maxuino – problem with bouncing analog input

Mar 28, 2012 at 9:57pm

maxuino – problem with bouncing analog input

hi! i have a problem with simple patch, with even more simple schematics. it is voltage divider, and i cant get rid of bouncing values from analog input. i don't want to smooth it by software, because of my need to get data with good accuracy.

anyway, finally i want to make something like galvanic skin response reader, but for a group of people connected in series, to sense number of them. do you know any better way, to do this other than using voltage divider?

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#62650
Mar 29, 2012 at 7:42am

what kind of power supply are you using with the arduino? i had noise trouble because of a switching power supply. it’s better to get a regular one.

you’re problem might be something else though. the regularity in the oscillation is odd.

#226287
Mar 29, 2012 at 9:10am

There are debouncing chips like this:

http://uk.farnell.com/on-semiconductor/mc14490pg/ic-4000-cmos-4490-dip16-15v/dp/9664947?whydiditmatch=rel_3&matchedProduct=386595

But I’m not sure that is going to help you here.

#226288
Mar 29, 2012 at 1:03pm

thanks for answers.
dtr:
I have just tried with external power source – 9v batery, but nothing has changed. maybe the problem is in shared ground with usb interface?
Luke Woodbury:
good idea to use external ic, but unfortunately this chip is for hex operations, so it works only with binary numbers..

#226289
Mar 29, 2012 at 10:22pm

How about using a capacitor ?

Check this article : http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

#226290
Mar 31, 2012 at 3:47pm

i found that capasitor, works like slide object, and it doesnt works for my situation. i need accurate readings…

#226291
Jul 23, 2012 at 10:26pm

Cwiek:
“but unfortunately this chip is for hex operations, so it works only with binary numbers.. “

A hex contact debouncer means there a 6 contact debouncers in 1 IC package.
It has nothing to do with binary numbers.
In other words, you could use it to debounce the contacts of 6 switches or 6 relays.

Your issue has nothing to do with debouncing. I haven’t seen you mention any switches or contacts opening/closing.

Where is the signal coming from that you are looking at with an analog input?

I would try isolating that using an optoisolator..

You have power supply noise (aka ripple) or some kind of ground loop.

If you can avoid using the USB connection, try doing that.
Many PCs (even big name brands) use the cheapest, crappiest power supplies on the planet.

I recently measured 150mv p-p of noise coming from a brand new Acer computer.

A small capacitor between power & ground may help.

#226292
Jul 24, 2012 at 12:50am

finally i have used ADuM4160 + external 9v bat, and it works super great! thanks for help :)
adam

#226293

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