Podcasting since 2005! Listen to Latest SolderSmoke
Sunday, November 27, 2011
30% off on SolderSmoke, The Book. Cyber-Monday Sale. November 28
Our book: "SolderSmoke -- Global Adventures in Wireless Electronics"
http://soldersmoke.com/book.htm
Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke
Our Book Store: http://astore.amazon.com/contracross-20
Labels:
book
Saturday, November 26, 2011
A Re-balanced Modulator for my Re-cycled Rig
My effort to bring my Azorean 17 meter DSB rig back to life continues. This is proving to be harder than I thought. I'm still taming my version the JBOT amp. It still seems to break into oscillation -- I think the oscillation freq is around 1 MHz. But I am making progress.
I had to go back and work on the balance modulator circuit. I really like the simple two diode singly balanced mixer circuit. But my original Azorean board had, like the oscillator board, been through a few too many rounds of modification and repair. I decided to start over. See above. I even came up with my own little innovation on this circuit. Doug DeMaw's original design called for a 100 ohm pot at the junction of the two diodes, with the signal coming off the tap. You adjust the pot to balance the circuit and null out the carrier. But I didn't have a 100 ohm pot. Lots of 1K controls were available, so I put in two 50 ohm resistors in place of the pot, then put the 1k pot between the diodes, with the tap to ground. This balances things out nicely. See below.
I hope to get a podcast out next week, but I've been suffering from a nasty headcold that would have introduced all kinds of weird audio effects.
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
Saturday, November 19, 2011
The Bar of King Arduino
I'm not sure what I would do with an Arduino, but articles like this definitely make me want one! Here's one passage:
To make the board, the group had a specific, student-friendly price as their goal: $30. "It had to be the equivalent of going out to dinner at a pizza place," Banzi says. They also wanted to make it quirky, something that would stand out and be cool-looking to erudite geeks. If other boards were often green, they’d make theirs blue; while some manufacturers economized on input and output pins, they’d add plenty to their board. As a final touch, they added a little map of Italy on the back of the board. "A lot of the design choices are weird for a real engineer," Banzi says with a knowing laugh, "but I’m not a real engineer, so I did it in a silly way!"
Here's the article. Note the origin of the name of the device.
http://spectrum.ieee.org/geek-life/hands-on/the-making-of-arduino/0
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
To make the board, the group had a specific, student-friendly price as their goal: $30. "It had to be the equivalent of going out to dinner at a pizza place," Banzi says. They also wanted to make it quirky, something that would stand out and be cool-looking to erudite geeks. If other boards were often green, they’d make theirs blue; while some manufacturers economized on input and output pins, they’d add plenty to their board. As a final touch, they added a little map of Italy on the back of the board. "A lot of the design choices are weird for a real engineer," Banzi says with a knowing laugh, "but I’m not a real engineer, so I did it in a silly way!"
Here's the article. Note the origin of the name of the device.
http://spectrum.ieee.org/geek-life/hands-on/the-making-of-arduino/0
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
Friday, November 18, 2011
Steve Smith (on the left) and Bill (with the filter)
Steve "Snort Rosin" Smith has been keeping me on the side of the angels (and the FCC regs) in the area of harmonic filtering. Today he sent me this Steve and Bill cartoon. Thanks Steve. Just what I needed as I prepare for my next attempt to get my JBOT (with filter!) to behave. Wish me luck!
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
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
Labels:
cartoons
Thursday, November 17, 2011
Amplifier Woes -- Help me! Help me!
When I look in the mirror and I see a haunted, obsessed look in my eyes. My wife senses that there is something wrong in the ham shack. She is right. I have an amplifier that wants to be an oscillator. Help me exorcise these gremlins! Guys, this problem is holding up the production of the next SolderSmoke podcast.
My JBOT amp works fine into a dummy load, but when I connect it to an antenna, it gets unstable. Here are some more details of the symptoms:
I am running the JBOT with a 5 element (two toroids, 3 caps) low pass filter (designed by Doug DeMaw and approved by Steve Smith).
With the antenna connected, all is well UNTIL I raise the power out (by varying the input) beyond about 1 watt. Below one watt, the amp is working fine, and it stable. As soon as I hit the 1 watt point, the amplifier seems to break into oscillation. This does not happen into the dummy load.
The antenna is a simple dipole fed by coax. It shows a low SWR. Even when I put an antenna tuner between the amp and the antenna and bring the SWR down to negligible levels, the instability problem persists.
With the amp disconnected from all other circuitry other than the antenna and the power supply, if I just touch the input capacitor, it breaks into oscillation. This does not happen when the amp is working into the dummy load.
I've bolstered the power supply filtering and decoupling. No luck. I tried some de-Qing of the transformers. No luck.
Any suggestions?
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
My JBOT amp works fine into a dummy load, but when I connect it to an antenna, it gets unstable. Here are some more details of the symptoms:
I am running the JBOT with a 5 element (two toroids, 3 caps) low pass filter (designed by Doug DeMaw and approved by Steve Smith).
With the antenna connected, all is well UNTIL I raise the power out (by varying the input) beyond about 1 watt. Below one watt, the amp is working fine, and it stable. As soon as I hit the 1 watt point, the amplifier seems to break into oscillation. This does not happen into the dummy load.
The antenna is a simple dipole fed by coax. It shows a low SWR. Even when I put an antenna tuner between the amp and the antenna and bring the SWR down to negligible levels, the instability problem persists.
