The circuit is a bit small to see clearly, but as I understand, the need is to detect the presence of mains, and a measurement is not required?
If so, there are a few ways, such as using resistor and opto-coupler, electric field or transformer. There are also some ICs for this with built-in
isolation, but possibly not in a DIL-friendly package.
Some air gap is good. There used to be lots of high impedance volt detector circuits using JFETs (discrete JFET circuits are not as popular these days)
such as 2N3819/4416 I can try to dig some up if required.
Recently I needed to detect mains (well, actually to detect zero-crossing in my case) and I just used a small transformer, Farnell have some extremely
compact ones, I used one with 6V output which is 22x22x15mm and a comparator circuit. But then people need to lay out a PCB for mains, and
this starts getting difficult - see this discussion on mains control. But really if the OP just wants to detect mains, he could use any pre-built mains adapter
as gordon77 mentioned in that thread.
EDIT: Looks like Avago HCPL-3700 is available in DIL package. It needs series resistance for mains detection, but it has built-in isolation for the
remote side. The user still needs to lay out a PCB for mains though.
The circuit is a bit small to see clearly, but as I understand, the need is to detect the presence of mains, and a measurement is not required?
If so, there are a few ways, such as using resistor and opto-coupler, electric field or transformer. There are also some ICs for this with built-in
isolation, but possibly not in a DIL-friendly package.
Some air gap is good. There used to be lots of high impedance volt detector circuits using JFETs (discrete JFET circuits are not as popular these days)
such as 2N3819/4416 I can try to dig some up if required.
Recently I needed to detect mains (well, actually to detect zero-crossing in my case) and I just used a small transformer, Farnell have some extremely
compact ones, I used one with 6V output which is 22x22x15mm and a comparator circuit. But then people need to lay out a PCB for mains, and
this starts getting difficult - see this discussion on mains control. But really if the OP just wants to detect mains, he could use any pre-built mains adapter
as gordon77 mentioned in that thread.
EDIT: Looks like Avago HCPL-3700 is available in DIL package. It needs series resistance for mains detection, but it has built-in isolation for the
remote side. The user still needs to lay out a PCB for mains though.
