Need help with a sequential switch with 4017&4066, plse help!!

[arma61]

Hi

I've got this 2 schems

http://hammer.ampage.org/files/quadsequentialswitch.pdf

http://members.shaw.ca/roma/switching-2.html (there are some pins connections error in this schem, but the idea seems to be ok)
(thanks to markH and laurier!)


I'm building a sequential switch for my 3Distorsors box as I want only one dist. on at a time, with above suggestion I've drawn this schem



I've build the pcb and tested it, the first part with 4017 is working fine the 4 LEDs are on sequentially pushing the switch
The second part has problem, testing the circuit with an audio probe I've the signal on pins 2,10,3,9 all the time regardless wich LED is on, but the signal corresponding to the LED on is strongest than
on the other pins.

Is there anybody expert in this to check this circuit for error?

Thx vvvvvvvvvm
Ciao
Armando

[pjwhite]

What voltage level is your input signal?  The 4066 can handle signals between VSS and VDD (A+ and GND).  If your input has a negative voltage swing, that could be causing your problem.  Try AC coupling the input with a capacitor and a resistor bias network to put the idle input voltage at A+ / 2.

Also, the transistor in your switching circuit is redundant and could be eliminated.

[The Tone God]

Your LEDs might be pulling too much from the line to switch the 4066s. You might want to check out the Vanishing Point v1.0 for ideas like using driver transistors for the LEDs.

Andrew

[arma61]

Thx pjwhite, the signal is a guitar signal, so voltage should be 0, isn't it?

Thx TTG, I had a look at your Vanishing Point and modded the schem like this



is this what you mean?


lads how hard is building something starting from the project itself!! I used to take what´s "ready made" here in the forum, but this time I want to do something myself, but my knowledge/skill of this stuff is realy close to zero. So thanks a lot for helping me guys.


Ciao
Armando

[The Tone God]

Yep but I would still add those 10Ks on the base of the LED transistors.

Andrew

[arma61]

ok, breadbording just now with new schem and added the 10ks on the base of the LED transistors  , it's improving a lot, still there some IN signal on the "not shunted" pins, I mean I'm connecting input signal (from a small radio) to pins 1,11,4,8 and clock signal to pin 13 (shunts 1 with 2), so on pin 2 I have the signal like on pin 1 and this is good, then if I connect the audio probe to pins 10,3,9 I can still hear the input signal very very low.

I'll try also to reduce clock voltage with a resistor network to 4.5V

thx
Armando

[pjwhite]

What effects are you using for the three places shown on the schematic?  It's possible that you are getting leakage here from the effects outputs back to the inputs, especially if any of the effects are in bypass mode.

[arma61]

they are an AMZ OD PRO a Guv'nor and a BigMuffPi, but at the moment they are not connected, I just use an FM radio's signal to test connections

[pjwhite]

Try putting a 10K resistor to ground on each of the three 4066 outputs that would normally go to the effect inputs (pins 10, 3 and 9). 

And I still think that biasing the input to A+/2 would be a good idea.  Something like this:

[arma61]

thx pjwhite, I'll try with those 10k to 4066 outputs, but I dont get the second schem, do you mean I need to feed A+ to the guitar signal? , I'll do that but I would like to understand that!

[pjwhite]

The two resistors form a voltage divider that put a DC bias on the input signal, making it well within the operational range of the 4066 switches.  Let's say that A+ is 9 volts.  The inputs to the 4066 will now be the AC input signal (some millivolts) plus 4.5 volts.  The input signal can now swing negative or positive and still be between 0 volts and 9 volts, the power supply rails of the 4066.

[arma61]

you're awesome pjwhite!, it works now, it seems I have signal only on the "on" pin, the other pins seem quiet, it's still on a breadboard so a lot of noise, hum, motorboat, and even whistle. I'll make a pcb soon and test it on the real thing, it will be my PJSS pjwhite Sequential Switcher!! (ehi! nice I like this name pjss !!!)

Thx a lot to everybody.
Armando

[arma61]

Hi all, so at the end I get it working, thank also to this post http://www.diystompboxes.com/smfforum/index.php?topic=64228.0 and thx again to pjwhite.
BTW I really named it PJSS Sequential Switch :




and thx to John Lyons too for etching and drilling the board!

Ciao
Armando

[Paul Perry (Frostwave)]

An interesting extension of this, would be a switched mixer.
Imagine a simple three channel mixer, blending inputs from the distortion units, all being on at the same time.

Now imagine having copying the mixer stage several times - so you have a choice of mixed outputs.
And use the PJSS to select which premixed blend you wanted.

True, it would get large & expensive as the knobs added up - but if you are OK with using trimpots & not resetting it between gigs, it would be OK.