🚀 go-pugleaf

"LBNote" <lbonnell@ozemail.com.ua> wrote in message
news:4004a197$0$906$61c65585@uq-127creek-reader-02.brisbane.pipenetworks.com.au...
>
> "Ken Taylor" <ken123@xtra.co.nz> wrote in message
> news:bu26ge$co94h$1@ID-76636.news.uni-berlin.de...
> > "LBNote" <lbonnell@ozemail.com.ua> wrote in message
> >
>
news:400499cd$0$893$61c65585@uq-127creek-reader-02.brisbane.pipenetworks.com.au...
> > > Hi,
> > >
> > > Here is a basic description of the circuit,
> > > PIC16F628
> > > UHF Receiver Module @ ~433Mhz
> > > http://www.computronics.com.au/module/txrxpair/txrx_data.pdf
> > > 1 LED
> > > 1k Resister
> > > 5 Volt regulator, plus 22mf and 100nf caps
> > >
> > > I have the PIC simply blinking the LED ~ every 200ms
> > > and the UHF module data output connected to my scope
> > >
> > > What I notice is that the UHF data output swings along with the LED, I
> > mean
> > > instead of just showing normal garbage as is the case when no data is
> > being
> > > transmitted.
> > >
> > > Problem is NOT present when the LED is removed from the circuit
> > >
> > > The module still seems to recover data though.
> > > Can someone give me there thoughts on what's happening, I understand
> that
> > > something is causing interference,
> > >
> > > How can I stop this ?
> > >
> > >
> > > Lorne...
> > >
> > Do you have good supply bypassing on the PIC? Nice and close to the
> device?
> > Also for the module.
> >
> > Ken
> >
> >
> Thanks for your help Ken,
>
> On the UHF module I have a 2.2uf tant and a 100nf  close as I can,  but
> nothing on the PIC,
>
> Will give that a try tonight, will just the 100nf do or should I use the
2.2
> mf tant as well or other values I'm not sure, I don't even know what
science
> to use to find out the correct values.  I just borrowed those values from
> another (Similar ) circuit.
>
>
> Lorne...
>
It won't hurt anything to put both, particularly as you have UHF floating
around. The theory basically being that any capacitor will have a series
resonant frequency of its own, so having several in parallel makes it
unlikely that any one will matter. You could even put a 10pF in parallel
with them on the UHF module. I might even be tempted to put a slightly
larger tantalum in on the PIC, maybe 10uF, but it probably won't be critical
as I doubt if it is switching at a high rate internally. If you still have
trouble you could put in an RF choke on the supply to the UHF module.

Cheers.

Ken