July is always a pretty busy month – it’s finally summer in the Pacific Northwest and so my attention is divided between my electronics work and spending time in the great outdoors. I have a few things in the pipeline for the month of July which I hope to accomplish.
First, a client has brought me their Grundig 5399U/S radio from 1965 for repair. It has some severe mechanical issues and is currently holding for parts, but it will be featured in a repair article later if they come through.
I’ll also be fixing this Bose 901 Series 1 Active Equalizer, brought to me by a friend whose vintage hi-fi speakers started to experience distortion. It turns out modern capacitors can fail too!
Finally, I hope to fix up my early ~1931 General Electric J-105 antique radio. It’s in beautiful cosmetic shape looking like it just rolled off the showroom floor, but the electrics are predictably dead after 81 years and will need reconditioning.
February was a pretty slow month for projects, about the only one I managed to accomplish was fixing the Firestone car radio. March should be a bit more productive, though. I have a list of a few projects I’m planning to try and complete.
First up, a pair of Grunow radios that are vastly similar to the pair of 589s that I’ve fixed in the past – a Grunow 566 and a Grunow 588. The 588 even has a Teledial.
I’ll probably also start working on a a Jewel radio that was a Christmas gift:
I also have a kit amplifier left mid-project, I’ve mounted the iron and hardware but none of the connections or components yet. (It’s a stereo amplifier with a 6SN7 dual triode driving a pair of 6V6 in push-pull for each channel, and should sound pretty good when complete.)
Plus other projects that seem interesting along the way. Stay tuned!
I tend to stay away from political commentary on my blog, but this is too important not to talk about. The PROTECT IP act currently the subject of hearings in Washington, D.C. is set up for a fast-track to pass. Testimony from the technology industry is being prohibited in the committee, so technologists and infrastructure companies aren’t being allowed to have any say in the bill that will effectively set up the “Great Firewall of America” and allow Hollywood to become the ultimate arbiters of what content isn’t allowed to be posted online, backed up by the Department of Homeland Security. Unless the possibility of spending five years in Federal prison because you posted a video of yourself singing a cover of a pop song to YouTube is something you enjoy, it’s time to take action.
Send this form letter, or write your Congressman a personal message. Don’t let the Government, in partnership with the entertainment industry, execute a power grab possibly exceeded only by the PATRIOT act.
I generally write about radios and older projects here, but I do in fact work on a lot of other projects as well. This one is pretty interesting, a new and intriguing product that stands a very solid chance at becoming a very interesting force in low-end computing is on the verge of making it to market: the Raspberry Pi. It’s a pretty simple concept: a $25 single-board computer with an ARM chip about as powerful as a mid-level cell phone, some RAM, and a few interfaces. Not a very powerful device, but it’s designed to facilitate teaching computer science in schools.
It doesn’t look like much, but it has a network port, HDMI and TV outputs, two USB ports, audio, and a variety of serial GPIO ports. The educational uses of it aren’t very interesting to me…but the possibility of a reasonably capable computer that can be programmed in high-level languages and used to create complex applications on the cheap is incredibly exciting. I’m interested in using these to develop a variety of “appliance” type network applications, passive single-purpose complex devices that could be produced for under $100-200/set including all the other parts.
Connectivity appliances? Home security and automation terminals? New communications devices? Weatherproof terminals to web browse in the shower? The possibilities are endless – this tiny device needing only 3.5W of power to run, it can happily run from a cell phone charger or even a battery.
I’ll be the first in line to pick up a pair of these. Granted, I’m not at all excited about the fact it runs Linux as that means I’ll have to learn a new platform and environment to accomplish much, but I think it might actually be worth it to do so.
If you had a tiny fanless networkable PC, what kind of homebrew projects would you want to see?
Recapping the projects I completed in the month of October. I started out with a few goals:
- GE LF-116 Radio Repair
- Sanyo Solid-State Receiver Repair
- EICO 460 Oscilloscope Overhaul and Tune-Up
I’ve had this idea for quite a few years but haven’t put much time into it, between everything else I’ve been going on. Once or twice a year for the past five or so years, I’ve posted on Craigslist seeking a broken cello to turn into an art project. Finally, the ad hit and I think I can make it happen.
Verve//Remixed 3 has an incredible album cover. You should buy their music for that reason alone.
I’m hoping to make my own version of the Cello Boombox on the cover…and this will be my starting point, a cello with a broken neck the owner wasn’t interested in repairing. The neck snapped off, the bridge is missing, and there are quite a few cracks (although they aren’t visible unless you look closely) and it needs to be re-glued.
I doubt I’ll do anything with this until next year at least, but now it’s a possibility. I’m just glad I was able to find a broken cello, I wasn’t willing to destroy a functional instrument for this. Not to mention, a working cello costs a lot of money.
There are a few things to consider:
Speaker size and placement. How many drivers will I use, and what types?
Cabinet volume and phase cancelling. If I configure this as a stereo boombox, I’d need to isolate the enclosures internally from each other or the out-of-phase parts of the left and right channels of the audio could cancel or introduce distortion.
