFO with dual VFOs and quadrature outputs. Not only have I added dual BFOs and improved tuning, but thanks to a suggestion from Eric, ZL2BMI, I've added user parameter programming. And all of this still fits (just!) inside the 8k memory of the little 8-pin Atmel ATtiny85. Cheap, easy to build and use.

The details about the updated software for the SugarCube VFO is here....

This handheld compact portable 3-output HF/VHF Si5351a RF test oscillator started out as a basic Si5351a software test platform but it quickly grew as features were added. The choice of keypad and tuning knob make it easy to use.
Powered by a single 18650 Li-ion cell and recharged from a standard USB charger, its low power consumption allows it to operate for several months of intermittent use before needing recharging. It weighs just 170 grams (6 ounces).
It doesn't have an attenuator or the modulation features on my all-mode Silicon Chip RF signal generator (See below). However, it can generate AM modulation!
You can read about it here....

I've developed what I think is the smallest Si5351a VFO complete with a fully functional OLED display. My SugarCube VFO measures just 20 x 20 x 12mm excluding the modest 23mm (0.91") OLED graphic display, encoder and pushbuttons. It features dual VFOs with quadrature outputs, plus a BFO/CIO output, operation to nearly 300MHz, and a neat bright clear frequency display to 1Hz. I describe a VHF FM receiver application, too.

Parts cost? Less than $US10. You'll find all the details about my little SugarCube VFO here....

Silicon Chip magazine have just published one of my latest projects - An AM/FM/CW HF and VHF scanning signal generator. It's a compact unit able to carry out all sorts of useful tasks on the workshop bench. The June 2019 issue described the circuit and features. The July 2019 issue describes the construction.

Unlike most projects described here on my website, all of the details for this design are only available from the two Silicon Chip magazines or by downloads from their website. 
Some of the specifications, however, are described here on my website.

Previously Added:

After a request from some users, I've added a new feature to the compact single band si5351a VFO project - A tuning lock function. It's particularly aimed at those using the VFO in mobile, portable and QRP applications. A  small 'lock' icon appears on the LCD when this feature is being used.

Details can be found at the end of the page describing this compact little si5351a VFO.

I have also recently updated the software for my compact digital SWR meter for QRP (low power) transceivers and transmitters. It's a tiny 50 gram device powered from a single AAA battery and uses a bright, easy to read, OLED graphics display.

Some new 0.96" OLED displays didn't work correctly with the original software.  Bob ZS6RZ brought this to my attention, and he also provided a ton of help with testing the revised software. Thanks, Bob!

I've also added software to allow either the ATtiny45 and
ATtiny85 to be used in this design, and I've also  added a new version to allow the use of the latest larger 1.3" OLED displays with their (similar, but different) SH1106 controllers.

PkDVMMy si5351a VFO designs have proven to be incredibly popular. There are kits for my designs all over the internet, with few, if any, crediting me, of course.

To help you build the single band VFO/BFO, I've designed a new
PCB for the single band VFO/BFO. You can use either of the Midas I2C LCDs or the new larger cheap compatible Chinese I2C LCD noted above. You can find the layout here for your personal use only. Commercial/kit use? Email me.

I finally got some time to build my MKARS-80 80m SSB kit transceiver which I purchased some years ago. It used a PIC as a frequency counter to control the analog VFO using the 'huff and puff' method.

Naturally, I decided to upgrade it with a new version of my single band si5351a VFO/BFO. This version uses a cheap Arduino Nano along with the kit's standard 16x2 LCD. My design features
selectable tuning steps, an S-meter and RIT. (More features might be added later...) It's also still in the rough prototype stage but the details of the new design are here...

The Nighthawk 40m CW transceiver. This tiny 10W-capable transceiver is a SW-40+ clone kit available from China. It arrived after a mix-up with my order for an SSB kit. I built it anyway. But then nothing worked. Nothing.

Fortunately, I've managed to fix all of the (many) design errors in this kit. I'm really delighted to have it running. The whole story is here...

This photo shows an electrically heated towel rail. I've designed an AC delay timer for mine. It saves power and avoids the need to nag my family members about turning it off every morning. I know - A 'First World' problem.
It is a solution which may have other applications where switching AC loads is required. It uses one of the 8-pin Atmel processors, The details can be found here...

