Remote Relay Bypass System (GEOFEX)

[rustylee]

I'd like to build the Remote Relay Bypass system by R. G. Keen.  I see the comments on the site for this project state the project is still under development and indicates that packaging the system is pending.

If the project works as is, I'd like to build one of these if "under development" merely means it's not final, but the circuitry works.

Does anybody know if the circuitry works?  I'm referring to the following pages:

http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm
http://www.geofex.com/Article_Folders/remoteftsw.pdf
http://www.geofex.com/Article_Folders/remote.pdf
http://www.geofex.com/Article_Folders/pffootsw.pdf

Thanks,

-Rusty

[R.G.]

There was someone building one a few months back. Maybe they'll pop in.

The individual portions of the circuit work. That is, the path of switch to schmitt trigger inverter to latch to driver to relay works, and has been tested on the bench.

The reduction of all that to the specified chips and pinouts, and the traces on the PCB drawings have not been tested, in that I have not built one of those PCB's. It could be that there's a trace missing or misrouted, there may be a cut-and-paste of a wire or two.

There is a known bug in the PCB layout for the first reference in the list you cite, as the relay pinout is different.

The last three are part of single set.

As I mentioned, the relay and drivers are from a working setup I use all the time. Anything that flips the voltage at the input of the driver turns the relay on/off. The remote indicating control buttons are lifted from another circuit that I've used before. I built one "channel" of the thing on a breadboard, and it worked fine.

The PCB may need tweaked, but I don't know of any flaws in it yet. It would help me if someone traced through it to verify it. It's very hard to check your own PCB work well.

[rustylee]

Hello R.G.,

I've been looking intently at your plans.  I've been studying your narrative on the design.  I've taken a glance at your PCB design since I'm more interested at this time in experimenting.

I'm unclear about how the CD40106 fits since I see conflicting information in the narrative within the narrative itself, with the PCB design, and with the Conceptual Design ( http://www.geofex.com/Article_Folders/pffootsw.pdf ).

The narrative ( http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm ) states that, for six channels, two CD40106 triggers are needed, "Making that would require the indicating remote to use three CD4013's and two CD40106's (or CD4584's)[/b], with six pushbuttons, six LED's, etc."  This is consistent with the Conceptual Down.  However, further down it says:

Loop Switching Box Design

This box has to contain:

Guitar input and amp output jacks
-Six pairs of FXinput/FXoutput jacks, one per loop
-Six relay driver/relay/LED circuits
-Wiring and connections to hook up the remote switcher to the relay drivers

Remote Indicating Switch Box Design

The box has to contain:

Six momentary pushbuttons
Six input inverters ( contained in one CMOS CD40106 IC)
Six latches (contained in three CD4013 dual latches)
Wiring to get to/from the remote box.

The latter text seems to be consistent with the PCB layout illustrated on the same page.

To simplify this in my mind, at this time I'd like merely build one switching channel.  Does there need to be a second trigger on the relay side of the system?

Thanks,

Rusty

[R.G.]

I have this personal problem. I have a higher internal output capability than my output buffer can hold. It comes up in all kinds of ways.

In this case, my internal buffer was holding the idea that there were two CD40106's in the unit, and that overwrote the number of 40106's in the output buffer.

The schematic in http://www.geofex.com/Article_Folders/pffootsw.pdf is correct, I think. One CD40106 works for up to six loops on the remote footswitch unit.

You need one other CD40106 at the relay box as a receiver, total of two 40106's for up to six loops. I was obviously adding up parts lists in my head as I typed.

So the remote box contains ONE CD40106. This cannot be the same as the ONE CD40106 needed for the relay driver side in the relay box because the point of the two boxes is to be able to separate them. There is a total of TWO CD40106's needed, one per box. You will need at least ONE CD4013 in the remote switching box.

The local switch on the relay box that forces the relay on or off is not mandatory, and the remote box works without it.

[rustylee]

R.G.,

I thought it might have something to do with the input/output buffer :wink:

Thanks for clearing that up.  My parts should be arriving tomorrow.  I ordered two of the CD40106, figuring if I only needed one, I'd have an extra.  At $.50/ea., it's not like I was going to break the bank.

I'll let you know how it goes.

P.S.  I've got a wall-mount rack from work - we sell structured cabling equipment - so my plan is to build the switch using your idea about contructing the box with steel studs.  (I'm too cheap to buy a rack system from the music store.)  I will be rack-mounting my effects and the switch/bypass system.  Should be tons of fun.  I can get ahold of 25 guage studs easily.  The Unimast site doesn't work so finding a distributor in the L.A. area is going take a bit of legwork.

