Hi
I have seen a number of people making differential probes for their 'scope for significantly cheaper than the purchased ones, for use with hobbyist level projects, including [this one][/https://xellers.wordpress.com/electronics/1ghz-active-differential-probe/] and [this one][/http://blog.weinigel.se/2016/02/26/ghz-differential-probe.html], and have decided I won't to make my own.
However, unlike these projects I was hoping that I could attached some standard passive probes to the thing instead of relying on the card-edge/bodge wire thing that these designs have used.
Additionally, I wanted something scaleable so that when I (hopefully soon) get a rigol ds1054z I can use it on all the channels.
I have thrown together the schematic/pcb ([available here][/https://www.dropbox.com/sh/v9gne9ihuqbs8h6/AACF3gfhZ-c7xxGUBDKdh7m6a?dl=0]), but to be honest, it ain't pretty.
Can anyone help me with getting this a bit more tidied up/organised/advice on component choice/overall design feasibility/etc?
It would only need to be usable for a couple of MHz.
Some thing that jump out at me are that the traces/layout between the channels aren't exactly the same - I couldn't find a way to do that in eagle.
Also, I couldn't hide some parts of the PSU from the schematic in the PCB (although I can understand why this would be a limitation, is there a way to mark these parts as 'not on this board' in eagle?)
I would be having the unit brought to mains-earth reference via the scope's ground terminals (to avoid ground loop issues), is this a bad idea?)
Are there different OP-amps that might fit this project a bit better (perhaps less bandwidth, but cheaper and in a larger package?).
Can I remove the input resistors and just rely on the probes input impedance (one of the designs from earlier noted that reducing their value could lead to some imporvement).
Is this even vaguely feasible for a hobby project?