Hello All,Recently I tried making some custom SCSI cable. In the past I have successfully made my own 50pin SCSI and Floppy cables with out much issue. However, I am finding it almost impossible to crimp the HD68 connectors on the cable. I have even tried a vise grip and I still couldn't get it to crimp all the way down. Anybody with some advice? Is there a trick I am missing? TiA.
A little while back I posted here because I needed help with analysing the
failure of the PSU from my VAXmate. Since then I have had some comments on
the reverse engineered schematic which I have now improved and which is
Following advice from a list member, I have been looking at the 555 and the
PWM that control the switching transistor, using a bench power supply to
power the PWM directly (across pins 5 and 7). When I do this, I find that
Vref from the PWM, which should be 5V to power the 555, does not reach 5V. I
have tried removing the 555 from the circuit, and when I do this Vref goes
to the nominal 5V, once Vcc to the PWM is above 16V. However, if I put the
555 back in, then Vref only goes to 2V. I have socketed the 555 and tried
with two other brand new 555 chips, the result is the same.
It seems that just adding a 555 kills the Vref output of the PWM. It can't
be anything else in the circuit because everything else is still in circuit
when the 555 has been removed. Could the PWM be faulty? Perhaps it can't
provide enough current to bring Vref up to 5V once the 555 is in the
Any suggestions gratefully received.
I've got a couple of Teac FD-54B's that appear to have problems with their
index sensors. Does anyone have any docs for these? The internet seems to
barely know they exist vs the FD-55, which has info everywhere. I'm thrown
off a bit by the 3 wire phototransistor (vs the common 2 wire ones) they
they use, and I haven't quite disassembled it enough to figure out a part #
Also, if anyone has a pair of spare black FD-55B, that'd be useful too.
Classic heavy duty HP Designjet 755CM C3198B? in search of a new home as
it's now one stop short of the e-waste people.
It's large? (handles a 36in roll) and has the usual DesignJet stand.???
I can even include some NOS ink cartridges.
It would need a horizontal belt as they deteriorate even without use but
otherwise in good shape; it was fully functional when I removed it from
I'm not trying to sell it, I just hate to trash it.
Not easily shippable, it's located in the Santa Cruz area - I could
deliver it here in the bay area if someone wants it.
On this, the 74th anniversary of the unveiling of
the ENIAC, I've decided to post a couple of things
I've been working on. The first is the 3D model
of the ENIAC mentioned before. It's designed
using brlcad, from the Ballistics Research Lab.
It just seemed too appropriate to model it using
the tool devleoped where it lived. The
thingiverse link is:
The second thing is a draft of a chapter from a
book I'm in the very early stages of. It
describes the basic circuit designs used in the
ENIAC with SPICE simulations of them. The layout
and formatting are based on the old Army Technical
Manuals of the time.
P.S. Apologies if you got this multiple times; I've
posted it to a few lists I'm on.
Anyone here have a set of Sun external SMD cables (530-1079 and 530-1080) that they can loan or want to sell?
I ordered from a set from MemoryX at the beginning of Jan. They haven?t arrived and MemoryX isn?t answering my e-mail asking what?s up.
Ok offer me offlist for our extra transistor unused? in box sealed in original cellophan6...
Have extra ge. G11a. First GE landmark transistor for counter and computer cicurits
Germanium Whisker Transistors
Robert Hall returned to General Electric Research Laboratories Schenectady just as Bell announced its point-contact transistor.??Hall had just graduated PhD from Caltech and had previously worked at the laboratories on a range of projects including the Harper North Wartime radar diode project. Dr Albert Hull was Assistant Director of the Laboratory. He was known for his collegial management style with a relaxed approach to the research agenda of his staff members. Hall recalls that Hull came in with the reprint of the Physical Review letters that announced the transistor [Bardeen 1948] and said ?Robert here?s an interesting development from Bell Laboratories. It looks like something pretty new and exciting. Would you like to look into it and see if there?s anything interesting there.? [Choi 2004]
General Electric had all the knowhow it needed to duplicate the Bell design quickly. North?s diode programme had diodes that could handle 100 volts back voltage which was state of the art at that time. (Purdue University produced the high back voltage germanium for the Bell point contact transistor.) North?s diode programme and related research ensured it had a manufacturing understanding of the key technologies:
High back voltage poly-crystalline germanium;
Point contact design;
Welding or forming; and
Assembly and encapsulation.
Its first designs were crude with two pins for the collector and emitter with the base connection through the case in the manner of the Bell Type A. No socket was available and users were recommended to use a 5 pin subminiature tube socket using positions 2 and 3 for the collector and emitter and to create a base connection by inserting phosphor-bronze strips in positions 1 and 4 and bending them so they contacted the transistor case.
The transistors were known as germanium triodes or germanium whisker transistors. Two types were produced evolving from prototype coding through the familiar ?G? designation in use for its point-contact diodes and finally adopting RMA registration:
Up to 1951
The prototype numbers appear in early data sheets and in a General Electric price list dated June 1st?1951 in which the new SX-4A and Z2 transistors were priced at a massive $29 each.
The two transistors had the same mechanical and electrical characteristics but the switching transistor was tested for ?trigger action? or negative resistance. [General Electric 1950 courtesy Jack Ward]
>From 1952 the transistors had 3 pins with the base connection being soldered to the outside of the transistor?s case.
See data sheet ECG-3B.
Early General Electric G11 and G11A point-contact transistors.[Courtesy Jack Ward]
Production General Electric G11 point-contact transistor [Courtesy?Jan de Groot]