-Rusty

[rustylee]

Since I don't have a relay or LEDs yet, and since I'm anxious to test the circuit, is it possible to test the flip flop action with the circuit as-is without the LED or relay load?
-Rusty

[R.G.]

Since I don't have a relay or LEDs yet, and since I'm anxious to test the circuit, is it possible to test the flip flop action with the circuit as-is without the LED or relay load?

It sure is. Just do the switch/inverter/flipflop part. You may want to hook a 4.7K resistor + LED right to the output of the flipflop to show the status.

The inverter/transistor/LED/relay is a pretty reliable circuit for what-comes-in-goes-out. You should be able to get the whole remote box running without worrying about the relay setup.

[rustylee]

R.G.,

I don't know if my LEDs meet the 2ma-pull specification.  Would testing with any ol' LED be ok, or should I use a volt meter to determine if the flip-flop action is working?

[R.G.]

Use what you got and set it so you only put 2ma through them. If you're running from 12Vdc, use a 10K resistor for 1ma, 5.1K or 4.7K for 2ma.

[rustylee]

R. G.,

Thanks for your help so far.  This project is fascinating and fun.

I'm ready to just go ahead and order the stuff from Mouser.  I've referred to the http://www.geofex.com/Article_Folders/pffootsw.pdf document as well as the parts list for the remote relay circuit board at the bottom of the http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm document.

There are some differences in the guitar mounted switch that I'm not certain about, like the use of SPST switches vs. alternate action SPDT switches.  I don't know how C4 - C9 are utilized.  Also there are a couple of electrolytic caps on the remote relay switch circuit board that do not appear on the pffotsw.pdf schematic, though there is a callout for a 100mf electrolytic.  Perhaps there's a relationship there that I'm not seeing.

Here's my BOM from Mouser (for a single channel effect switch - I'll get the rest when I get one channel to function:

2ea: 511-40106
ST 5V Logic (HCF4xxx, M74HC/HCT, 74AC/ACT, 74VHC/VHCT)
DIP-14 HEX SCH TRIG
 
3 ea.: 511-4013
ST 5V Logic (HCF4xxx, M74HC/HCT, 74AC/ACT, 74VHC/VHCT)
DIP-14 DUAL "D" F/F

2ea.: 550-20311
Neutrik/Rean 1/4' Phone Jacks
3C STEREO 3-SPST NC

2 ea.:  550-1005
Neutrik/Rean 1/4' Phone Jacks
PLASTIC NUT

1 ea.: 551-ED2-12NJ
NEC Miniature Low Signal Relays
12VDC NON-LATCH

1 ea.: 625-2N3904
Vishay Semiconductor Small Signal Transistors
TO-92 NPN General Purpose
 
2 ea.: 78-1N914
Vishay Semiconductor Small Signal Diodes
DO-35 100 Volt 300mA T/R

10 ea.: 291-4.7K
Xicon 1/4W 5% Carbon Film Resistors
1/4W YW,PR,RD,GD

1 ea.: 140-XRL25V4.7
Xicon Radial Electrolytic Capacitors
25V 4.7uF 20%

1 ea.: 80-C315C104M5U
Kemet Conformally Coated Radial Ceramic Capacitors
50V Z5U 0.1uF 20%
 
1 ea.: 140-XRL25V47
Xicon Radial Electrolytic Capacitors
25V 47uF 20%

2 ea.: 604-L53SRCDU
Kingbright Super Bright LED Lamps
T1 3/4 T-1 3/4 LAMP RED CLR

1 ea.: 140-50S9-102J
Xicon Ceramic Disc Capacitors
50V,SL,1000PFD,5%

1 ea.: 611-8168-201
ITT Cannon (C&K) Pushbutton Switches
ON-(ON) SPDT SOLDER
 
10 ea.: 291-100K 291-100K
Xicon 1/4W 5% Carbon Film Resistors
1/4W BR,BK,YW,GD

10 ea:. 291-10K 291-10K
Xicon 1/4W 5% Carbon Film Resistors
1/4W BR,BK,OR,GD

Power supply stuff (already have the transformer):
1 ea.: 526-NTE1970
NTE replacement Voltage Regulators
TO-220 +12V 1A

4 ea.: 583-1N4002
Rectron Rectifiers, Silicon
DO-41 1A, 100 Prv
 
1 ea.: 140-XRL25V470
Xicon Radial Electrolytic Capacitors
25V 470uF 20%

1ea.: 140-XRL10V470
Xicon Radial Electrolytic Capacitors
10V 470uF 20%

[R.G.]

