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Ask Fran:
Introduction to the Commodore 64 (C-64) Computer
Ask
Fran: Build Your Own Microscope!
Fran's
Favorite Toy In History: Mr. Wizard's Experiments In Electronics, 1972
Soviet Vacuum
Fluorescent Display Project
Nixie Counter
Project
You can
make a radio!
The
Frantone Fretboard
New Grommet
Press Project
Repair and
Maintenance of the IBM Selectric II Typewriter
The Saturn
V IU Computer
Of
Human Design
What
Ever Happened to Fortran?
The Vacuum
Tube Burner Machine Projects
Vacuum
Tube Tester Machine Project
The 'Model
A' Stereo Tube HiFi
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(Nov. 2012) |
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(Nov. 2012) |
Fran's
Favorite Toy In History:
(Oct. 2012)
Mr. Wizard's
Experiments In Electronics
c.1972
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(Feb. 2011) I recently completed my second kick press project. I bought a vintage table and mounted my hand press to it, then constructed the foot pedal with the necessary leverage to amplify the force of the hand press from 10:1 to 18:1. This new kick press delivers 650lbs of force to the die with just 36lbs of pressure on the pedal, and all completely hands free.
I then wanted to make this kick press more than just a grommet press, so I designed a series of practical die sets for other press operations that I do frequently. I contacted my good friend Bud Mohrman at TAPE Inc. to make the dies for me, and fortunately he is one of the last hard core machinists that can cut dies directly from high strength tool steel. I made some initial sketches
from my mental images to better visualize the manufacturing tolerances
for these dies.....
I then made a series of mechanical drawings that contained my calculations for tolerance and proper contouring, finish, and measurements for each die. Mechanical drafting is a specific language which communicates the design concept in a way that another person can manufacture the part to exact proportions and have the parts interact with proper tolerances. The Machinist will not make judgment calls, it is up to the designer to be very clear on all parameters. If the designer makes a mistake or miscalculation then the part will either not fit, or not function as needed. These drawings were made with a requested manufacturing tolerance of ±.005 inches. No computers here, I do everything in pencil on paper at my drafting table....
The results were very good, and Bud did a magnificent job. There were a few small tweaks, and the dies work great, as expected. Here are the actual dies....
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(Nov. 2010) Like most of my generation, BASIC was the first high level programming language that I was exposed to. My first experiences with a computer were on the Tandy TRS-80 back in 1979. I then got pretty good with Commodore BASIC on the C-64 in the early 80’s, and then with the somewhat more advanced Apple II-e in 1983. The Commodore could be unstable, and it often conked out from overheating in the summer, obliterating possibly hours of keystrokes. So if you knew what was good for you a constant back up to tape was part of the lifestyle (cassette was standard). Despite that, the C-64 still had a lot more in the way of fun than the Apple because of its Sprites and the SID analog synthesizer chip that 8-bit fanciers still love to sample to this day. The C-64 allowed for some sharp honing of a programmer’s code crunching chops too. Due to its line structures and icon based short key codes you could pack in some pretty efficient code (and you really had to) with up to 80 characters per code line, and the control ports with ‘peek’ and ‘poke’ commands allowed the C-64 to control and monitor any peripheral TTL or CMOS device you might want to design also, and that was pretty powerfully cool for an electronics designer’s shop in 1984. True, if I would have had the means I would have gotten the Heathkit computer system kit with the home robot in 1982 and built it all myself, but I digress. When I got to college in 1985 they were still using an IBM mainframe that ran Fortran 77 and COBOL. The punch card readers were still plugged in, but fortunately I entered in the terminal era. Most geeks know about COBOL’s threat and Y2K, but why Fortran faded away is harder to judge. Fortran was short for Formula Translating, and it was one of the first high level programming languages developed by IBM in the 1950’s. It was a very popular workhorse for processing numerical data for decades. I do hear that there are hangers on that still update and use modern versions of the old Fortran, and a brief search showed that despite the prevalence of many other languages that Fortran is still used for supercomputing and number crunching applications today. It makes an old dinosaur like myself feel just a little younger knowing that good old formula translating is still going strong, silently, cranking inside a mainframe somewhere.
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Vacuum Tube Tester Machine Project (July 2006) Now the story can be told....
Below is a detail of the
docking port for the tray. Note the hand machined cool lever handles
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I originally began the Model A project in late 1999 in preparation for the 2000 New York Noise HiFi builders show. It is an original all tube design, with tube rectifiers, regulators, indicators, and amplifiers in a dual parallel configuration and single toroid power transformer. It has twin 300B triode fixed bias finals and a tube bias supply with dual 6SN7 drivers in a classic configuration. Output is 7 watts per cannel. The dual 6HU6 CRT peak level indicators are out in front which are powered by their own tube regulated 210VDC supply. The chassis and all physical components are entirely hand made from raw stock aluminum by myself. I built the amp over a three month period on my kitchen table in Greenpoint, Brooklyn. I even hand made the single stereo attenuator using a dual gang 48 position continuous coin silver rotary make-before-break switch with 96 wire-wound precision resistors in a logarithmic curve. All of the power supply components are in the top of the chassis and all of the audio components are in the bottom. The two output transformers are set one in each side pedestal and there is forced air cooling throughout. The 'Model A' also runs through a set of high efficiency crossover MTM style speakers that I constructed later in the fall of 2000. It sounds like the voice of God, if there was a God and they had a voice. It is also very, very heavy. I never entered it in the
show, but that is a different story.
Constructing the chassis of the Model A, January 2000. On the left the output transformer is visible as the main components are being installed. Note the stove - Yes, I really did build it on my kitchen table! When you live in Brooklyn space is relative.
The finished chassis and
stereo attenuator.
Another video of the Model
A in action, also showing the real time bias meter. The bias meter
is made of stacked comparators and calibrated to a fixed internal reference
voltage, and it measures the current output of each 300B output tube by
sensing the voltage drop across a 50ohm power resistor on each cathode,
which you can see on the schematic as the T1 and T2 points. The scale
of the meter is set so that the lowest green indicates 65ma, the yellow
80ma, and red is over the top.
The schematics for the Model
A amp design and power supplies:
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In my shop,
The Frantone Factory
Williamsburg, Brooklyn
2003
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from an article about me and my Hep Cat design in 1996 - |
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The Mysterons, 1996 (Jezebel, Frantone, The Evil Dr. Z) |
The Mysterons, 1997 |
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