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:

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 built. I'd like to claim it's all been done to a plan, but that's not the case. It tends to be pretty random around here.

In short, you can never tell what's going to appear here next!

Plans ... and what actually happens around here

My long-running job in the Middle East came to an end in December 2016. At the time, our first thoughts were that we would just move back to New Zealand, but things didn't turn out that way. That 'plan' turned into eight months of travel by air, sea, train and car. (Don't ask!) When we finally returned, getting everything sorted out in our home in New Zealand after we had been away for so many years took way more time and effort than I could have imagined. As a further distraction, consulting work kept coming along. That's dragged me away from home fairly regularly, much of which has required me to work in that client's country for most of this year. 

So much for plans.

What's New?

I have developed a number of new projects over the last 18 months or so. These include:

An AC delay timer for my bathroom heated towel rail. I designed it to save power and to avoid nagging my family members routinely about turning off such appliances. I know - A 'First World' problem.

Regardless, this design is a solution which may have other applications where switching AC loads is required. The details can be found here...

PkDVMA peak-hold LED digital voltmeter. Yes, I know it looks like one of those low cost Chinese modules. My version provides a "peak-hold" feature which I wanted for my lead-acid battery charger. It also has better mounting tabs. My charger automatically turns off when charging is complete and I wanted to know the end-of-charge voltage. Interestingly, it cost me less than those Chinese made modules. How amazing is that! More details are here...

PkDVMI've added some details about using a low cost I2C LCD from China with my single band si5351 dual output VFO/BFO. It's a larger LCD than the original Midas LCD from UK and it has a few more pins.

As it turned out, it was not too difficult to make it work with my original software.
(The actual display looks much better than this picture suggests) Just a few minor connection changes are required. The details are here...

PkDVMMy si5351a VFO designs have proven to be incredibly popular. There are kits for my designs all over the internet (none of them 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 original 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...

Previously Added:

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...

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....

Other Popular ZL2PD Designs:

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.

This is a compact digital SWR meter
for QRP (low power) transceivers and transmitters. It's compact, lightweight, powered by a single AAA battery. It uses a super-bright and easy to read OLED graphics display.

Did I mention it's small? And weighs just 50g ?

More designs coming up soon, I hope.

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. 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:

And there are some new designs, just added. See below...

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 the 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!

What else is on this website?

Aside from a page chattering on a bit about Yahoo and mail, my website describes a variety of projects related to my hobbies of amateur radio and electronics. These include circuit diagrams, descriptions of how they work and what they do, PCB layouts (sometimes), construction details, and software for designs which use microprocessors or microcontrollers.

For the record, the microprocessor designs here use the AVR chips including the ATtiny15, ATtiny25, ATtiny45 and ATtiny85, ATtiny2313, ATtiny26, ATmega8, as well as some earlier designs which use 8051 processors including the 80C552, 80C751, 80C51, 80C52, AT89C1051, AT89C2051, and AT89C4051, and so on. Almost all of my 8051 software is written in assembler while the AVR code is a mix of assembler and BASCOM (Basic).

Example image - aligned to the right

New Designs... Well...

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!)

A couple of signal generators, with some unusual features (of course!)

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 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