I've decided I'd have a go at making a small oscilloscope using a PIC microprocessor, a touch screen LCD and a couple of 8 bit ADC chips. I should be able to sample 2 channels at 8MHz, or 1 channel at 16MHz, which is plenty fast enough for what I normally need. It'll also have triggers and all of the normal stuff you would expect to have on a scope.
I've done previous projects with the LCD and touch screen and want to make my entire scope work with just the touch screen, but I'm a bit unsure as to how to switch the AC coupling capacitor in and out of circuit without using a physical switch. I could use a relay, but I'm trying to keep the PCB as small as possible (the same size as the LCD) and didn't really want to use a relay as the other components will all be SOIC chips and smaller. I was thinking of using small MOSFETs, but as AC signals are positive and negative, could I use 2 MOSFETs in parallel (drain to source, source to drain) to bypass the capacitor, or is there a better way?
Cheers for any help
Craig
I've done previous projects with the LCD and touch screen and want to make my entire scope work with just the touch screen, but I'm a bit unsure as to how to switch the AC coupling capacitor in and out of circuit without using a physical switch. I could use a relay, but I'm trying to keep the PCB as small as possible (the same size as the LCD) and didn't really want to use a relay as the other components will all be SOIC chips and smaller. I was thinking of using small MOSFETs, but as AC signals are positive and negative, could I use 2 MOSFETs in parallel (drain to source, source to drain) to bypass the capacitor, or is there a better way?
Cheers for any help
Craig