HELP on step up sequential sw using cd4017

[bent]

i breadboard this http://members.shaw.ca/roma/e-switch.gif and did the errata to transfer the resistor and cap to the Base of transistor, but i'm using a bc549 and a 0.1 Uf cap + 1K,

the switching is working good, but sometime ( 1/6 ) it's step up 2 or 3 step on one push....

try to replace the 1K for 15K, very bad 
try to replace the 1K for 4k7 o, very bad 
try to replace the 1K for 470ohm, not good 
try to replace 0.1 uf with 0.47, not good 
try to replace 0.1 uf with 0.0022 not good 

any idea? or better schematic to suggest ?   
thank's

Bent

[arma61]

13   DIY Stompboxes / Building your own stompbox / Re: 3 instument switcher  on: March 10, 2009, 08:31:17 PM 
Hi

have a look at these,

http://www.diystompboxes.com/smfforum/index.php?topic=64228.0

http://www.diystompboxes.com/smfforum/index.php?topic=63536.msg512594#msg512594

it's a sequential switch for 3 FX + bypass, it pops a bit but the 3 fx are all high gain fx, and I never look this into deep.

It works fine, hit the button and it change from bypass to 1st fx then 2nd then 3d then bypass, no shot missing.

I've noted that the push button plays an important role when switching, so it has to be a "good one"

I have the schem+pcb layout in ExpressSCH and ExpressPCB if you need them.

Armando

[R.G.]

The circuits presented at that site seem appealing, but have been reported not to work very reliably.

What you're running into is that your switch has some bouncing and the transistor/resistor/cap is not debouncing it. The bounces get interpreted as additional switch closures by the logic circuit. Switch debouncing is one of those things that looks like it should be simple, but it's not.

Try this: resistor/cap to ground from pin 14. Cap = 0.1uF, resistor = 100K. Second resistor = 1K to first switch contact. Second switch contact to +V. When the switch contacts close, the first contact pulls up on the capacitor 100 times as fast as it can decay through the 100K. If the switch bounces, the cap merely stays where it was (mostly!) until the next bounce pulls it up again. The cap cannot sag between bounces, so the circuit thinks it stays "made". When the bouncing is over, the cap is pulled fully to +V by the switch and 1K. When you open the switch, it decays over a 50mS period because of the 100K resistor.

This circuit is not perfect, but it works pretty well in most situations.

[bent]

Try this: resistor/cap to ground from pin 14. Cap = 0.1uF, resistor = 100K. Second resistor = 1K to first switch contact. Second switch contact to +V.

Thank's R.G.,
Just try it, and it's not working....  , it's worst...switching fast, and step up 2-3  times....
i use those switch http://cgi.ebay.ca/3-Momentary-OFF-ON-FOR-FULLTONE-PEDAL-STOMP-SWITCH_W0QQitemZ290266051761QQihZ019QQcategoryZ50459QQcmdZViewItemQQ_trksidZp1742.m153.l1262?_trksid=p1742.m153.l1262

thank's 
bent

[bent]

anyone have another idea or another schematic ?

thank's

bent

[R.G.]

Yeah, but you won't like it.

Use the circuit I suggested but follow it with a schmitt trigger gate like a CD40106 or 74C14.

Debouncing is one of those things that seems like it should be simple but it's not.

Read here: http://www.ganssle.com/debouncing.pdf

It's the first result from putting "switch debouncing" into google.

[nelson]

Yeah, but you won't like it.

Use the circuit I suggested but follow it with a schmitt trigger gate like a CD40106 or 74C14.

Debouncing is one of those things that seems like it should be simple but it's not.

Read here: http://www.ganssle.com/debouncing.pdf

It's the first result from putting "switch debouncing" into google.

I thought 4017's already had schmidt triggers on the inputs?

(runs away)

[Nasse]

Yesterday, before falling to sleep, I read you can make sort of debouncing circuit from 4017. I think I buy few 4017´s next time I buy stuff...

[bent]

Well....i found a very satisfying solution....

i put a 0.047uF in parallel of the switch (v+ and base of bc549), it seem's to absorb the bounce, now it jump 1 step each time i press the switch, and every 1/15 it step 2, but then it's back for 1 step for a while...for me it's good enought..... 

i also try 1uFand 0.1uF, but nothing better...

thank's to all of you... 

bent