- 2022
- Apr
- 14
1959 Blonder-Tongue Audio Baton (B9) Graphic EQ Rebuild
(See my later post for the Sams folder / schematics for the BT B9.)
A long time ago when eBay was still fairly new, a set of heavily modified Blonder-Tongue Audio Batons showed up for a cheap price. These are the first commercially available graphic equalizer, featuring 9 bands. Tube complement for this device is 5 12AX7 used as amplifiers in the EQ stages, and 1 6X4 rectifier to provide power for the unit. 3 lamps to backlight the adjustments ran off the AC filament transformer.
I’m not sure what was going on with these units, but two of the potentiometer holes were punched out on one of the chassis, and two extra tubes had been installed. Multiple modifications had been made to the electronics, which were in somewhat of a state of decay. Old carbon comp resistors had drifted, capacitors had become leaky, and all of the mods just made a mess of the unit. The other unit didn’t have mods, but the electronics were in the same state of decay.
The first thing I did was remove all the components except for sockets, transformer, and terminal strips. New components were purchased, including orange drops and mylar film capacitors, carbon film resistors, and of course, new wire. Holed punched in the chassis were re-filled with washers of the correct size. Potentiometers were saved where possible and cleaned. The chassis were re-wired and all of the new components were placed. I decided to do my own layout and wound up with a more compact layout than the OEM layout.
The original case, of which I had one, used weird bi-pin lamps to backlight plastic tubes with a candy-cane stripe on it. The stripe appeared in a slot cut in the face, and as you turned the pot the stripe “moved” up the slot. This was re-assembled and, unfortunately since the face had been damaged, I used stick-on labels to identify the bands. The odd number sticker was left on the face. I assume this is from a previous auction.
The second chassis was more of a challenge. Since I didn’t have a case, I settled on a rack chassis from SES-COM, a company that used to manufacture such items but has since transitioned to audio products. More space allowed for some added some amenities such as VU meters using a precision rectifier circuit and a push-on/off control circuit for both units. I replaced tubes as needed, using NOS RCA and other brands as available in my personal stock. A final check, and they worked - probably just as good or better than new.
I was never able to determine what the mods were, save that I’ve seen others reference strange mods where the chassis was punched out and extra tubes added.
In the end, there was more fun had rebuilding these units as opposed to using them. They’re simply graphic EQs that consume a lot of power and have the added noise of a tube circuit. A modern unit works just as well, and has more bands. I ended up relisting them on eBay around 1998 (I think?) and selling them to a studio. That’s something I kind of regret, but as I said - in the end it’s just an old version of a new circuit.
Unfortunately, since this build pre-dated digital cameras, all I have left are these photographs taken with a friend’s Samsung point-n-shoot. They’re not the best, but here they are.
- 2022
- Apr
- 3
The “gotchas” of cheap technology.
This was originally published on my Blogger page of the same name.
Some time ago, I had the idea that I’d like to develop something with the popular and inexpensive ESP line of microcontrollers. These offered a mature WiFi stack, a relatively large amount of program space, and were available in many easy to use packages that include a very cost-effective pin header version.
One of the things that I didn’t do during the development stage is pull the FCC paperwork for the device. Device is kind of a misnomer here, since there are multiple devices and only the chipset in a particular configuration seems to be certified. Had I done that, this probably would have been avoided.
I had designed and deployed a number of different boards to do temperature and humidity testing around the house. When I started to have issues with other systems, there were probably about 10 units operating in various capacities. However…
The original production run Wetbird device.
Version 2.2, cleaned up a little.
A Hotbird temp device and an OWL expansion board.
A Hotbird using an unobtanium ESP-002.
My first clue that something was amiss was the fact that my garage door opener had started acting up. It being several years old, I blamed age and potentially some new radio equipment installed at a nearby airport. This device operates at 320MHz… The next clue was that my old RF X10 control system had quit responding to the controller, and refused to operate no matter what module or receiver I tried. Since I had NOS devices available, and they didn’t work, I figured there was something amiss here. The X10 devices operate on 310MHz in the USA…
So what had changed? On investigation, I noticed that the signal indicator on the garage door opener was solid on, indicating it was receiving something. I still wasn’t sure what was going on, but I ran into another issue. The humidity sensor I used on the boards, a cheap device commonly available in the hobby market, had started failing. They would quit responding (sometimes!) and come back with a power cycle. I took them offline to try and troubleshoot the problem, and every other system started working again.
On a hunch, I grabbed my cheap SDR stick and set it up to look at the spectrum from about 305-325MHz. And right there it was, a big spur at 319.98MHz. Close enough to the opener’s frequency to kill it, and wideband enough to interfere with the X10 system’s unfiltered receiver. I took the few remaining devices offline and everything went back to normal.
It turns out that there are a number of spurs emitted by the ESP chipset. One of those, the important one for my testing, was right around 319.98MHz. You can view that particular document here: https://fccid.io/2ANHN-ESP8266 but note the device tested doesn’t look anything like the ones available for consumption.
This is a crying shame, because the ESP chipset shows up in many places and is so cheap and easy to use. The next available alternative is the Arduino WiFi devices, but those are fairly expensive at $50ish, and still have certain issues that have been poking around for years.