Other Popular ZL2PD Designs:

This is my compact aviation band receiver. I added a channel-based control board to a widely available aviation band receiver kit. Then I packaged it in an unusually shaped 3D-printed enclosure to make it look more interesting. Even the knobs are printed.

Inside the box, an ATtiny84 generates the DC tuning voltage for the varicap on each of 10 programmable channels using an unusually fast 16-bit DAC. The ATtiny also drives a small 7-segment LED display to show the channel number. A single button  select any of 10 programmable channels. All the details are here....

My si5351 dual output VFO/BFO has more features than I can list here, and remains very popular. Over 3,000 downloads of the software now! It uses a Nokia 5110/3310 graphics LCD and it covers all of the usual amateur radio bands. Add more if you wish. The VFO's low power consumption (Just 30mA at 3.3V) makes it suitable for QRP, and it's cheap to build. The details are here...    

For those wanting a kit, there is one still available from RV3YF. The original kit he sold (without crediting me in any way for the hardware design or the software) is based the kit pictured above. My prototype does not look anything like as nice.

And thanks to Cristi YO3FLR, there's a PCB layout available in the Download section on my VFO's webpage.

My second single band si5351 dual output VFO/BFO also remains popular. It uses fewer than 20 parts including an 8-pin ATtiny85 and an I2C alphanumeric LCD display. An S-meter/RF power meter display is built-in too.  Same low power consumption. And, yes, the Bascom source code software is all available as a free download. So now, you have a choice of si5351 VFOs on my website. The details are here...

Here are the details of an earlier design for a compact digital RF signal generator using a Cirrus Logic CS2000 chip. It's compact, with everything inside a small 3D-printed case. It generates a 3.3V squarewave output from 1.5 to 160MHz (although the specs on that chip claim it is limited to 75MHz) and draws less than 20mA from a 4 - 15V DC supply.

It's really the result of a tale of woe and misfortune, but the circuit works... More details here.

How to Navigate the ZL2PD Website

You'll find the complete list of these designs down the left hand side of this page. Simple 'click-on-em' buttons will lead you to each design. Schematics and other drawings are to be found all over the site, as are photos. Want to see the details close-up? Then just "right-click" on the image or schematic or whatever with your mouse. Chances are, you'll now be able to see much more detail. And you can download it too, if you wish. 

To date, the details and designs here on my website include:

Elsewhere on the ZL2PD website ...

A suite of three different designs for temperature controlled soldering stations, with a detailed design for the most compact unit. It uses a single 8-pin ATtiny25 microcontroller and not much else, and it is packaged in a compact 3D-printed enclosure, also of my own design.

(Right-click the image for a closer look or visit my web page)

For those looking for something a little different, here is a Four Dot Clock which uses just four cheap LEDs (Four dots of light, if you will) to display the time. It's surprisingly accurate. I only adjust it now about once every six months.

More interestingly, perhaps, is the fact that, unlike most clock designs you might have seen, this one does not require another chip to actually do the timekeeping. The clock's ATtiny45 does all that, and more.

And then there's this accessory for the temperature controlled soldering iron I mentioned earlier. It's a tip cleaner accessory using an easy to obtain item from the supermarket, and printed on a 3D printer.

Of course, all of the other designs are still available to browse and build, each listed over to the left in the index. Help yourself!

New Designs... Well...

Example image - aligned to the right

I think I'll give up predicting what will appear here next. Stuff on my list includes:  

A model train controller with sound effects (Not for me, it's for my grandsons, really!)

An interesting HF SSB receiver with a few differences

DIY AA and AAA battery holders, and

A truly compact LC meter

And there are some other projects still waiting in the pipeline. 

Stay tuned... 

The Legal Stuff

You use the information published on these web pages at your own risk!

You may use the information provided here for personal or educational purposes but you may not reproduce it in any form or use this information for any commercial purpose without first obtaining written permission from the copyright holder.

There is no warranty or guarantee, either expressed or implied, covering any information of any kind which may be available from this website or any correspondence associated with this information, or that designs and information provided on this website are free from patent or intellectual property rights of the author or third parties.

Should the information contained on this website be used by any party, that party shall by using the information provided be deemed to take complete responsibility for all risks and liabilities associated with its use and hold the author of this website harmless in the event of any claim, loss, liability or expense associated with any such use.

The rights of copyright over the contents of this website, unless otherwise noted, are claimed by Andrew Woodfield ZL2PD.

Example image - aligned to the right