projects

Here you can find descriptions of some little projects like a small photoplethysmograph, a true random number generator, seismometers and things like that.

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An AVR-based video controller.

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Debugging and repairing a TM990/100M computer.

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Musings about TI's TMS9900 processor family.

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A really tiny Z80 computer.

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The odyssey of repairing a HP3330B.

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Restoring a wonderful PDP 11/34.

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In September 2011 I suddenly had the urgent need to build a small Z80 computer (my last homebrew Z80 was built when I was in school - more than 20 years ago!). See what came out of this. :-)

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My beloved wife Rikka showed my some "yarnmeters" which are used to measure the length of yarn. We decided that a homebrew yarnmeter would be nice and here you can see the result. :-)

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A couple of weeks ago I bought a wonderful but defective Fluke 8300A digital voltmeter for a mere 18 EUR in an online auction. This page describes my efforts to get this device up and running again.

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One of my beloved Telefunken OMS 811 oscilloscopes dies some time ago - no trace, nothing. This page describes how the device was repaired.

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Now having my own Rubidium based oscillator/clock, I was looking for a way to use this as my master reference, so what I needed was some clever way to compare the performance of different oscillators to this device. I was incredibly lucky when I had the chance to buy a Tracor 527E Frequency Difference Meter. This page describes the device and what was necessary to get it up and running again.

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Since being a child I have been dreaming about having my own atomic clock - not necessarily a cesium primary standard, but maybe a rubidium oscillator controlled device. This dream has now come true! :-)

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A small, Perl based, stack oriented array language called 5. This language combines the main aspects of Forth and APL and is easily portable as well as quite powerful.

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A new 16 bit processor architecture featuring 2056 registers (a bank consisting of 256 times 8 registers and 8 fixed registers), a very (!) orthogonal instruction set and four condition bit controllable branch and subroutine call instructions.

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Restoring an HP 41C programmable pocket calculator.

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Restoring an HP67 pocket calculator.

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A simple TTL modulated diode laser.

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A random noise filter.

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A control stick adapter for analog computers.

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Restoration of an Telefunken OMS 811 oscilloscope.

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A four channel oscilloscope multiplexer.

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Dragontalk - a simple Speech Synthesizer (not only for OpenVMS systems).

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An active DCF77 antenna.

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A simple power supply for a HeNe laser tube.

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The NICE pages.

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A three channel geophone amplifier

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A high resolution flux gate magnetometer

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A precision timing source for synchronizing AD converters, etc.

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A simple short period vertical seismometer.

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An eight channel AD  converter.

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A simple Lehman type seismometer and Some seismic events.

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A high performance amplifier for seismic applications.

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A simple power supply for the seismic amplifier.

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How to convert a DECserver 200 into a MIDIserver 200 and control MIDI-instruments from a VAX running VMS, using QIOs. :-)

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A simple but very useable photo plethysmograph for bio-physiological experiments.

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A random number generator using a Thorium radiation source.

 

 

ulmann@vaxman.de

webmaster@vaxman.de

27-AUG-2014