🚀 go-pugleaf

In article <2047@mountn.dec.com> hutzley@bigq.dec.com (Steve Hutzley) writes:
-
-    I was wondering if anyone could help me with a project I'm trying to put
-    together.
-
-    I'm sure by now, that everyone has seen the christmas lights that CHASE
-    (this I belive is the theatrical term for it)...The kind of lights that
-    have the following sequence..
-
-        1000
-        0100
-        0010
-        0001
-
-        and repeats continiously, at a set rate.
-
-        I know this can be done with TTL, driven with something like a 555.
-        but have been unable to make it work. I have one of those "light in
-    motion" strings at home, and have tried to reverse engineer it with no
-    luck.
-
-    I have the solid state relays that I plan on using, that are driven
-        by 3-32 VDC and will handle 240VAC @ 10A.
-
-
-        Anyone want to help in this venture?
-
-Steve_with_no_sig_file


I'll take a stab. Note that this is from memory, and I don't have a
ttl databook in front of me.  (Meaning signal levels may be upside down.)

                     -----
                    |     |--15
         ----       |     |--14
        |    |      |     |--13     ---|
-----   |    |--A3--|  7  |--12     ---|
|555|---|7493|--A2--|  4  | .       ---| --- To solid-state relays.
-----   |    |--A1--|  1  | .       ---|     (Signals are active low).
        |    |--A0--|  5  | .       ---|
         ----       |  4  |--3
          |         |     |--2   <------  Reset line from counter
          |         |     |--1         |
          |         |     |--0         |
          |          -----             |
          |                            |
          ------------------------------
Here's how this works:
  The 555 generates pulses at the step frequency of the lights. These pulses
cause the 7493 counter to advance from 0 to 15 in binary on the A3-A0 lines.
These binary numbers, when fed into a demultiplexor, cause each discrete out-
put line on the demux to go low one at a time.  The solid state relays are
activated by the output lines of the demux, causing (at most 16) lights to
chase.  If you wish to use more lights, hook subsequent sets of lights in
parallel with the first set, which will allow several lights to seem to chase
each other.  If you want fewer lights/string, hook the reset line from the
counter to the n+1th output line of the demux. This will cause the counter
to reset when n lights have been sequenced. Examples:

--O0-----SSR-----------()--|  L0
                  |        |
--O1-----SSR-----------()--|  L1
                | |        |
--O2-----SSR-----------()--|  L2
              | | |        |
--O3-----SSR-----------()--|  L3
            | | | |        |
            | | | -----()--|  L4
            | | |          |
            | | -------()--|  L5
            | |            |
            | ---------()--|  L6
            |              |
            -----------()--|  L7
                           |
                         -----
                          ---
                           -

With this setup, and the reset line on O4, the following will happen:

L0 L1 L2 L3 L4 L5 L6 L7 
*  .  .  .  *  .  .  .
.  *  .  .  .  *  .  .
.  .  *  .  .  .  *  .
.  .  .  *  .  .  .  *

If you want every other light to chase, hook lights to O0 and O1, reset to O2,
and parallel sets of lights from there. That will yield:

L0 L1 L2 L3 L4 L5.....L99 L100
*  .  *  .  *  .      .   *
.  *  .  *  .  *      *   .

with the hookup  ---O0---SSR------() L0
                               |
                 ---O1---SSR------() L1
                             | |
                             | |--() L2
                             | |
                             |----() L3
                             | |
                             | |--() L4
                             |
                             |----() L5

Be sure you don't exceed the power handling capability or you solid state
relays (SSR's), and be careful if you use high voltage bulbs.

If you have further questions, please don't hesitate to send me email at
davet@tsdiag.ccur.com.   I hope this helps you.
-- 
David E. Tiller         davet@tsdiag.ccur.com  | Concurrent Computer Corp.
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