[GreenKeys] TTY-Connect questions

[gil smith]

Hi Don/Charlie:

Comments below:

At 04:27 PM 7/4/2004, you wrote:
>>>A. sescom 2U rack.  19x2x7 I have used similar boxes (i believe 
>>>Hammond?) and they are assembled from panels to make either a rack or a 
>>>tabletop unit.  Would probably want this to be more than 7 inches deep 
>>>with plenty of clearance for transformers, etc., suggested panel layout 
>>>would be good.

The Sescom rack-mount box is nice for a couple of reasons:  a)  it has flat 
panels that slip into extrusions, so if you want to change a hole layout 
later, you can just change a panel,  b) the panels are 1/16" aluminum (not 
steel), so it is easy to drill and nibble holes,  c) they are available in 
a variety of sizes -- I happen to be using the 2U-high-by-7-inch-deep 
version -- if you want more room inside, get a bigger one, like10-inches 
deep.  But you can mount the unit in anything that strikes your fancy.

Note that the Sescom box's lower-rear extrusion needed to be notched where 
the two pcb mounting standoffs are located.  This is easy to do since the 
extrusions are also aluminum.


>>>B. printed out DWG for PWA assembly and it was cut off around 
>>>edges.  screen examination showed same thing.  can this be resized and 
>>>resent?  some dimensions for the PCB and mounting holes would be 
>>>good.  everything looks like non-surface mount (good) with the DIP 
>>>package for the CPU being the biggest

Well, that is all of the assembly drawing that is available in pdf 
form.  It is really only for the pcb components anyway, and the "cut-off" 
stuff merely shows tentative locations for transformers etc.  I keep all 
mounting hole and connector-centers on a 0.1" grid, to make it easy to 
quickly measure the board and transfer locations to the chassis.  Yeah, a 
dimensioned drawing for chassis holes would be nice.  Have not had time for 
such a thing.


>>>C. Are there pictures of a completed unit?  I assume a prototype must 
>>>have been
>>>assemblled and checked.

Files/pictures/docs are at:
http://www.vauxelectronics.com/gil/tty-connect/

Firmware doc is still not up-to-date.


>>>D. Optional parts.  An 83.00 LCD is shown.  How would this be used?
>>>We do not have source code so assume you are thinking about echoing 
>>>transmission characters but do not see this on schematic.
>>>I asume that it is a serial interface similar to stuff used for parallax 
>>>stuff.  I recall one for about 50.00 that had about 5 control line for 
>>>pushbuttons.

Well, the Matrix-Orbital lcd is not supported in firmware at this time, but 
the pcb has a header that provides the signals (it uses I2C, not a simple 
logic-level uart, like other serial lcds).  The objective is to provide a 
front panel control for the unit, and maybe a monitor mode.  But I am not 
committing to anything at this point (I should not have put the lcd in the 
docs at this point).  It is a nice lcd module, but don't buy one yet.  And 
a front-end on a PC would do the same thing.


>>>U20,U21 not shown on BOM but believe is same as U50,51.

U20 and U21 are in the BOM in the LV-Loop section (they are both 4N37 
isolators).  U50 is part of HV1 and is a 4N37, and U51 is also part of HV1 
and is a high-voltage H11D2 (do not substitute).


>>>E. there are several assembly options.  Don will have to select and define.
>>>Optional parts include various extras.  Sockets, etc.  I prefer sockets, 
>>>I do not think
>>>vibration will be a problem.

Yes, I would socket everything, including the 6-pin dip optos.


>>>Regards,
>>>
>>>Charlie
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