Steve Jobs and Heathkit

James, WL7FC/VE3ELI, sent us this clip from a Macleans article. Thanks James.

"His dad, though, was not his only early influence. In those days, the neighbourhoods of Silicon Valley were crawling with techies and engineers conducting cutting-edge work for firms like Hewlett-Packard and the Shockley Semiconductor Company. One of them was Larry Lang, who lived a few doors down from the Jobs house. Steve spent almost as much time in Lang’s garage as his own, tinkering with electronic equipment and assembling “Heathkits”: mail-order products such as amateur radios and receivers that took many hours—and much patience—to put together. Jobs would later say that those Heathkits helped him realize that everyday appliances, like the television in his living room, were not “magical” creations. “It gave [me] a tremendous level of self-confidence, that through exploration and learning one could understand seemingly very complex things in one’s environment,” he said. “My childhood was very fortunate in that way.”"

http://www2.macleans.ca/2011/10/17/thinking-different/

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Oh No! Short Circuit Danger with Anodized Heat Sinks?

Our friend Brent out in Minneapolis sent me some pre-Halloween HB frights yesterday. I'm still concerned. Am I living dangerously with my anodized but collector-connected heat sinks glued to the ground plane?
What say the HB gurus?

--- On Tue, 10/18/11, KD0GLS wrote:

From: KD0GLS Subject: Re: JBOT Amp
To: "Bill Meara"
Date: Tuesday, October 18, 2011, 9:38 PM

Bill,

Well, it is nearly Halloween, but it wasn't my intention to frighten you!

I think it's hard to argue with the fact that it works as-is. The heatsinks you bought look like common anodized aluminum to me. Out of curiosity I dug a couple of similar ones out of my parts bins and measured them. I found exactly what you did - wide open on the surface, and, not surprisingly, a dead short just underneath. I've always assumed that anodize finish was metallic and conductive, but now I know otherwise. I like to learn at least one new thing each day, so thanks for providing today's opportunity!

The clearances are no doubt small, but I think with the low voltages present in your circuit you'll probably be fine. The only potential problem might be if movement or vibration might someday break through that coating. I'd certainly recommend a fuse in the power supply line if you don't already have one.

Anyway, it looks great sitting there in the middle of your old rig. It's inspiring.

Brent

On Oct 18, 2011, at 19:42, Bill Meara wrote:

Brent: You scared me with your question but I think what I did is OK. Maybe. I looked more carefully at the clip on heat sinks I bought. They are covered with a non-conductive coating, but f I scratch them up a bit I can reach the conducting part. So i guess you just have to treat them gently if you intend (as I did) to super-glue them to the PC board. I notice that Farhan did the same thing (see his JBOT page) so I guess I'm OK. I put some heat sink compound in there too. And then there is the super glue. I have no short circuits from the collectors. I guess I could have used a Dremmel to isolate the copper just below the transistors. Or I could have put some mica between the heat sinks and the boards.

The sinks are deeper than the transistors, so there is no direct contact between the top of the transistor and the PC board.

What do you think?
--- On Tue, 10/18/11, KD0GLS wrote:

From: KD0GLS >
Subject: JBOT Amp
To: "Meara Bill" >
Date: Tuesday, October 18, 2011, 5:27 PM

Bill,

The amp looks mighty FB, and maybe I should try it as well. But I'm curious how you've insulated the collectors of all those transistors from the ground plane. From the picture, it looks like all of the metal heat sinks are sitting right on the ground plane copper.

.73,

Brent, KD0GLS, Minneapolis

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My JBOT 5 Watt Linear (Farhan's Design)

There it is -- my version of Farhan's JBOT 5 watt linear amplifier. JBOT stands for "Just a Bunch of Transistors." But I think Farhan is being modest. I really like the design, especially the effort to make this something that hams around the world can reproduce from readily available parts. For example, Farhan's original version used TV balun cores for the transformers. I didn't have any of those around, but I found three "mystery spec" binocular cores in my junk box. They seem to be working just fine. (I tested them a bit: Farhan had written that FT 37-43 cores would work. T1 has seven turns trifilar. Seven turns on my mystery cores yielded 13uH. On an FT 37-43 core 7 turns yields around 20 uH. Close enough -- these are, after all, broadband transformers.)

Note how closely my build follows Farhan's schematic (which you can see in the background). When building this circuit, I just kept Farhan's web page on my computer screen, and scrolled up and down from his schematic to the photo of his version.

This is the first linear amplifier that worked the first time I powered it up. It didn't release any smoke, or leave transistor burn tattoos on fingers, or try to be a 14MHz oscillator.

This version is going into my Azores-built 17 meter DSB transceiver. See how nice it fits:
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My JBOT passes the Smoke Test

Over the weekend I built my first version of Farhan's JBOT. I really enjoyed building it. I soldered in the last connections this morning and I am happy to report that it passed the smoke test. More info (and a picture) tomorrow. Thanks Farhan!

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Bringing some Knack into Astro-Photography

I've been meaning to do this for a long time. It is a neat little project that allows for a quick and satisfying mixture of electronics and astronomy. It has been described on the web many times: Take an old web cam (preferably one of the old eyeball-looking devices) and remove the lens (I found it very cool to expose the charge coupled device).
Take a plastic 35 mm film container (hurry, while supplies last!) and chop off the bottom. Tape the container to the sans-lens webcam. Here's the fun part: Insert 35 mm container and webcam into the focuser of your telescope. Bring laptop out to the telescope and take digital pictures with your telescope.
I used Billy's old Asus eeepc and a very simple program called Cheese. (There has got to be something better for this kind of work.) But my results were very good. Last night I got images of Jupter and two of its moons. This morning I got some great shots of our moon.
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SolderSmoke: Engineering Site of the Day on EE Web!

Dilbert would be so proud! In spite of my Bachelor of Arts Degree, yesterday the SolderSmoke blog was named Engineering Site of the Day by EE Web. I'm especially pleased that the Sputnik rig of the G3XBM team was the featured photo. Check it out:

http://www.eeweb.com/websites/solder-smoke-daily-news

http://www.eeweb.com/

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics"http://soldersmoke.com/book.htmOur coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmokeOur Book Store: http://astore.amazon.com/contracross-20

Can we put a Sputnik signal back in space for $300?

This article from Hack-a-Day caught my eye:
http://hackaday.com/2011/10/11/send-a-satellite-into-space-for-300/
We just make the antenna a bit longer and put it on 20 MHz. Or for a shorter antenna, 40 MHz.
Bert and the fellows out at UVA are going to take care of the whole SETI thing (Jerry, NR5A, was in the lead on this -- he started the SolderSmoke SETI-AT-HOME group). But we'll need some additional volunteers to cover the Low Earth Orbit portion of the SolderSmoke Space Program. And of course we have to come up with the 300 bucks.

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