Think Before You Measure – Old Test Gear and Why It Is Awesome

old-test-gear-banner

Good, workable test gear is key to enabling our hobby. In this post we will discuss where to procure it at rock-bottom prices, what to look for, how to fix it, and how to tailor your laboratory practices around gear that may not be reliable.

We are lucky to be living in an era with plentiful high-quality test gear. Since the Second World War, surplus test gear has been in abundance at low costs enabling hobbyists, innovators, and academics to experiment and build great things. If you are willing to think before you measure you can save serious amounts of money and have a professional laboratory in your home.

Where to buy
The obvious answer is eBay, but the deals on test equipment are at the hamfests. Don’t be fooled by the name. Hamfests sell much more than amateur radio equipment. Hamfests are swap meets where hobbyists trade electronics of all kinds. Check out the ARRL hamfest calendar to find the next local one near you! I suggest you arrive early, however. The culture of hamfests tends to favor showing up as soon as the doors open and leaving about two hours before the official end. The early bird gets the worm!

[Read more...]

Welcome to the Old School: Restoring Antique Radios

radio-restoration

Before the second world war Radio was a revolution in mass-communication much like the internet today. Fortunes were made and lost, empires built, epic patent battles ensued, all of which resulted in the world being more connected than ever before, which makes for a really great story (and a great Ken Burns documentary).

Last month we showed you how to modify a vintage radio to play your own audio source through it while re-using the existing electronics and maintaining its functionality. In this post we will show you how to restore any vacuum tube radio. You will learn basic repair/restoration procedures from a different era when it was actually worth repairing consumer electronics. Plug into history and get your hands on the most influential technology of the first-half of the 20th century!

[Read more...]

Poor Audio Quality Made Great: Listen to Vintage Music Using an Antique Radio Without Removing the Insides

Sometimes it is not how good but how bad your equipment reproduces sound. In a previous hackaday post the circuitry of a vintage transistor radio was removed so that a blue tooth audio source could be installed and wired to the speaker. By contrast, this post will show how to use the existing circuitry of a vintage radio for playing your own audio sources while at the same time preserving the radio’s functionality. You will be able to play your music through the radio’s own audio signal chain then toggle back to AM mode and listen to the ball game. Make a statement – adapt and use vintage electronics.

Pre-1950’s recordings sound noisy when played on a high-fidelity system, but not when played through a Pre-War console radio. An old Bing Crosby tune sounds like he is broadcasting directly into your living room with a booming AM voice. You do not hear the higher frequency ‘pops’ and ‘hiss’ that would be reproduced by high-fidelity equipment when playing a vintage recording. This is likely due to the fact that the audio frequency signal chain and speaker of an antique radio are not capable of reproducing higher frequencies. Similarly, Sam Cooke sounds great playing out of an earlier transistor radio. These recordings were meant to be played on radios from the era in which they were recorded.

Choosing an Antique Radio

Vintage radios can be found at garage sales, estate sales, hamfests, antique shops, antique radio swap meets, and Ebay. Millions of radios have been manufactured. People often give them away. For this reason, antique radios are relatively inexpensive and the vast majority are not rare or valuable.

Generally speaking, tube radios must be serviced and may not even work. Transistor radios often work to some level. Try to find a radio that is clean and uses a power supply transformer or batteries.

Click past the break to learn how to restore these radios to working condition

[Read more...]

Go Vintage! Learn to Repair and Restore Mechanical Pocket and Wrist Watches.

pw tear down 1

Until recently, watches have been entirely mechanical where each wheel, gear, and mechanism representing a milestone in our understanding of precision manufacturing and timekeeping.

One of the very first watches, created by a locksmith.

One of the very first watches, created by a locksmith.

Today it is nearly impossible to find watchmakers to service or repair vintage mechanical pocket and wristwatches, so we have to do it ourselves. Learn to repair vintage mechanical watches. You can do this and we’ll show you how.

They tick, mechanical watches have a pulse. First created in the 16th century by locksmiths, these early watches could only resolve time down to the hour and for this reason displayed time with only one hour hand.

By the 18th century fusee technology enabled watches to achieve accuracies to within seconds.

[Read more...]

The First Arduino Radar Shield

The first Radar Arduino ShieldThe very first fully operational radar Arduino shield was recently demonstrated at Bay area Maker Faire. It was built by [Daniel] and [David], both undergrads at UC Davis.

Many have talked about doing this, some have even prototyped pieces of it, but these undergrad college students pulled it off. This is the result from Prof. ‘Leo’ Liu’s full-semester senior design course based on the MIT Coffee Can radar short course, which has been going on for 2 years now. Next year this course will have 30 students, showing the world the interest and market-for project based learning.

Check out the high res ranging demo, where a wider band chirp was used to amazing results. Video below.
[Read more...]

Keep those filaments lit, Design your own Vacuum Tube Audio Equipment

Vacuum Tubes Glowing RedIt was a cold January Saturday night in Chicago and we had big plans. Buddy Guy’s Legends bar was packed. We setup directly under one of the PA speakers less than 15′ from the stage. Time to celebrate. Skip the glass, one pitcher each and keep them coming. We’re about to make bootleg recording history. Conversation evolved into bloviation on what our cover art would look like, certainly it would be a photo of our battery powered tube mic pre-amp recently created in my basement lab. We had four hours to kill before Buddy’s appearance. Our rate of Goose Island and Guinness consumption would put us at three-sheets to the wind by 11. Must focus. It’s time, Buddy was on. Much fumbling about and forgetting how to turn on the Japanese-made 24 bit digital recorder with its nested LCD menus, cryptic buttons, and late 90’s firmware. Make it work. We did, just in time for the bouncers to notice the boom mike and battery packs. Wait, wait… maybe we should talk about why tube amps are worth this kind of trouble first.

Yes, vacuum tubes do sound better than transistors (before you hate in the comments check out this scholarly article on the topic). The difficulty is cost; tube gear is very expensive because it uses lots of copper, iron, often point-to-point wired by hand, and requires a heavy metal chassis to support all of these parts. But with this high cost comes good economic justification for building your own gear.

This is one of the last frontiers of do-it-yourself that is actually worth doing.

[Read more...]

Radar Imaging in your Garage: Synthetic Aperture Radar

xband_uwb_fmcw_sar_callouts-no-border

Learn why you were pulled over, quantify the stealthiness of your favorite model aircraft, or see what various household items look like at 10 GHz. In this post we will describe the basics of Synthetic Aperture Radar (SAR) imaging, beginning with a historical perspective, showing the state of the art, and describing what can be done in your garage laboratory. Lets image with microwaves!

[Read more...]

Follow

Get every new post delivered to your Inbox.

Join 96,408 other followers