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?

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.

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.

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.

Some information is described here on this page about solutions to a couple of problems experienced by some builders.

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...

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...

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...

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

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....

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

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.

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.

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...

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:

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....

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.


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 ...

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

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.

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.