With the amp disconnected from all other circuitry other than the antenna and the power supply, if I just touch the input capacitor, it breaks into oscillation. This does not happen when the amp is working into the dummy load.
I've bolstered the power supply filtering and decoupling. No luck. I tried some de-Qing of the transformers. No luck.
Any suggestions?
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
Labels:
amplifier theory,
Farhan,
India,
JBOT,
troubleshooting
Sunday, November 13, 2011
Backyard Solar Astronomy
Over the weekend I took a break from JBOT amplifiers and did something I've been meaning to do for a long time: solar astronomy. I pulled out my old 4.5 inch Tasco reflector telescope and aimed it at old sol. I know, I know, this can be dangerous, but we were careful -- note that Billy is standing on the other side of the business end of the telescope. In his hands is the paper onto which we projected the solar image. I'd always wondered how I would get the sun into the telescope's field of view without risking my eyesight by using the finder scope. This turned out to be no trouble at all: I just looked at the shadow cast by the tube of the telescope and --using the shadow as my guide -- moved the tube until it was lined up with the sun. We snapped a picture of our results. I think our crude effort compared very favorably with the picture from NASA's Solar Dynamics Observatory. You can see the same sunspots in each image (ours is reversed because we were using a reflector). These images are from 12 November 2011.
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
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
Labels:
astronomy,
propagation,
solar cycle
"The Knack" on a Mysterious Island
Paul, W2IOG, sent a nice e-mail about a very early use of the term "The Knack": 1874 by Jules Verne. (What word did he use in French?). I took a look at the Wikipedia page and discovered that there was indeed quite a bit of "The Knack" on Lincoln Island:
"With the knowledge of the brilliant engineer Smith, the five are able to sustain themselves on the island, producing fire, pottery, bricks, nitroglycerin, iron, a simple electric telegraph, a home on a stony cliffside called "Granite House", and even a seaworthy ship. They also manage to figure out their geographical location."
Hello Bill,
I have been a listener to your Soldersmoke pod-casts for a couple of years now. I am also a regular reader of the blog as well as a long time victim of "The Knack". I was browsing an old book store the other day when I came across a beautifully illustrated copy of Jules Verne's book "The Mysterious Island" copyright 1920. I couldn't resist, and when I reached chapter nine of part one of the book I was really glad I had made the purchase. In the story, which takes place in 1853, castaways on an apparently uninhabited island are trying to make fire for the first time. After trying and failing to make sparks by striking stones together, two of the castaways try the following:
"Pencroft, although he had no confidence in the proceeding, then tried rubbing two pieces of dry wood together, as [primitive people] do. Certainly, the movements which he and Neb gave themselves, if they had been transformed into heat, according to the new theory, would have been enough to heat the boiler of a steamer! It came to nothing. The bits of wood became hot, to be sure, but much less so than the operators themselves.
After working an hour, Pencroft, who was in a complete state of perspiration, threw down the pieces of wood in disgust. 'I can never be made to believe that [primitive people] light their fires in this way, let them say what they will,' he exclaimed. 'I could sooner light my arms by rubbing them against each other!'
The sailor was wrong to despise the proceeding. [Primitive people] often kindle wood by means of rapid rubbing. But every sort of wood does not answer for the purpose, and besides, there is 'the knack,' following the usual expression, and it is probable that Pencroft had not 'the knack.' "
Congratulations on getting that 17 meter rig back on the air!
Paul W2IOG
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
"With the knowledge of the brilliant engineer Smith, the five are able to sustain themselves on the island, producing fire, pottery, bricks, nitroglycerin, iron, a simple electric telegraph, a home on a stony cliffside called "Granite House", and even a seaworthy ship. They also manage to figure out their geographical location."
Hello Bill,
I have been a listener to your Soldersmoke pod-casts for a couple of years now. I am also a regular reader of the blog as well as a long time victim of "The Knack". I was browsing an old book store the other day when I came across a beautifully illustrated copy of Jules Verne's book "The Mysterious Island" copyright 1920. I couldn't resist, and when I reached chapter nine of part one of the book I was really glad I had made the purchase. In the story, which takes place in 1853, castaways on an apparently uninhabited island are trying to make fire for the first time. After trying and failing to make sparks by striking stones together, two of the castaways try the following:
"Pencroft, although he had no confidence in the proceeding, then tried rubbing two pieces of dry wood together, as [primitive people] do. Certainly, the movements which he and Neb gave themselves, if they had been transformed into heat, according to the new theory, would have been enough to heat the boiler of a steamer! It came to nothing. The bits of wood became hot, to be sure, but much less so than the operators themselves.
After working an hour, Pencroft, who was in a complete state of perspiration, threw down the pieces of wood in disgust. 'I can never be made to believe that [primitive people] light their fires in this way, let them say what they will,' he exclaimed. 'I could sooner light my arms by rubbing them against each other!'
The sailor was wrong to despise the proceeding. [Primitive people] often kindle wood by means of rapid rubbing. But every sort of wood does not answer for the purpose, and besides, there is 'the knack,' following the usual expression, and it is probable that Pencroft had not 'the knack.' "
Congratulations on getting that 17 meter rig back on the air!
Paul W2IOG
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
Labels:
books,
France,
Knack Stories
Subscribe to:
Posts (Atom)