Flex View A video monitoring
system.
A friend was selling PC's to a telephone survey outfit, and mentioned
the complex wiring system required
for monitoring the people doing the surveys. They were using banks
of mechanical/electrical security
switches. Each PC's CGA composite-out was cabled to a switch, which
had one monitor attached.
This was a lot of monitors and switches, not to mention the large number
of long video cables. Their
contracts required monitoring a percentage of the surveys, and with
64 PC's on 8 switches and 8 monitors,
it was very hard to keep things organized.
I designed a system using 9 RCA crosspoint chips, which allowed up to
64 PC's to be monitored. The customer
liked it, but wanted smaller ones for other sites, so I re-designed
it to support two keypad controllers and up to
24 stations. This was my first attempt at PCB design too. It worked
OK, I only had to change a few wire runs,
but it went together a lot faster than the hardwired one! The controllers
sat in the survey room which kept the
cable to each PC shorter and didn't require any holes in the wall.
An 8031 was used to control the box.
The Keypad/LED was made from an old Atari numeric keypad. An 8031, EPROM,
Drivers for the two Numeric LEDs,
and a Max232 were installed on a small PCB and inserted under the mounting
frame of the keypad. It used an external
power source, and was connected to the controller with an RS-232 cable,
which allowed the supervisors to set up in
a separate room. Each supervisor station needed only a keypad, and
a monitor, and only two cables to the controller.
The keypad allowed scanning rates of 1-99 seconds, and any of the stations
could be locked out or in. An added "feature"
was the switching time was reduced, and because of the video AMPs providing
a light loading on the PC, the survey
operators couldn't tell when they were being monitored. The audio monitoring
was provided by the telephone company.
This was a very nice moneymaker. After selling three of the smaller
ones, I recovered all my development costs,
which included a programmer and O'scope, and was able to buy the parts
to build other projects, and a better PCB
CAD program.
LCD Wall Plac (An Electronic Postcard?)
I worked on a DOD contract at SAC HQ, now called USSTRATCOM. It was a joint command, so my customers were from all branches of the service, including foreign military. One local tradition they have is an unofficial goodbye lunch or dinner. Everyone who is someone makes a speech, or lets everyone know how happy they are to see them go. Many gag gifts are presented, and also serious things to keep as mementos. A picture or Plac is a common one, and everyone signs it. ".
I decided that a Plac with over 200 names was too messy, and scrounged up the parts to make a computer-controlled Plac using a diagram of the network.
The CPU and display was started by pushing a button mounted through a hole in the Network Control Center on the Plac. The display started by displaying the Org name, his rank and name, and the date. After a delay it displayed a "Best Wishes in the Future From..." message on the second line, and then another delay. Then it displayed a depatment name and ran through everyone's name in that department-with a short delay between names, leaving the title line alone. This continued through all 220+ names + Orgs, and then it shut itself off. The battery and PCB were mounted behind the Plac, but I had to make a frame. Nothing I could find was deep enough to hide the parts shadow boxes were not made to be displayed backwards! I spent more time making a nice frame than I did programming the 80C31. I made up for it by making my office, and names display longer than the rest!
The code for the 80C31 is in the download section, if you want to see some quick/dirty code to talk to an HD44780 , the time-delay code, or even the addressing and positioning routines-which hide the control and addresses in the display data.
My Yaesu FT-757 provided a serial port which could be connected to a
computer for remote control. This was OK at
home, but I also took it along on "camping" trips. (An RV is not camping!)
After developing the PC version of a control
program, I just ported the major functions to a keypad controller.
While I was developing it, commercial versions were
being offered in QST ads, but none of them had digital displays, or
included the functions I wanted, so I kept building.
The result was an 80C32 with a 16-key keypad and LCD display. When I
finished adding all of the features I wanted,
I filled the rest of memory with frequency memories. I could scan ranges
in 100HZ steps, or more. Select memories in
the FT, or from the keypad controller. I ended up adding everything
that was supported by the FT. With some EPROM
room left, and time on my hands, I added the speech chip and speaker
for those dark nights! No, I had an idea it would
make a good article for QST, and HANDI-HAMS, but before I wrote the
article, GI stopped production of the chip!
I did have fun with it until I sold the FT!
Packet Radio. I used my computer for too many things, so when
I wanted to monitor packet, I had to stop doing
everything. A small LCD display worked just fine to read the mail,
and it evolved into my terminal.
Serial to Parallel Printer interface. Why I continued to use
parallel port devices after blowing all my ports, I'll never
understand. But when you need a printer... It was a fun project, and
I learned a lot about printer interfacing. I also
reversed it and ran my HP-Plotter off a parallel port!
