June 29, 2010:
New page: v3.1

October 30, 2014:
New page: v4.2

March 17, 2015:
New page: v4.6

Thanks to Andreas for this great  website template! You can find his website here

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 Websites:

Latest Addition:

17.3.15: In which Andrew apologies for Yahoo sending email  to another continent

30.10.14: Lots of new projects added

The Curse of Yahoo Email

I've been busy over the past few months developing a bunch of new designs. A further recent development, quite unknown to me as I'll explain, was the publication of a design of mine for a talking frequency counter in the March 2015 issue of the US amateur radio magazine "QST", published by ARRL.

I submitted that material to QST for consideration about three years ago. You'll forgive me if I didn't give it a lot of attention after all that time. Since I currently live in the Middle East, and ARRL like to send stuff back and forth to authors via snail mail, I warned ARRL editors a number of times about sending letters to me. The postal service is not reliable in this part of the world. No-one seems to believe it, but it's true.

For example, what address do you write on the letter? Fourth sand dune to the left of the brown camel? OK, maybe not. The problems really start, however, with the street names. They are somewhat "variable", shall we say? Some locals call their street by one name, others call it something completely different. Even if they agree on the name, then consider the variations in spelling those Arabic names in English. (Oh, my word!) Finally, and as you would expect, the postal staff are much better at reading Arabic addresses than ones written in English. That's just the start of the problems, but perhaps you begin to get the idea.

Over the past six years, I've probably received perhaps ten letters, not all in (ahem) good condition. The neighbour's brown camel has seen to a couple, I reckon.

So when the ARRL sent me a letter telling me my article had been published in QST, it was a minor miracle that the letter actually got to me. I think it arrived about two months after the article was published. The letter promised they'd be sending me a copy of the magazine. By mail. I'm not holding out a lot of hope for that, but I'm also keeping a pretty watchful eye over that camel next door.

Meanwhile, I was thinking that questions about that design might arrive at my email address My Callsign (at) now that it had been published, but nothing happened.

Eventually, the light dawned, and I realised perhaps something was wrong. So I tested my email. It was then that I discovered that Yahoo's camel had got to it. For some reason, Yahoo had changed my email address from MyCallsign (at) to MyCallsign (at)
See the subtle difference? Took me a while to figure that one out.

Well, of course, Yahoo. Send my email to Australia. Sure, why not. It's got sand. A desert. Yes, camels, too... What the...?

Did Yahoo tell me? Nope. Warnings? No. Looking at my email, I could see a date, which is not all that long ago, when email was arriving correctly and answers were going out just fine too, with the correct email address from my end added automagically, and then....Nix.

Checking around, it seems I was not the only poor soul affected by that Yahoo, er, change. Not by a long shot.

"I'll call Yahoo's Customer Care," I decided. "They'll fix it!" Ah, no. Doesn't seem to exist. Yahoo, perhaps less than helpfully, point almost all such queries and concerns to "the community". Is that something like a group of similarly cursed doomed souls? So, yeah, good luck with that. After looking at a bit of that "community" email traffic, I began to understand why Yahoo may not be the success it once was.

So, rather than attempt to fix something that Yahoo's clearly not much interested in (although I tried, oh, how I tried...), I've simply changed my email address to a new one that's hosted on a commercial-grade email server. You'll see my new email address over to the right on this page. It's in graphical form so I can stay maybe 10 minutes ahead of the spammers.

So, sorry, folks. Really sorry.

Feel free to use that new email address to ask any questions about anything on the website. Just note - I do have a day-job, so sometimes it may take me a few days to answer. And I have to feed that camel. The promised issue of QST may just turn up any day now, and I'd rather it took to the hay than the paper...

Office Mail?

Ah, I can hear someone asking out there: "Why doesn't Andrew simply get his snail mail sent to his office? That's a reliable method in that large Middle Eastern country." Hmmm, let me explain.

I work for a fairly large and quite typical enterprise. Mail arrives for us either directly to the post office box, or to our office building via courier, or by hand. Almost anything serious is by courier or hand. Yes, it is quite normal for someone to send their driver and car with their letter on a two hour round trip drive across the city's nightmare traffic to this building to deliver a letter.

Meanwhile, back in the post office... Post office box mail is collected about once or twice each month by staff in offices like ours. In our case, it's then put in a large (VERY large) sack in an office in the building. Occasionally, a handful of mail will be pulled out and delivered to a few lucky souls, but that's quite unusual. So, if I am expecting mail to the office, I must go to that room periodically and look in the sack. And it's a BIG sack.

Once every couple of years, they seem to tip the sack out and start fresh. Don't ask where the old mail goes. Must be a quantum thing because, as far as I can discover, it's never seen again.

Oh, and if you really think using the courier is a good plan to send and receive mail, well, good luck with that, too. Despite the fact our building is 15 floors high and visible across most of the city, and next to one of the largest universities in the Middle East, courier drivers often report being unable to find the building. But at least they can call me for instructions.

I had one call me
last week. He'd already been given the location (It's also on the corner of two really large and well-known roads in this city) and he had the GPS location of the building accurate to within 50m. But, nope, he couldn't find the building. We had this really interesting Arabic-English phone conversation while he drove around trying to figure out where the office was. His native language was, I think, Urdu. I don't speak Urdu. Sigh.

Anyway, I don't use couriers much for my own mail. I gave up on that a long time ago. Sending a standard letter by courier from here to, say, London or New York costs about US$100. Same cost to send couriered mail from those places to me here too. You might understand why I don't get my parts that way.

Mail a letter at the post office? Mmm. Look, it took a bunch of us three years to actually find the Main Post Office in the city! Post a letter there? Don't ask...

Which all explains why we don't use the mail much in the desert. Camels are way more reliable.

So was email, until Yahoo.

What's on this Website?

Aside from my rants 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).

New Designs Coming Soon...

New projects and designs to be added soon (I hope):

Example image - aligned to the right

  • Some notes about adding a crystal oscillator to my QST talking counter design
  • New LED clock design in an interesting package
  • Homebrewed battery holders (Try to buy a battery holder in the desert!)
  • My version of an LC meter, and
  • Some thoughts on temperature controllers for soldering irons
And there are a few more projects waiting in the pipeline. I've just got to find some more time... 

The Legal Stuff

You use the information 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 adn 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 ZL2PD.

Example image - aligned to the right