I'm ready to just go ahead and order the stuff from Mouser. I've referred to the http://www.geofex.com/Article_Folders/pffootsw.pdf document as well as the parts list for the remote relay circuit board at the bottom of the http://www.geofex.com/Article_Folders/rmtswtch/rmtsw.htm document.

Do remember that those two articles are similar, but not exactly the same. They are not intended to match one for one, even though the circuits are almost identical. They are two different adaptations of the same concept.

The guitar mounted switch setup was one I did for a fellow who could not easily use a stompswitch setup, so he could put the switching on his guitar.

The floor mounted unit was done for a more mainstream stomping setup.

There are some differences in the guitar mounted switch that I'm not certain about, like the use of SPST switches vs. alternate action SPDT switches. I don't know how C4 - C9 are utilized.

The two switch setups were specific to the uses. The momentary switches on the guitar-mounted setup were to be able to use the very small momentary tactile switches. The circuit actually wants a momentary switch. In the guitar mounted circuit, the switch shorts out C4-C9 as appropriate. The switch bounces, but because the cap was discharged to zero by the first "make", it has not charged up very much through the resistor. When the switch stops bouncing, the cap can then charge back up to +12. The schmitt trigger in the inverter cleans up that fast-down/slow-up signal into a logic pulse that triggers the flipflop.

However, in the floor mounted setup, I used a trick I saw in Kevin O'Connor's TUT to use an alternate action switch as a momentary by wiring both throws of an SPDT switch together and using the momentary open time while the pole is switching between throws and not connected to either one. It's still a momentary switch, but it reliably produces one open/close cycle when it's pressed, and your foot can feel the -*clik*- when the switch flips over, so you get tactile feedback that it's done it's thing.

In this variation of the switch trigger circuit, the debounce cap is held normally shorted by the switch. When you press the switch, it opens for a few milliseconds between the throws. That lets the debounce cap ramp down, pulled by the resistor.  When the switch re-closes, it bounces, but again, the first make shorts the cap and further bounces are so fast that they don't make more pulses. The schmitt trigger again cleans up the switch/cap stuff into a clean logic pulse to trigger the flipflop.

Also there are a couple of electrolytic caps on the remote relay switch circuit board that do not appear on the pffotsw.pdf schematic, though there is a callout for a 100mf electrolytic. Perhaps there's a relationship there that I'm not seeing.

It's probably simpler than that. I believe that those are all power supply decoupling caps, intended to keep the +12V power supply buss quiet.

Power supplies are intended to be sources of pure DC, as near an ideal voltage source as possible. Running voltage supplies over long wires makes any power supply less ideal - there's the wire resistance, the inductance of the power supply/ground loop to pick up radiated junk, and the self-inductance of the wires. It's good practice to swamp out all that with local capacitors wherever you have either
a) an isolated chunk of circuitry remote from the power supply
b) noisy user circuits, which use a lot of power relative to the other circuits, especially if it's intermittent - like the LEDs and relays in this case
c) switching circuits with fast edges.

I'm fairly casual about decoupling. I put some in to every circuit I do, and worry more about it if one of the above situations arise. If I do something like a fast-switching logic array, I'll spread decoupling caps of various values (to take advantage of the different ESR/ESL/dielectrics) around to keep the power supply impedance down locally.

So, yeah, they don't match exactly. Pick one.

Here's my BOM from Mouser (for a single channel effect switch - I'll get the rest when I get one channel to function:
...
1 ea.: 611-8168-201
ITT Cannon (C&K) Pushbutton Switches
ON-(ON) SPDT SOLDER

That switch is going to work OK, but it will be flimsy for foot-stomping use.

I think you'd be happier with the new Xicon/Alpha pushbutton footswitches that I found at Mouser. They're 107-SF12020-L or 107-SF12020-M. These are DPDT latching (-L) and momentary (-M) foot switches and cost $4.95 each.

[rustylee]

R.G.,

Thanks for your careful explanation.  Obviously I'm a newbie, so much of this stuff goes over my head.  I'm trying to learn this stuff through osmosis, or immersion.

I'll order the switch you recommended.  I was trying to keep to the "alternate action" specification.  I'll assume this switch is interchangeable with an "alternate action" switch with no mods.

Cheers,
Rusty

[R.G.]

Steve Daniels posts that Mouser doesn't really have any of these, so check stock first. They're supposedly coming in sometime.

[jhergonz]

Goodday guys, I want to use this Mr. RG keens' remote switching circuit in one of my builds. just wanna ask if once one loop's switch is engaged/turned on, does the other turns off automatically? and also. is it possible to use 9v DC supply in the circuit? then use 5v regulator and relay?