Firstly, if you are having issues with power then generally the best way is
to add more capacitors in the areas where the power is being used. So in
this case ideally you would have a 0.1uF and possibly a 1-2.2uF near each
connector.
The second, is that you’re putting power over jack plugs, you’ll find that
the plug may potentially short pins together during insertion/removal. I
would recommend that any power to these is connected through a resistor, or
say 100R or so that any shorts are limited in the power they can draw.
I am not sure if you really need debouncing on an analogue input, a
pontentiometer should do a smooth progression from one state to the other.
You may want to do a bit of noise filtering if the cabling is picking up
noise, but a small capacitor (of around 1nF) should be capable of removing
some of that. You’ll not get rid of all the noise as the A-D process is
also going to be noisy.
As for the A-D, you may want to reduce the resitance of your pots, or use a
buffer op-amp as the AD on the AT chips can present anywhere between 1-100K
load when sampling pins.
TBH, you need to tidy those schematics up. For example:
- Use right-angles for wires only
- No upside down test
- Try to avoid lots of wires joining at once
- Clear join points where wires join (avoid ambiguity where wires cross)On 24 April 2014 13:29, Constantin Popp constantin.popp@gmail.com wrote:
hi all,
could anybody help me with this circuit?
https://lh3.googleusercontent.com/-g74AaV9tuRU/U1j-zJGCewI/AAAAAAAAAao/mbAXsUfFbzo/s1600/p2o+new+03_pcb.png
https://lh3.googleusercontent.com/-g74AaV9tuRU/U1j-zJGCewI/AAAAAAAAAao/mbAXsUfFbzo/s1600/p2o+new+03_pcb.png
https://lh4.googleusercontent.com/-Lw2L-PiyCMU/U1kDJ4wDrOI/AAAAAAAAAa8/3sNtKSRG7Yw/s1600/p2o+new+03_schem.png
the question i have is related to the de-bouncing and smoothing. at the
bottom of the circuits 4 stereo jack connectors are found. the first two
will have potentiometers connected to them. the wiper will be attached to
the tip pin of the jack. i would like to reduce possible noise from this
end. so i put a capacitor of 0.1 uF between the analog pin and ground. will
this work? the question arises with regard to the de-bouncing i’ve used
with the switches, connected to the jack connectors 3 and 4. here, the
schematics i’ve found in the net asked for a resistor/capacitor combination
to simulate a simple low-pass filter. wouldn’t this be the same thing as
with the connector 1/2. or in other words: are the connectors 1/2 also
missing a resistor each or could i skip the resistors for the connectors
3/4?
is the 10kOhm for the resistor and 0.1 uF for the cap correct to induce a
lag of 0.1 seconds.
another question is related to the stability of the power i’m feeding to
the connectors. in one posting i found that a 47 uF cap wired across
ground/+5v should reduce noise best. in the moment, i think, i have wired
only a 0.1 uF capacitor. this one is supposed to avoid spikes in the power
if someone (un)-plugs something from the connectors. should i increase this
capacitor here to reduce the noise more? if so to which value?
also, not sure if the schematics are drawn correctly. i think the pcb
wiring should be more accurate.
thanks a million for the help!
cheers,
const
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