Archive for the ‘Misc Stuff’ Category

Reason for Lack of Posts this Month

Wednesday, April 1st, 2015

I’ve been busy working on my VCF east exhibit.

It’s about the relationship between HAM radio and early personal computers. I have lots of interesting things to blog about. However I want to unveil my discoveries and experiments at VCF east, rather than reveal the exhibit contents ahead of time through blog posts.

Come to VCF east next month, and you’ll get the first look at what I’ve been busy working on. Sometime during or after VCF east, I plan on putting up some web pages and will have quite a backlog of stuff to blog about.

Familiar Sight

Friday, March 6th, 2015

B-32 Bombers under construction at Air Force Plant #4

B-32 Bombers under construction at Air Force Plant #4

I was killing some time the other day, browsing the web, finding out about the great warplanes of World War II, when I ran across this photo.

The photo was found on this blog page which contains much information about it: http://rarehistoricalphotos.com/b-32-bomber-factory-fort-worth-texas1944/

After looking at it, and reading the caption, I wondered if this was the same war plane factory that I had visited in the mid 80’s. At the time, I worked for the Computer Systems Division of Gould, Inc. This company produced super-mini computers and sold a large percentage of the computers used to power commercial and military flight simulators. When introducing a new version of the computer, some of the engineering team attended a show in Fort Worth, Texas. Before the show, a local sales representative invited us to visit the General Dynamics factory outside town. At the time, General Dynamics made F-16 fighter planes at the plant. We got to walk out on the factory floor. We could see workmen constructing F-16s, one rivet at a time. No automation or moving assembly line there, those planes were practically hand-crafted. Our guide told us that it was the longest factory in the world. He said that they rolled raw material in one end and complete airplanes out the other end. It was a very cool experience. Later on, at the show, I got to “fly” a General Dynamics F-16 cockpit proceedures trainer. What a memorable trip that was.

Follow this link to see F-16s under construction in this factory.

Well it turns out that this factory was indeed the same factory as produced 3000 B-24s during World War II and over a hundred B-32s towards the end of the war. It’s official name was Air Force Factory #4. There are a number of photos of this place while B-24s Liberators were being constructed on the Library of Congress website.

B-24s Under Construction

B-24s Under Construction

http://www.loc.gov/pictures/item/oem2002005697/PP/

Today the F-35 lighting II is produced at the facility.

Infant Mortality?

Thursday, February 26th, 2015

If a 40 year old, NOS, IC dies after a few hours usage, should it be considered infant mortality?

glossory:

  • IC – integrated circuit
  • infant mortality – a term used to describe an electronic product that has a terminal failure soon after being put into use
  • NOS – new, old stock – an old part that hasn’t been used and is essentially is new condition, except for shop wear
  • shop wear – physical wear that can occur to an item that is on the shelf in a store or in storage in a warehouse
  • terminal failure – a failure that precludes using the item for it’s intended purpose
  • Corey,
    Thanks for the inspiration for this post – too bad you were bitten.

    ExTech EX-330 multimeter snapshot review

    Tuesday, January 6th, 2015

    Cutting to the chase, I’m a bit disappointed with this multimeter. I bought it primarily based on low price, features and relatively good review in Dave Jone’s EEVblog #91.

    The Ohm, DC volts and Diode check function work as expected. Some of the other features don’t work as well as I had hoped.

  • AC volts doesn’t work in millivolt range
  • Capacitance tester is basically unusable, except for a very small range of smallish caps
  • My sub $100 Tek 465 oscilloscope can be used for checking AC volts, though accuracy is approximate.

    The Fluke counter I picked off of eBay and repaired for around $40 is vastly more accurate and usable for frequency readings.

    At some point, I’m going to have to pick up a more capable capacitance tester, but in the past I have hacked one together out of spare parts on the few occasions when I really had to have one.

    For the features that do work well, the ergonomics of the EX330 are quite nice, much better than the $29 unit that it’s replacing.

    Bottom line – you get what you pay for, though I’m starting to believe that if it works or can be repaired, there can be some real bargains found in the vintage test gear marketplace. :-)

    Opinion – how not to take out Isis

    Wednesday, September 24th, 2014

    Trying to take out Isis by bombing them from a few high flying aircraft is like trying to destroy a fire ant colony by stomping on it’s nest.

    This approach has only really succeeded once – and that was when we resorted to using nuclear weapons at the end of World War II.

    There is an old saying that might lead to an alternative approach that might have more promise – Keep your friends close and your enemies closer.

    New Toy

    Monday, September 1st, 2014
    HAL ST-6

    HAL ST-6

    This is the first piece of gear to be used to expand my vintage computer hobby into a new direction.

    Dover Mini-Maker Faire Experience

    Monday, August 25th, 2014

    Dover, NH Mini Maker Faire

    Dover, NH Mini Maker Faire


    Just sharing some experience from the Dover Mini Maker Faire which was Saturday. I had Micro – Chess going on the Mimeo and Dave Ahl’s HI-LO in tiny SCELBAL (integer BASIC) on the SCELBI. It was busy almost the whole day, just a few fairly brief periods between visitors. It seemed a bit busier than Saturday at VCF.

    HI-LO was the perfect text game for casual visitors of all ages – simple to teach and quick and easy to play – I was impressed by the number of small kids that immediately proceeded to use a binary search algorythm to find the number.

    A lot of people tried a few moves on chess, but the user interface is so awful on the Apple 1 port of micro-chess – I had to train almost everyone – even though I had instructions posted.

