Those diodes are so robust that a PIC connected the wrong way to a 5V 1 Amp PSU was protected by all these diodes conducting in parallel and current limiting the PSU. The PIC appeared to have survived (although I chucked it anyway, just in case)
Andy www.g4jnt.com On Sat, 29 Jan 2022 at 18:56, Robert Atkinson via time-nuts < time-nuts@lists.febo.com> wrote: > You can run the PicDiv on 3.3 V and connect the 5V signal to the PicDiv > input via a series resistor between 1k and 10k. Put the resistor at the > PicDiv end of the connection. > The PIC has protection diodes on it's input These clamp the input to the > supply. The series resisor limits the current. This is robust. There are > thousands of devices out there with a pin conneted to the mains with just a > series resistor. t's used for zerocrossing detection or monitoring the > mains frequency. > Robert G8RPI. > > On Friday, 28 January 2022, 20:06:20 GMT, folkert < > folk...@vanheusden.com> wrote: > > Hi, > > I bought a GPSDO. It outputs somewhere around 3V. This is connected to a > picdiv and then to a raspberry pi. The picdiv is happy with 3.3v, the rpi > as well. All good. > > Now I bought a "Square Wave Amplifier" by BG7TBL ( > https://www.aliexpress.com/item/4000192799858.html?gatewayAdapt=glo2nld&spm=a2g0o.9042311.0.0.3d764c4dMZPAX8 > ). Documentation I could find was a bit vague about the > output voltage but I measured 5v with a scope (see > https://vanheusden.com/permshare/scope.png - the scope software says > 2MHz but output is really 10MHz). > > I did not study electronics, am only a electronics-hobbyist so bare with > me when this is a dumb question. > > The RPI doesn't like 5v on its GPIO pins. > So I wonder: > - can I feed the picdiv 5v on its GPIO pin while giving it a 3.3v > voltage so that it outputs 3.3v as well to the rpi pins? > - or should I use a voltage divider? I was thinking of a 4.7k ohm and > 8.2k ohm resistor giving slightly less than 3.2v - will that work? or > will that attenuate the signal too much? The 50 ohm bnc cable between > the amplifier and the rpi is 3m long. Anything else I should be aware > of? > > > Regards, > > Folkert van Heusden > PD9FVH > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send > an email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.