[Justin] had been trying to find a good tube amp for years, but all the best examples were either expensive or a complete basket case. Instead of buying a vintage stereo tube amp, he decided to build his own using the guts of a Heathkit AA-100, a popular tube amp from the 60s and 70s that doesn’t have a great reputation for sound quality.
This project was based on an earlier project from a decade ago that replicated the very popular Dynaco ST-70 tube amp from parts taken from the Heathkit AA-100. The schematic for this conversion was readily available on the usual tube head message boards, and a few PCBs were available for the input stage.
With the schematic in hand, the next thing for [Justin] to do was get a nice enclosure. High quality tube amps are valued as much for their appearance as they are for their sound quality, and after giving his father-in-law a few sketches, a cherry hardwood chassis stained in a beautiful golden brown appeared on [Justin]’s workbench.
The big iron for this new tube amp was taken directly from the old Heathkit, and a few hours in front of a mill netted [Justin] a chassis panel drilled out for the transformers and tube sockets. The rest of the project was a bit of assembly, point-to-point wiring, and wire management giving [Justin] a fantastic amplifier that will last for another fifty years until someone decides to reuse the transformers.
Transistors have come a long way. Like everything else electronic, they’ve become both better and cheaper. According to a recent IEEE article, a transistor cost about $8 in today’s money back in the 1960’s. Consider the Regency TR-1, the first transistor radio from TI and IDEA. In late 1954, the four-transistor device went on sale for $49.95. That doesn’t sound like much until you realize that in 1954, this was equivalent to about $441 (a new car cost about $1,700 and a copy of life magazine cost 20 cents). Even at that price, they sold about 150,000 radios.
Part of the reason the transistors cost so much was that production costs were high. But another reason is that yields were poor. In some cases, 4 out of 5 of the devices were not usable. The transistors were not that good even when they did work. The first transistors were germanium which has high leakage and worse thermal properties than silicon.
Early transistors were subject to damage from soldering, so it was common to use an alligator clip or a specific heat sink clip to prevent heat from reaching the transistor during construction. Some gear even used sockets which also allowed the quick substitution of devices, just like the tubes they replaced.
When the economics of transistors changed, it made a lot of things practical. For example, a common piece of gear used to be a transistor tester, like the Heathkit IT-121 in the video below. If you pulled an $8 part out of a socket, you’d want to test it before you spent more money on a replacement. Of course, if you had a curve tracer, that was even better because you could measure the device parameters which were probably more subject to change than a modern device.
Of course, germanium to silicon is only one improvement made over the years. The FET is a fundamentally different kind of transistor that has many desirable properties and, of course, integrating hundreds or even thousands of transistors on one integrated circuit revolutionized electronics of all types. Transistors got better. Parameters become less variable and yields increased. Maximum frequency rises and power handling capacity increases. Devices just keep getting better. And cheaper.
A Brief History of Transistors
The path from vacuum tube to the Regency TR-1 was a twisted one. Everyone knew the disadvantages of tubes: fragile, power hungry, and physically large, although smaller and lower-power tubes would start to appear towards the end of their reign. In 1925 a Canadian physicist patented a FET but failed to publicize it. Beyond that, mass production of semiconductor material was unknown at the time. A German inventor patented a similar device in 1934 that didn’t take off, either.
Bell labs researchers worked with germanium and actually understood how to make “point contact” transistors and FETs in 1947. However, Bell’s lawyers found the earlier patents and elected to pursue the conventional transistor patent that would lead to the inventors (John Bardeen, Walter Brattain, and William Shockley) winning the Nobel prize in 1956.
Two Germans working for a Westinghouse subsidiary in Paris independently developed a point contact transistor in 1948. It would be 1954 before silicon transistors became practical. The MOSFET didn’t appear until 1959.
Of course, even these major milestones are subject to incremental improvements. The V channel for MOSFETs, for example, opened the door for FETs to be true power devices, able to switch currents required for motors and other high current devices.
