Tech news spot on ABC Radio

Scammers are a real threat to us all. Australians lost billions of dollars last year. Nightlife Tech Guru Peter Marks, a software developer and technology commentator from Access Informatics, joined Philip Clark on Nightlife to discuss the latest news in technology. https://www.abc.net.au/listen/programs/nightlife/tech-talk-with-peter-marks/104622796 

Rosebud Radiofest most entertaining

Lots of useful parts for sale at good prices. I bought PL-259 crimp connectors for $3 each instead of the much higher prices I see them online. Tempted by one radio but the seller didn't accept my offer. Probably should have stayed until the end but it's a long drive back to Drummond. I did buy a few books and a nifty hot air gun.

It seemed a bit quieter than last year but there was lots to see.

Mostly, it was great to catch up with friends. Here's Peter, VK3YE being sold morse keys by Drew VK3XU:

Andrew, VK3BEK; Ralph VK3ZZC (who purchased yet more test equipment), Dave VK3ASE:

I bought a few books including the excellent "radio handbook" by William Orr. 

I looked it up on Amazon and find that a new copy is on sale for $749!

Jim, VK3ZKK and Judy VK3FJAD were representing the Radio Amateurs Old Timers Club.

As always, a very well organised event. It's marvellous to see the big signs on the roads leading up to the venue.

Tried Apple Vision Pro - a glimpse of the future

The Apple Vision Pro is a product they've been working towards for many years. The software progress has been public, in the form of ARKit, and the hardware in private. It shipped early this year and, while I've read many reviews, it's something I wanted to try myself.

You can book a personal 30 minute demo at Apple stores and it was easy to get an appointment.

The first step is that they put your glasses (if you wear them) in a machine that figures out your prescription. I had mine with me but they preferred to let the machine do it. My sight requires astigmatism correction and the magnetic clip in lenses they came back with seemed good.

There are some new user interface gestures to learn. Basically you "point" at things just by looking at them and "click" by touching your thumb and forefinger. It's hard not to try to point with your fingers at first.

After putting the headset on and adjusting the straps to keep light out the magical thing is when the outside world appears thanks to the high resolution cameras and high resolution screens in front of your eyes. It really looks like you're looking at the world through glass. Perspective seems the same and it's high dynamic range.

The first thing I did, which perhaps puzzled my demonstrator, was turn my head side to side rapidly to test the refresh rate. It's good but not perfect, the scene got a bit choppy.

There's a bit of calibration to do, looking at dots in front of you etc. It worked well.

Then a bunch of demos to run through. 2D photos, 2D video, 3D photos, 3D video and "immersive" photos and video. I have no interest in sport but the 3D video of basketball was quite impressive.

Most iPad apps can be used in a floating window and I looked up my WSPR Watch app in the App Store but it wouldn't let me install it.

The most impressive thing to me was how solidly user interface elements seem anchored in place around the room you're in. You can surround yourself in "windows" and pull or push them away.

The headset is bulky but didn't feel heavy on my head. After wearing it for about 20 minutes it did feel a bit hot and was a bit of a relief to take off. I could certainly imagine wearing one on a flight to privately watch a movie but I think that would be a waste of the technology.

I saw a couple of minor glitches during the demo but overall it was a solid platform.

The jury is still out on the future of spacial computing. One day the big flat screens we put on our desks will seem as dated as the deep CRT screens we used to use.

It was great to try this out. If you have time, take the opportunity. There was zero pressure from the demonstrator to have me buy one. At AU$5,000 and up, I wasn't tempted. If the price comes down to something similar to an 8k monitor they'll sell like hot cakes.

ChatGPT is incredibly useful for electronics calculations

When I wanted to calculate something in the radio shack, I used to google for the formula and then execute it on a scientific calculator. Just now I wanted to know "5dbm as peak to peak voltage across 50 ohms" so I asked ChatGPT which responded very helpfully:

This is really useful. I look forward to having it built in to my phone.

Having said that, this interesting video looking at whether high SWR causes common mode current on coax points out that ChatGPT isn't always correct but is useful.

Hole saw pad PCB construction

I generally use superglued on MePads from QRPme but burn through them at a great rate. Recently I had a go at cutting insulating tracks on PCB with a Dremel cutter wheel. 

I purchased a set of diamond (really?) tipped hole saw bits intending to use them to cut my own pads but this didn't really work as the thickness of the cut is so wide you make a big hole and get a very small pad. 

By using the hole saw to just cut the copper layer I get a nice insulated pad and it's not hard to add extra pads to a circuit under construction. Here's a diode ring modulator currently on the bench:

 MePads are great but it galls me to pay more for postage than the product. I wonder if a PCB manufacturer can make something like them?

Tech news spot on ABC Radio

Peter Marks, software developer and technology commentator from Access Informatics joined Dom Knight with all the latest in tech news. It's been 40 years since Microsoft Excel was developed, touchscreens are out and buttons are back! listen at: 

https://www.abc.net.au/listen/programs/nightlife/nightlife-technology-peter-marks/104564546

HF FM transmitter with Franklin oscillator

Recently I've been working on an AM transmitter for 40m. It occurred to me that FM should be much simpler to produce. I had ordered some varactor diodes recently and first tried to FM a crystal or ceramic resonator. I can't get much deviation and the audio did not sound good.

Then I remembered a post on Soldersmoke about a largely unknown but surprisingly stable oscillator called a Franklin oscillator. It has two transistors and has a very light load on the tuned circuit.  

Rather than the variable supply transistor I fitted a 5V three terminal regulator. Coupled to the tuned circuit is a varactor diode with an electrolytic capacitor through which line audio is inserted. There's a trim pot to set the DC to the diode.

Initial results are quite promising.

The brilliant Charlie Morris, ZL2CTM, has an excellent video on the Franklin oscillator.

Thanks Stephen, VK2BLQ, for the tip.