Audio source. The Verve Remixed album cover is concept art, not a real product, so the knobs and panel meters and a floppy disk drive aren’t things I could realistically include. Do I mount a small music player in the center – maybe an iPod Touch, or a small Android tablet? Or should I just make this into an artistic speaker without its own audio source?
Power. If this is going to have its own amplifier, how am I going to power it? An outboard power pack? Rechargeable batteries inside?
If anyone has suggestions on those design topics, I’d love to hear them, or from anyone else who has attempted a project like this.
In addition to writing once in a while, I read a lot of blogs. They’re about a quarter political, a good bunch of news, about a quarter are photo feeds, and the rest are life interest and hobbies.
One of the more interesting ones is “Art of Manliness” which runs all manner of short and frequently humorous how-tos on topics like shaving with a straight razor, catching a horse, fixing things on your car, you get the picture. They recently put up a great article about re-purposing a broken antique radio into an external speaker for an MP3 player.
When I encounter a broken antique radio, my first instinct is to fix it up and add an input for the iPod but sometimes they’re just too far gone to save or aren’t valuable enough to spend a dozen or more hours repairing. In that case, tapping into the radio’s volume control and re-using its existing speaker is a good alternative and is usually a reversible modification. A lot of purists might complain about ruining an antique to make this repair, but it’s a reversible modification and let’s face it – fixing the radio up well enough to receive a signal and then using an AM transmitter isn’t going to sound nearly as good most of the time, anyway.
Around WW2, they changed how antique radio speakers work. Before then, speakers were electrodynamic using a field coil instead of a magnet. Since they have no magnetic field if they’re not fully powered by a very high voltage, they won’t play sound – you need a permanent magnet speaker. I mentioned this to the author and he updated the copy of the page to reflect this important information that might have resulted in a lot of disappointment for someone who used the wrong type without knowing:
Important Note: Commenter J.W. Koebel brought to our attention that if you want to use the radio’s original speaker like we do in this project , the speaker needs to be a permanent magnet speaker. Radios from about the mid-1940s and on should have permanent magnet speakers. Earlier radios used electrodynamic speakers. Our amp won’t work with electrodynamic speakers.
How do you know if your old-time radio has permanent magnet speakers? Check the back of the speaker. If it has 2 or 3 wires going to the speaker, it’s a permanent magnet speaker.
Better-known gadget blog Lifehacker picked up the story, and devoted about 1/4 of their summary article’s copy to that same warning.
Two caveats: Make sure your vintage radio is not terribly valuable before you take it apart and also make sure the speaker in the old radio is a permanent magnetic speaker and not an earlier electrodynamic speaker that won’t work with the new amp. If 2 or 3 wires are connected to the speaker, it’s a permanent magnetic speaker.
That’s pretty cool. I didn’t think much of it at the time, but I’m glad some of my advice will help fellow hobbyists have a successful project. (Also, this is my blog’s 100th post!)
A recent random assortment of ideas:
It’s easy to get media content from a computer to a television, but it’s difficult to get any kind of external media back into a computer. I have a fairly involved computer setup at home. My workstation is connected to two 20″ monitors and a 46″ LCD. A friend was in town for the weekend, and we were looking for an easy way to make a YouTube video play from his laptop onto my monitor, without actually taking away my control of it. I have two sets of input devices, one at my desk and one near the couch, to control the computer when it’s being used for media. We ended up just switching off who had control of the single mouse cursor between the two input devices. The ideal solution? Either multiple mouser pointers, assigned to the unique input combinations – or a VGA capture interface to make another computer’s input appear in a window. VGA capture devices exist but are absurdly expensive, and there’s no multi-pointer support in the operating system. Most laptops these days have dropped an analog TV output in favor of HDMI or DisplayPort outputs meaning they can’t be connected to an inexpensive TV-capture card.
At about the six month mark, as expected, my phone has started acting up. This has been the case with most every smartphone I’ve owned – a Nokia running S60, an HTC 8525 running Windows Mobile 6.5, a G1, and now my G2 running Android. Reliably at about the six month mark they’ve all started acting up in ways that make me suspect the hardware is failing: lockups and reboots, screen glitches, data disappearing off the memory card randomly and visible dust between the LCD and the glass so deep in the phone the only way I can see it getting in is via osmosis. Hard reset doesn’t fix the problem. Have even high-end smartphones become disposable commodities?
Hallicrafters 8R40 Upgrade: On the back of my bench I have a Hallicrafters 8R40 radio receiver from 1953. It will be a good performing radio when I’m through fixing it up, and I’ll be using it to try and pick up long distance contacts. One thing about far away faint signals is that they can be tough to hear even with the audio turned all the way up, the 8R40 only has a single-ended 6V6 output that maxes out around 4.5W of audio power into a not-that-efficient speaker. From Parts-Express, I bought a few Dayton Audio DTA-2 Class T amplifier modules, based on a Tripath TA-2024 chip. They’ll pump out about 20W of power. I’m planning to use one of these modules inside the back of the Hallicrafters to allow it to drive an external speaker at 20W in a reversible modification. I expect I’ll split the detector’s output and use the module amplifier for the external speaker only; leaving the build-in speaker powered by the tube.