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k1.dyndns.org / Develop / Hardware / K1-Computer / K1-CPU 16-16 / Case / |
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k1.dyndns.org / Develop / Hardware / K1-Computer / K1-CPU 16-16 / Case / |
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Work-in-progress – I'm currently reworking the project pages!
Some text on this page is in German only.
It will be translated to English some time later.
Last updated: 2009-11-06
Questions & comments to Kio
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2009-02-18: Bevor ich mir wegen mangelhafter Spannungsversorgung noch ein paar ICs auslöte, habe ich heute die Spannungsversorgung auf einer Streifenrasterplatine zusammengebaut. Sie besteht im Wesentlichen aus einem DC/DC-Wandler von Syko, den ich zufällig mein Eigen nenne. Diesen kann ich mit fast allem, was sich Gleichstrom nennt, füttern, und er liefert mir dafür 5,1 Volt. Das Teil ist wirklich sehr nett: Es hat Feedback-Eingänge für +5V und GND von der Platine, um den Spannungsabfall über das Versorgungskabel und die Sicherung zu kompensieren. Für das +5V-Feedback habe ich ja schon einen Pin auf dem Anschlussstecker an der Platine vorgesehen, GND-Feedback entfällt leider wegen nur 3 Pins. Dafür habe ich das GND-Feedback am Wandler ein bisschen missbraucht, um noch knapp 0,1 Volt mehr aus ihm herauszuquetschen. Damit liegt die Spannung an der Platine dann bei ca. 5,15 Volt; postulierten Spannungsabfall über die GND-Zuleitung eingerechnet. Lieber ein bisschen zuviel als zu wenig, das rechnet sich später in Kilohertzen erhöhter Taktfrequenz. B-)
2009-05-04: First shots of the computer case, made from different kinds of wood:
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The front panel PCB is called 'SLOMO', because it provides 3 sources for slow motion / single stepping: A rotary switch for single stepping, a 1 to 100 Hz slow-motion clock and a port for a Atari ST mouse which i hope serves well for single stepping (moving it slowly) or skipping with a 'fast' clock (moving it rapidly). I was tempered to create a microcontroller-based design, which would offer more options for control. But finally i decided to stick to my initial design with 74HC circuits, to keep the design consistent. The PCB is single-sided, so i can produce it myself.
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And finally a scan of the board, made with my Agfa SnapScan:
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My component drawing for the key switch is not correct: the solder pads are at wrong positions. I have fixed it by patching the switch, bending away the pins and soldering wires which i stick in the displaced holes. I'll have to glue the switch on the PCB or it won't stay long.
Most of the circuit worked out of the box. I just had to change the resistors and capacitor for the slomo clock, because i had bought a 10k poti where it should have been a 100k one, and on test the slomo clock did not work. Measurement of the output voltage showed that the output of the opamp toggled between 1.9 and 4.4 volt. The low voltage was not low enough for the following schmitt trigger input to toggle. Two more resistors, one in place of a wire (yeah!) shifted the output into a working range.
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The circuit is pretty simple, but has a nice feature: It does not generate spurious pulses when you switch between clock sources. E.g. you can switch between single stepper and mouse without any unwanted pulse. The method is to convert any input clock into a short pulse when it toggles. This is done by splitting the signal, delaying one slightly by a RC delay circuit and rejoining them at an exclusive OR gate. Normally the inputs to the final mixer are all low, only when the source of the enabled clock toggles there is a short high pulse which flips the final 74HC74, used as a 1:2 divider.
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2009-09-12: I have tested my mental rugginess and designed the front panel in Open Office. Keyboard still intact, i'm still alive. Hah, i survived Open Office!
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| Name | Letzte Änderung | Länge | |||
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Images/ | 2009-11-06 10:39 | 3 | ||
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SLOMO/ | 2009-11-06 10:40 | 8 | ||
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case.vh | 2009-11-02 16:24 | 3927 | ||
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Wako SRI-E DC_DC Wandler.pdf | 2009-11-05 20:55 | 152939 |
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