Way back in 2014, Heathkit was a mystery. We knew someone was trying to revive the brand, but that was about it. Adafruit pulled out all the stops to solve this mystery and came up with nothing. The only clue to the existence of Heathkit was a random person who found a geocache in Brooklyn Bridge Park. Since then, Heathkit has released an odd AM radio kit and $150 antenna. These offerings only present more mysteries, but at least [Paul] was finally rewarded for finding the Heathkit geocache. Heathkit sent [Paul] the AM radio kit. He says it’s neat and well documented.
The BeagleBone Black was launched in 2013. The BeagleBone Green – a Seeed joint – showed up last August. The BeagleBone Blue, released just a few months ago, is a collaboration between the UCSD engineering department and TI. Now there’s the BeagleBone Enhanced. Yes, they should have picked another color. Perhaps ecru. The BB Enhanced sports one Gigabyte of RAM, Gigabit Ethernet, two USB ports and two USBs via an expansion header, optional serial NOR Flash for a bootloader, optional six-axis gyro, and optional barometer.
Atmel is changing a few AVRs. There is a new die for the ATMega 44, 88, 168, and the ‘Arduino chip’, the ATMega328. Most of the changes are relatively inconsequential – slightly higher current consumption in power save mode – but one of these changes is going to trip up a lot of people. The Device ID, also known as the source of the avrdude: initialization failed, rc=-1 error, has changed on a lot of chips.
Makeit Labs in Nashua, New Hampshire has a problem. They were awarded $250,000 in tax credits to help them move and renovate. Sounds like a very good problem, right? Not so: they need to sell these tax credits before the end of the month, or they lose them. They’re looking for a few businesses in New Hampshire to buy these tax credits. From [Peter Walsh]: “Under the credit program, a typical business donating $10,000 would save $9,000 on their state and federal taxes! That $10,000 donation would cost them only $1006!” Does that make sense? No, it’s taxes, of course not. If you’re a business in New Hampshire and are looking to reduce your tax burden, this is the solution.
There’s the R2 Builders Club, hundreds of people are building BB-8, but there are a few robots that don’t get enough love from the amateur propsmiths. [Kenneth] just finished up his build of Crow from MST3K. He built Tom Servo a year or so ago and K-9 from Doctor Who. The beautiful thing about building MST3K robots and Doctor Who props is that you’re probably working with a larger budget than the prop department had.
On today’s issue of, ‘should not be attempted by anyone, ever, under any circumstance’ here’s how to build a table saw at home. Yes, it’s a table saw built from a piece of aluminum, styrofoam, hot glue, and a shoe box. The guy really botched it by not going for the zero clearance insert here, but at least the fence is only a few dozen degrees off parallel with the blade.
March 18th through March 20th is the Midwest RepRap Festival in Goshen, Indiana. This is, by far, the best conference, meetup, or festival we go to year after year. We’ll have a few members of the Hackaday crew at the event, and rumor has it the Internet has made it to Indiana this year.
Adafruit got a writeup in the New Yorker. The article is technically about the art of PCB design, but as with most general interest pieces on electronics it is awash in non sequiturs and simply defining the terminology.
[Oscar] built a miniature replica of a blinkenlight computer last year for the Hackaday Prize. This was the PiDP-8/I. While it looks awesome, the PDP-8/I is inherently limited. [Oscar] has his design methodology down, and now he’s working on a miniature replica of the king of the PDPs. It’s the PiDP-11/27. It’s just a prototype and render now, but the finished project will have custom switches, a handsome bezel, and will be much more capable.
MAME is now FOSS. That’s great news, but think about the amount of work that went into making this happen. MAME is 19 years old, and that means everyone who has contributed to the project over the years needed to sign off on this initiative.
About the most charitable thing you can say about their “Pipetenna” is that it’ll probably work really well. Heathkit throws some impedance and SWR charts on the website, and the numbers look pretty good. Although Heathkit doesn’t divulge the design within the “waterproof – yes, waterproof!” housing, at 6 dBi gain and only five feet long, we’re going to guess this is basically a Slim Jim antenna stuffed in a housing made of Schedule 40 PVC tubing. About the only “high-end” component we can see is the N-type coax connector, but that just means most hams will need and adapter for their more standard PL-259 terminated coax.
