Welcome
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.
What's New?
When
I designed several compact CTCSS encoders in early 2020, I
thought that would be the end of it. But requests for details of my
multitone CTCSS encoder I mentioned briefly in the text have just kept on coming ever since.
I just designed it in passing while designing the simple encoders.Well, I've now documented two versions of my multitone CTCSS encoder. The first uses the same tiny PCB as the basic CTCSS encoders, while the second version features a slightly larger PCB, an improved filter, and a portable battery powered enclosure. Both feature an OLED display. You can find all of the details here.
Designing a reliable compact cost-effective fully-featured software-based CTCSS decoder
represents a serious technical challenge. CTCSS decoders used to be widely
available at modest cost. Now, decoders are getting harder to buy (and more
expensive!) with CTCSS being integrated into almost every new
mobile transceiver and handheld.So is a CTCSS decoder, or a combined decoder/encoder ('dencoder'), of any use to anyone these days? Does anyone want or need one?
A background to designing CTCSS decoders and some possible applications and solutions are discussed here.
Silicon Chip magazine published two more of my designs in their September 2020 issue. Both are illustrated on the cover. The first design is a blinking night-light 'lighthouse', an ideal project for those starting out in the electronics hobby or a grandparent looking for an inexpensive project to build with grandchildren.
The second of my designs is a compact 'shirt pocket' sized battery powered digital audio oscillator using an 8-pin ATtiny85. The design features a standard rotary encoder which uses just one I/Opin on the ATtiny85.
All of the details are available from the Silicon Chip website.
Practical Electronics magazine in UK published one of my designs in their June and July 2020 issues - An AM/FM/CW HF and VHF scanning signal generator.
Previously published in Silicon Chip magazine in 2019, it covers from 100kHz - 50MHz and 70MHz-120MHz, or 150 MHz with reduced output.. Some information is described here on this page about solutions to a couple of problems experienced by some builders.
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....
Previously Added:
My compact digital SWR meter
for QRP (low power) transceivers and transmitters weighs in at just 50
grams. It's 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 provided a ton of help with testing the revised software. Thanks, Bob!
Software is available for the ATtiny45 and ATtiny85 as well as the larger 1.3" OLED displays with their (similar, but different) SH1106 controllers.
My
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:
- Several transceivers (For some reason, these have been mostly other people's designs! Must address that soon...)
- Accessories for these transceivers (DDS VFOs, ATUs, SWR meters, etc )
- (Lots of) Oscillators and test equipment
- Switchmode power supplies
- A temperature-controlled soldering iron, and
- Some family-related designs (An unusual LED clock, an electronic sand-dial timer, a binary thermomenter, a Christmas tree...)
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...
DIY AA and AAA battery holders, and
A truly compact LC meter
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.
