Getting electrocuted by cmos ics 4040 and 4016

Taller de Teknologia Libr · Joined: Jul 11, 2018 Posts: 4 Location: Chile

Hi , ive built a little synth based on a 40106 ic and a 4040 ic
The 40106 is providing the square wave , that im inputing on the 4040
then all the octave signals that i get from each pin , are going to a keyboard etched in a pcv.
So the ground is separated from the otuput signal, lately in this design im getting shortcuts when i touch de pads.
Can someone plis help me to why this hapens.Luckily the circuit is fed via a 9v batery but it still hurts when you play it.
There seems to be nothing wrong in the circuit.

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blue hell · Posted: Tue Feb 14, 2023 4:40 am Post subject:

Is the device connected to something else? like an amplifier maybe?

PHOBoS · Posted: Wed Feb 15, 2023 8:45 am Post subject:

Whatever is causing it is most likely what you have the output connected to, could be an amplifier as Jan mentioned.
Computers can also be a likely culprit. I have a similar problem here since I hardly have any sockets with an earth connection (only in the kitchen).

Computer PSU's can and most likely will have a filter in line with the mains supply but for it to work reliable it needs to be connected to mains
earth. Without it every ground connection could be connected to the mains supply through a couple of capacitors. This results in a voltage of half
the mains voltage between ground and earth. Since you are most likely connected to earth, unless you are some non-corporeal floating entity,
this can be noticable. Most of the time it will only make a metal surface feel somewhat rough as if it is coated in something, but if you have
a good connection with the earth it can be quite unpleasant.

I doubt that it could be directly lethal (maybe with certain heart conditions/pacemakers) but for devices where touching it is an important
feature, I would recommend to:
1. use batteries (as you already do)
2. use an audio transformer on the output and make sure there is no direct electrical connection between the output and the rest of the device.