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previous: Jsh I tried to see if we could get away... -- 12/16/1999 6:59 PM

Re: The original thoughts

12/16/1999 7:27 PM
R.G.	Re: The original thoughts Ok, take a look at http://www.eden.com/~keen/fxselex.gif and http://www.eden.com/~keen/fxselex1.gif. fxselex.gif shows the footswitch. You use a momentary footswitch per "program". That is cleaned up by a CMOS schmitt trigger gate and is latched by a 74C373. The six diodes work the enable/latch whenever any one of the footswitches is pressed (released, actually) and only one footswitch gets latched in. So we have a bit that says "Program active" for each footswitch. The circuit actually supports up to eight, but you want one for turning all the effects loops off and having a complete bypass. fxselex1.gif shows the programming matrix. Each effects loop is controlled by a high level on +FXx_ON; the loop is bypassed when its +FX signal is low, and is enabled whenever its +FX signal is high. Each programming switch is one SPDT slide switch, three signal diodes and one LED/resistor as an indicator. The switch either grounds the LED, showing that the effects loop is active for that program, or grounds the junction of the signal diodes, keeping the FX signal from turning the effect loop on. The diodes form an AND-OR network, and let each programming switch be independent of all the others. Each switch turns on the +FX signal only if the LED is on and the +PG line for that switch is on. The latching is done at the footswitch, so you can have an indicator LED out at the footswitch, which can be in the same box, or can be on a remote cable. Not shown is an indicator LED per +PGx signal to indicate which program is active. With the latching and programming matrix setup, you can use CD4053 for a bypass, or buffer the +FX signal and use a relay, or use a pair of CMOS inverters to run a group of H11Fx photoFETs to switch each effects loop. The nice thing is that the diode isolation lets you make up a small switcher and grow it as you have the needs and money to do so. Once you pay for the jacks and 4053/relay/H11Fx bypass switches, you only have to add more programming switches and a footswitch per program you add. The footswitch setup goes to as many as eight programs.

12/16/1999 7:27 PM

R.G.

Re: The original thoughts

Ok, take a look at http://www.eden.com/~keen/fxselex.gif and http://www.eden.com/~keen/fxselex1.gif.

fxselex.gif shows the footswitch. You use a momentary footswitch per "program". That is cleaned up by a CMOS schmitt trigger gate and is latched by a 74C373. The six diodes work the enable/latch whenever any one of the footswitches is pressed (released, actually) and only one footswitch gets latched in. So we have a bit that says "Program active" for each footswitch. The circuit actually supports up to eight, but you want one for turning all the effects loops off and having a complete bypass.

fxselex1.gif shows the programming matrix. Each effects loop is controlled by a high level on +FXx_ON; the loop is bypassed when its +FX signal is low, and is enabled whenever its +FX signal is high. Each programming switch is one SPDT slide switch, three signal diodes and one LED/resistor as an indicator. The switch either grounds the LED, showing that the effects loop is active for that program, or grounds the junction of the signal diodes, keeping the FX signal from turning the effect loop on. The diodes form an AND-OR network, and let each programming switch be independent of all the others. Each switch turns on the +FX signal only if the LED is on and the +PG line for that switch is on.

The latching is done at the footswitch, so you can have an indicator LED out at the footswitch, which can be in the same box, or can be on a remote cable. Not shown is an indicator LED per +PGx signal to indicate which program is active.

With the latching and programming matrix setup, you can use CD4053 for a bypass, or buffer the +FX signal and use a relay, or use a pair of CMOS inverters to run a group of H11Fx photoFETs to switch each effects loop.

The nice thing is that the diode isolation lets you make up a small switcher and grow it as you have the needs and money to do so. Once you pay for the jacks and 4053/relay/H11Fx bypass switches, you only have to add more programming switches and a footswitch per program you add. The footswitch setup goes to as many as eight programs.

Replies:

Steve Newton A bit of latteral thinking on this subject -- 12/16/1999 9:12 PM
Jsh Using Midi cable as extention cord :-) -- 12/16/1999 9:20 PM
Joe Fuzz Re: The original thoughts -- 12/16/1999 11:17 PM