momentary electronic switching

[wcampagner]

Hello,

I'm using electronic switching in my stompboxes...
What i want to do now is to add another switch... so the stompbox will have two switches...

The first one would work like normal switch... if i step it will change the effect ONE/OFF.

The other switch would work as a momentary switch... that is: it is going to change the effect WHILE the switch is pressed...

So if i have to turn on the stompbox for around 2 seconds... i can step on the momentary switch and press for 2 seconds instead of turn the stompbox ON and OFF twice with the normal switch...

I want also that both switch work together... for example... if the stompbox is ON i want it to turn OFF while the momentary switch is pressed and if the stompbox is OFF i want it to turn ON while the momentary switch is pressed.

Do you get the idea?

I'm using the CD4013 Dual Flip-Flop for the electronic switching and also a pair of 2SK30A FTE's for the switching.

Did anybody have implement it? Or knows how to do it?

Thanks in advance,
Wagner.

[davebungo]

Basically, you need an exclusive OR (XOR) gate or function made from more primitive gates.  Feed your current latched signal into one input and your non-latched switch input into the other and bingo.

Logic: 0 = OFF, 1 = ON, A = latched signal, B = non-latched signal from second switch, Q = output to analogue switching circuit.

A  B  Q
=====
0  0  0
0  1  1
1  0  1
1  1  0

It would pay to have some de-bounce, but I guess you have already done this with your existing latching circuit.

[wcampagner]

Hello Davebungo,

Great idea!!!!! Very simple and efficient... i think this is going to work as i expect...

I didn't find any XOR CMOS gate so i'm thinking of using NAND and NOR gates (CD4001 and CD40011)...

Just a few things to point out: first of all i'll need another signal... the XOR signal INVERTED to control both FET's... i've made a drawing of how i think it will work (sorry for the bad quality, ok?)... what i call S is the XOR signal and S| is the XOR signal inverted...



Ok!! That's it... i think it will work using two IC's (both using all the 4 gates)... it was the best configuration i could find... it was better to use only one IC or none to save place on the box... but i don't think it is possible... if you lnow another way to do it using less components, please, let me know...  

The de-bouncing system will also be required because there is no way for it to work without de-bouncing...

Thanks a lot in advance,
Wagner

[wcampagner]

Hello again Davebungo,

I've searched the web and find XOR CMOS gates... both CD4030 and CD4070 are 4 XOR gates... so now the momentary circuit is using only one IC... one gate to mix the signals from latching and non-latching... and another XOR gate to make the INVERSE XOR signal... feed one XOR input with VCC and you'll get the INVERSE of what you put in the other input!!

Great... do you know the difference from CD4030 and CD4070??

Thanks again,
Wagner.

[DiyFreaque]

CD4030 is generally rated for lower Vcc than CD4070.

Cheers,
Scott