For now, I’ve shelved that project but have thought about reviving it. The new RP2040 chipset is available with a wired interface for about $10, and while it won’t be as easily deployed as a wireless device, the wired connection insures it won’t have any spurs knocking my garage door opener off the air.
- 2022
- Mar
- 26
Updating the Linksys WML11B media player for the modern age
It’s interesting to note that consumer grade Ethernet has been with us, in a standard comes-with-everycomputer way for about 25 years. This means there’s a wealth of Ethernet-enabled devices out there that may not be good for the professional or other use they were originally intended, but are fine for the home lab hobbyist. One of those items is the Baytech RPC-3 Ethernet connected power switch. A fully obsolete device with only a telnet server, it’s perfect for home use.
A device that came out of the early days of Web 1.0 is the Linksys WML11B Wireless-B/Ethernet enabled Internet Music Player - think those streams you played in Winamp back in the day. Officially streamed by the Shoutcast server package, there are now open source replacements (Icecast) that do the same thing. A small machine like a Raspberry Pi and some music means you can stream your own stuff, if you’re so inclined. (Keep this to yourself, the music industry giants are unfriendly towards anyone they think may be depriving them of a dime.)
While it’s common now to lock a device to a single service so the device dies with the service, this wasn’t really the case back then. The WML11B did have a music directory service provided by Linksys, and later by a third party - those are long gone. What makes this device of interest is it will still connect and play Shoutcast/Icecast streams without issue.
There are a couple of caveats, however. You need to update the firmware to the last package available, the one provided by the third party music service. However, even though this service doesn’t exist, the firmware is simply a modification of the last Linksys firmware and makes the device available on a local network. That firmware package and the updater can be downloaded from this dropbox link:
Firmware https://www.dropbox. … mls11b_files.7z?dl=0
The other caveat is that it works on Windows XP, and nothing higher. I tried Windows 7 with no luck. 8, 10, and 11 are right out. So you’ll need to find a friend with an old XP machine, or dig one up for yourself. Inside the file (You’ll need the 7zip archiver to open it) are a number of files. Start with the ones marked FAQ and you should have a good handle on where to start.
The rest of the files are various firmware versions, data and documents on the device, and other things of interest. This all came from the Yahoo! groups forum, now gone sadly. If you’d like to read those messages, you can download them here:
Message archive https://www.dropbox. … s11bmsg.tar.bz2?dl=0
This is a direct raw dump from the Yahoo! group, and is in .tar.bz2 format. 7zip should have no trouble with this.
It’s kind of a pain to get it updated, but once you do you’ll find an interface similar to other Linksys products. If you’ve messed around in a router you shouldn’t have any problem with this.
(I think it goes without saying, don’t open a 802.11b wireless network. Connect this thing with Ethernet.)
- 2022
- Mar
- 23
Just because it fits doesn’t mean it will work…
One of the things you have to deal with while using old equipment is ancient batteries.
This 1985 Kaypro 2X+88 machine has an early real-time clock, but hasn’t kept time for the better part of two decades.
Interestingly, the battery (the yellow cylinder in the right of the picture) was still available as an off-brand replacement. Voltage checked ok, but soldering the battery on the board resulted in a no-boot condition. The battery was removed and the board completely cleaned of any flux before re-installation and successful boot.
I’m not sure what happened here, but that’s another danger of old equipment - stuff may just not work anymore. I assume that either the little bit of flux on the board was causing issue, or perhaps the clock chip is now damaged from the long-term low voltage. In either event, I need to see if I can get a NOS clock chip before replacing the battery with an off-board 3V pack made up of standard alkalines.
The machine seems happy, and has been sitting at directory for quite some time.
This post is from my LinkedIn profile, you can view it here:
- 2022
- Mar
- 23
Don’t overlook the power cord.
One of my pieces of bench equipment needed some minor maintenance recently.
This Eico 147A Signal Tracer, used for tracking audio down in equipment as well as pulling a demodulated signal off AM circuits, needed a new line cord. There really wasn’t a lot to do here save to be careful when working around older components.
The device itself is very clean inside, and appears to have seen very little actual use before my acquisition. As you can see by the picture of the cord itself, it was well past time for replacement.
This post is from my LinkedIn profile, view it here:
- 2021
- Jul
- 20
Getting set up.
Welcome to Projects from the bottom drawer and wereboar.com. This blog used to be hosted on pygg.xyz, and was hosted on blogger.com before that. Pygg has since been relegated to a (poorly performing) redirect to here, and the blogger links are long gone.
If you’ve arrived at this page by scrolling through my blog, thank you. This is currently both the beginning and end, check back soon for more posts about hamfests, projects, and the random ramble about tech things.
If there’s something you’d like to see more of (or less!) then LinkedIn is a good way to contact me. If you’d like a more user-friendly venue, you can find me on Mastodon. That avenue is fairly new to me, it will generally follow new posts as they appear here, with comments and conversation.
I also post infrequently on satellite.earth, a nostr instance. This is a federated, decentralized social network that doesn’t limit what you can see. Anyone can post in this forum (with signup,) check it out if you’re interested.
Again, welcome, and thanks for stopping by. See you at the hamfest!