[sci.electronics] NEED SIMPLE HELP PLEASE!!

v127l2qz@ubvmsb.cc.buffalo.edu (Shane P Faulkner) (10/17/90)

I'm really not very good (yet) with electronics, and I need a solution to
what seems to be a simple problem.  I'm a guitar player and I have 2 switches
to control my system.  One is a momentary switch to switch programs on my 
effects unit.. when I press it down and release it, the program gets changed.

The other switch is an on-off type switch to change the setting on my amp
from clean to distorted.  What I need is a third switch... an on off switch
that also acts as momentary signal to my effects unit... for instance if
I was on the distorted channel on my amp, I would press this switch and it
would change the amp to clean and send the momentary signal to my effects unit
to change the program.  Then when I pressed it again, the amp would go back to
distorted and the program would change.

A simple explanation or schematic would be VERY much appreciated. I'm counting 
on the cumulative knowledge contained in this folder... !!

Thanks in advance... a reply here or via mail would be great !! 
-Shane Faulkner

deanr (Dean Reece) (10/20/90)

In article <41207@eerie.acsu.Buffalo.EDU> v127l2qz@ubvmsb.cc.buffalo.edu writes:
>I'm really not very good (yet) with electronics, and I need a solution to
>what seems to be a simple problem.  I'm a guitar player and I have 2 switches
>to control my system.  One is a momentary switch to switch programs on my 
>effects unit.. when I press it down and release it, the program gets changed.
                                     ^^^^^^^^^^^^^^
>
>The other switch is an on-off type switch to change the setting on my amp
>from clean to distorted.  What I need is a third switch... an on off switch
>that also acts as momentary signal to my effects unit... for instance if
>I was on the distorted channel on my amp, I would press this switch and it
>would change the amp to clean and send the momentary signal to my effects unit
>to change the program.  Then when I pressed it again, the amp would go back to
>distorted and the program would change.
>
>A simple explanation or schematic would be VERY much appreciated. I'm counting 
>on the cumulative knowledge contained in this folder... !!
>
>Thanks in advance... a reply here or via mail would be great !! 
>-Shane Faulkner

You say that: "when I press it down and release it, the program gets changed."

If this is exactly the case (the changeover occurs when the contacts are
RELEASED), then there is a cheep-n-easy solution to your problem:

     ______     ___ 
    M   | |     |  L
        o o   o o
         /- - -/
         o Sw1 o
    M____|     |___L

Where Sw1 is a DPDT center off type switch (typical is RS# 275-664). The way
this circuit works is that the Momentary contacts (M) will be broken while
the switch travels from one extreme to the other.  The Latched contacts (L)
will go to your amp.  Just avoid leaving the switch in the center position,
as it will yield a third state to your system when switched from left to right
as shown above (contacts to amp off, but the program will have been changed to
the mode that expects the amp contacts to be on).  Manual over-ride (your two
existing switches) could be implemented by adding a momentary Normally CLOSED
switch in SERIES with the M contacts; and adding an SPDT toggle to the 'L'
contacts of Sw1 as shown for Ry1 at the end of this posting.

If the momentary contacts MUST be open during normal operation, then the
following circuit wil absolutly work but since it uses relays, it will
need some sort of power supply (12vdc or 6vdc would be ideal, avoid 120vac):
                 __________________________________
     ______     |  _________     _____    _        |
    M   | |     | |   |     |   |     |  | |       |
        o o Sw1 o o   |   o o o o Ry1 |  | o o Ry2 |
         |- - - -|    |    \- -\- - - |  |  \- - - |
         o       o    |    o   o (((( |  |  o (((( |
    M____|       |__P | P__|   | |  | |  |  |_|  |_|
                      |        L |  | L  |   | 
                      |__________|  |____|   G
Parts list:

Sw1: DPDT Momentary Center Off type switch (like some auto-power antennas use)
Ry1: DPDT relay, coil to match whatever supply voltage is handy (say 12vdc)
Ry2: SPDT relay, coil to match whatever supply voltage is handy (say 12vdc)

The points marked M are the Momentary outputs; The ones marked L are the
Latched (on/off) outputs; and P and G are Power and Ground.  All contacts
are shown in the relaxed states.

Ry1 is rigged in standard Latching configuration.  When Sw1 goes to the right,
a power pulse is applied to Ry1's coil.  Ry1's contacts close, latching the
path from power to the coil. This path can only be broken by Ry2's contacts
going open.  This is done by energizing Ry2's coil (moving Sw1 to the right).
Ry2 can be eliminated if you can get somewhat more exotic switches
(3P3T momentary center off w/make before break contacts, perhaps rotary style)

You could add manual over-ride to this circuit (your 2 existing switches)
very easily:  Just put your momentary switch in parallel with the M contacts
and modify the 'L' contacts of Ry1 as shown below:
      ______
     |      L
     o
     \ <- add this SPDT toggle switch
    o o
    | |
    o o Ry1
     \- - -
     o ((((
     |______L

There are some solid state solutions, but this is more robust.  Hope it helps!

-deanr@sco.com (Dean Reece)