Regardless of design, it’s hard to imagine how Heathkit could stuff enough technology into this antenna to justify the $149 price. Hams have been building antennas like these forever from bits and pieces of wire lying around. Even if you bought all new components, including the PVC pipe and fittings, you’d be hard pressed to put $50 into a homebrew version that’ll likely perform just as well.
The icing on this questionable cake, though, is the sales copy on the web page. The “wall of text” formatting, the overuse of superlatives, and the cutesy asides and quips remind us of the old DAK Industries ads that hawked cheap import electronics as the latest and greatest must-have device. There’s just something unseemly going on here, and it doesn’t befit a brand with the reputation of Heathkit.
Heathkit, the storied purveyor of high-quality DIY electronics kits that inspired a generation of enthusiasts and launched the careers of many engineers, has returned from the dead. We think. At least it seems that way from this build log by [Spritle], an early adopter of the rebooted company’s first offering. But if [Spritle]’s experience is any indication, Heathkit has a long way to go to recreating its glory days. Continue reading “Heathkit’s Triumphant Return?”→
There is no company that has earned more goodwill from electronic tinkering hobbyists than Heathkit. For more than fifty years, Heathkit has been the measure all other electronic kit manufacturers have been compared to. Kits for everything – from televisions to radios to computer terminals – were all sold by Heathkit, and even now, nearly a quarter century since the last kit left the warehouse, there is still a desire for this manufacturer to rise like a phoenix from the ashes. Heathkit lives once more, and this time it might be for real.
In recent years, Heathkit has had a confusing, if not troubled business plan. The company started manufacturing its signature products – electronic kits of every kind – in 1947. Production of these kits ended in 1992, and the company went on for another few years manufacturing educational materials and lighting controls. In 2011, Heathkit said they were back in the kit business, before shutting down a year later.
This morning, the president of Heathkit sent a message to the ‘Heathkit Insiders’ email group explaining the goings on and new happenings:
We’ve designed and developed a wide range of entirely new kit products. We authored the manuals for these kits, complete with the beautiful line art you rely on, preserving and respecting our iconic historic Heathkit style. We developed many new inventions and filed patents on them. We relocated Heathkit, and set up a factory, and a warehouse, and offices, in Santa Cruz, California, near Silicon Valley. We built the back office infrastructure, vendor and supply chain relationships, systems, procedures, operations methods, and well-thought-out corporate structure that a manufacturing company needs to support its customers, to allow us to scale instantly the day we resume major kit sales. All this effort enables us to introduce a fleet of new kits and helps ensure Heathkit can grow, prosper, and continue to bring you great new products for a very long time.
The new Heathkit shop features their newest product, the Explorer Jr. AM Radio Receiver kit, a small kit radio available for $150. It’s actually a rather interesting kit with a nice design and an air variable cap for tuning, just like radios from a century ago. Whether anyone will pay $150 for an AM receiver in this century is another question entirely. The 21st century rebirth of Heathkit doesn’t just mean kits; they’re making apps now, with the first release being a crystal design tool for Android.
Virtually everyone in this little corner of the Internet, from Adafruit to Sparkfun, to Make magazine to everyone with a 3D printer owes a debt to Heathkit. This is the company that first turned DIY electronics into a successful business. Heathkit was the first, and they deserve to be recognized as the pioneers of the field.
The Donner Party were pioneers, too; just because you’re breaking new ground doesn’t mean you’re successful. The Heathkit of the 90s shuttered its doors for a reason. The factors behind the 1992 closing – cheap stuff from China, and the fact that not many people want to build their own electronics – are still with us. Still, the market for DIY electronics may be big enough, and Heathkit’s back catalog may be diverse enough that I won’t have to write another ‘Heathkit dies yet again’ post in a year or so. We can only hope.