    I met an original Mark-8 owner(still has his system). That guy added a digital group video card to his Mark-8 and made some improvements to it, which were used by later generation Digital Group video cards. Another person who was into SWTPCs in the day. Another person that was once vice president of the Boston Computer Society. And finally, another guy who worked with Draper Labs on the Apollo guidance system computer.

    There was a wide variety of exhibits from art and crafts to a young man who was building a neutron generator. If you have a mini-maker faire in your area, I’d say it would be worthwhile to show off your gear – you might meet some interesting people.

    why is everything breaking?

    Monday, August 11th, 2014

    Within the last few weeks I’ve had the following problem with mechanical devices.

  • rear hub on bicycle
  • crankcase gasket on lawn mower
  • 3TB hard drive used for backup for three household computers died
  • coolant leak in 2009 Dodge Caravan
  • and a CD/DVD drive on a PPC Mac mini used for backup and connection to old peripherals is showing signs of imminent failure
  • My son says that I am having problems because all my stuff is old.

    Except for the the coolant leak, I’m getting replacement parts and doing my own repairs/replacments. I’d probably look the coolant leak, except that I just finished replacing the crankcase gasket on the lawn mower engine, and don’t feel like diving into another engine right now.

    I’ve had a lot of issues over the years with the lawn mower which was built in 1994 and would replace it with a new one, except that repairing it is so much less expensive than replacing it. For instance, the crankcase gasket, PTO oil seal, and a welded muffler (which I found was busted when I pulled the engine to repair the crankcase gasket) cost me all of $35 to repair or replace. That wouldn’t even pay the taxes on a new mower.

    When I pulled the crankcase cover off, I was expecting to see an engine on it’s last legs, but the internals looked good. Over the last couple of years, it was using a lot of oil, and I was thinking that the rings were going, but now I think that the oil was just leaking out of the crankcase. Now I think that the engine might last a few more years.

    Keyboard Gizmos

    Tuesday, July 15th, 2014
    parallel keyboard gizmos

    parallel keyboard gizmos

    Here is a popouri of parallel keyboard projects that I have been involved with designing.

    Not shown

  • A simple single chip AVR PS/2 to parallel keyboard adapter that I forgot about when I assembled the items for this picture.
  • At top is:

  • A reproduction Datanetics keyboard
  • At bottom, from left to right…

  • Home etched/prototype PS/2 to parallel keyboard adapter
  • Production PS/2 parallel keyboard adapter configured for Apple 1/Mimeo
  • Production PS/2 parallel keyboard adapter configured for Apple ][. The latest version firmware can also be used with other vintage computers
  • Home made Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch – based on schematic at Wendel Sander’s Apple 1 site
  • Production Vintage Micros Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch. Similar to home made one
  • Corey Cohen’s parallel keyboard multiplexor. Automatically accepts and switches input from two different parallel keyboards to a single destination motherboard.
  • Not shown are a number of projects that I have started, but not completed (yet)

  • Datanetics replacement using modern components
  • MM5740 replacement using modern micro controller
  • And then there are the projects that never got past investigation stage.

  • ADB bus to parallel adapter
  • PS/2 Apple IIe keyboard adapter
  • It’s really hard to imagine that I have spent so much time mucking with simple parallel ASCII keyboard technology.

    Model Rocket Launch Circuit

    Saturday, July 5th, 2014

    A few years ago I built a launch controller for Estes type model rockets. This was designed to be powered by a 12 volt battery. I usually use a battery off a riding lawn mower or motorcycle. When I was a kid I used to use a motorcycle battery that had a bad cell to launch model rockets and it worked great.

    complete launch control

    complete launch control

    This controller has two cables that are used to carry power from the battery to the ignitor.

  • A pair of clamps at the end of 10 feet of cable are used to connect to positive and negative terminals of a 12 volt battery.
  • A pair of small alligator clips at the end of 20 feet of cable are used to connect to the rocket engine ignitor
  • launch controller

    launch controller

    This controller has the following features.

  • A 1/4 inch phone jack used as a safety key. With the plug removed from the jack, the power is disconnected from the ignitor circuit.
  • A two color green/red LED – The LED’s red light is lit when power is available from the battery. The LED’s green light is lit when the safety plug is installed and power is available. Since both LEDs are lit when power and safety plug is installed, the resultant light looks yellow.
  • A green LED that lights up when power is available, the safety plug is installed and the ignitor is connected.
  • A red button that will launch the rocket if all LEDs are lit.
  • Now the reason for this post. The last time I used this controller, I did have a rocket launch imediately when I inserted the safety key. The LED that indicates that the ignitor is connected was designed to draw 10 milliamps through the ignitor and that current is flowing when the safety key is inserted. Though I tested that current through a number of ignitors, it must have been enough current to fire the one that went off prematurely. What I have decided to do was to substantially reduce the test current through the ignitor. The easiest way to do this was to use a smaller test current through the ignitor and use a transistor to amplify the current to a level high enough to light the indicator LED.

    Here is modified schematic. By the way, don’t bug me about the LEDs which are shown connected backwards in this drawing.

    launch controller schematics

    launch controller schematics

    With this design the test current through the ignitor can be roughly calculated as:

    12 volts/100000 ohms = 120 micro amps

    I think that this tiny current would be extremely unlikely to launch a rocket inadvertently. I measured the current through the LED as about 30 milliamps. This means the transistor is multipling the current by about 250 times.