You can put the leds (with a resistor) parallel to the relay coils. Also put a diode parallel to the relay coils, anode to plus side. The pushbuttons should only make contact as long as you keep them pressed, like doorbell buttons. "N.C." are normally closed contacts, and "N.O." are normally open contacts.
I have not drawn the audio path, but hopefully you can figure that out yourself.
Thanks, Frank.
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R
Rich Webb
The logic can probably fit into a small GAL chip.
If sw-1 is pressed and remains pressed, should pressing sw-2 cause the outputs to change state? Should an error be asserted? Or should pressing any other switch be ignored if a switch is held in the active state?
Also, where are you debouncing? A switch is not synonymous with an effect; a switch is a whole lot of effects before it settles down to the new state.
Rich Webb Norfolk, VA
J
John Fields
--- OK, here ya go... view it with a fixed-pitch font like Courier.
All the resistors are standard quarter-watt 5% carbon film, The RS latches are cross-connected NORs, the diodes are 1N4148's, and the transistors can be anything that can handle the relay current and has good gain. 2n4401's would be good choices. For the relays I'd use five SPSTNO (form 'A') reed relays.
You'll have two NORs and an OR left over, and you need to make sure that their inputs are connected to +V or ground. It doesn't make any difference which, just don't let them float.
If your supply voltage is going to be higher than about 5V you'll want to use 4000 series CMOS for the logic, otherwise you could use either 4000 or HC74.
Also, the base resistors may need to change depending on your supply voltage. What is it, BTW?
When you reply, please leave a little of this post in your reply so we can see what you're referring to, OK?
Thanks,
-- John Fields Professional Circuit Designer
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John Fields
Oops... I forgot the LEDs. Here\'s a single channel, the others will
be the same:
+V +V
|A | IN OUT
[LED] +------+ | |
| |K | O-+ O-+
[R] [DIODE] [COIL]- -|-|- - - - - -| |
| | | O--> | | O--> | |
+-------+------+ | K1A | |K1B |
+V | +------|-[A]--+ |
| ___ +----+ C | |
+-O O--+---|S Q|-------+------[1000]--B NPN | |
| S1 | +-|R | | E | |
| | | +----+ A--|---+ | | |
| | +---------Y OR | | GND | |
The value of R will vary depending on your supply voltage.
Oh, and by the way, the bracketed \'A\' and \'B\' located between the
normally open contacts of K1 and K2 are what you call "section 1"
and "section 2" on your drawing.
The way the thing works is that when S1 is actuated, K1 energizes,
connecting IN to the input of \'A\' and the output of \'A\' to OUT,
while at the same time de-energizing K2 and K3, removing \'B\' and the
straight-through path from the circuit.
When S2 is pressed, K1 and K3 will be de-energized, disconnecting
\'A\' and the straight-through path from IN and OUT, while connecting
\'B\' between IN and OUT.
When S3 is pressed, K1 and K2 will be de-energized, disconnecting
\'A\' and \'B\' and enabling a direct connection between IN and OUT.
J
Jon
GoatBoy, Let a, b, c be the inputs A,B,C be the resultant outputs. a' = not a, b' = not b, c' = not c. * = logical "And" ~ Then A = a*b'*c' B = b*a'*c' C = c*a'*b' ~ This can be implemented with gates, relays, or a combination. You may have to debounce the inputs. Regards, Jon
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John Fields
After thinking about this a bit more, I realized that if reed
relays could be found which were sensitive enough, they might be
capable of being driven directly by the logic, eliminating the
transistors. To that end, it turns out that the spare gates can be
used in conjunction with the RS latch outputs in order to provide
more than enough current to drive COTO 9801-05-41 reed relays, which
have a 1000 ohm coil and only need 5mA from a 5V supply in order to
be energized. You\'ll also need to use 5V HC74 logic. The schematic
is too busy to do in ASCII and have it come out easily legible, so
I\'ll post something for you at abse sometime today.
G
GoatBoy
OK, here ya go... view it with a fixed-pitch font like Courier.
All the resistors are standard quarter-watt 5% carbon film, The RS latches are cross-connected NORs, the diodes are 1N4148's, and the transistors can be anything that can handle the relay current and has good gain. 2n4401's would be good choices. For the relays I'd use five SPSTNO (form 'A') reed relays.
You'll have two NORs and an OR left over, and you need to make sure that their inputs are connected to +V or ground. It doesn't make any difference which, just don't let them float.
If your supply voltage is going to be higher than about 5V you'll want to use 4000 series CMOS for the logic, otherwise you could use either 4000 or HC74.
Also, the base resistors may need to change depending on your supply voltage. What is it, BTW?
the LEDs.
F
Frank Bemelman
Well, for some reason I think dear "Goatboy" will have a tough time programming a GAL chip.
Thanks, Frank.
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R
Rich, Under the Affluence
Are you _THE_ "Goat Boy"?
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Isn't that name copyrighted? ;-P ;-P ;-P
Cheers! Rich
R
Rich Grise
So, you're saying, normally, your performer's guitar goes through the effects box uninterrupted, and unmodified, right? (that would be your "bypass" or "all off" setting, right?)
The performer steps on switch one, it engages effect one, and disengages effect two, right?
The performer steps on switch two, it engages effect two, and disengages effect one?
And when the performer steps on switch three, it disengages both effects?
We're only engineers here - we need stuff spelled out in little words. ;-)
Good Luck! Rich
R
Rich Grise
If you want the physical, mechanical actuation of one switch to disengage the other two switches, on a stage, with guitarists stepping on them, then you need something mechanical. My brother is a professional guitarist, and has been dicking with foot switches for about 20 years.
Tell ya what - I'll email Dan (my brother), and ask him what's available in the professional rock band milieu.
Well, if you ask me to. I don't want to bother him for something that you could get at the hardware store.
Let me know, M'kay?
Cheers! Rich
G
GoatBoy
John, I printed out the drawing you posted in ABSE. It looks good, about what I expected I'd have to do to make this work. Are the switches standard or momentary?
J
John Fields
--- Momentary. Once they set their peculiar latch their job is done.
I've decided to use the last OR to implement a Power-On-Reset so that the circuit will default to the straight-through mode on power-up and, since you'll be using a 9V power supply, to use a
78L05 to get that 9V down to 5V for the HC logic. I'll make the changes to the drawing and post "Rev A" sometime today.
-- John Fields Professional Circuit Designer
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