I will try a HV test, but I have to rig something up for that - do not have any HV testing gear of my own other then a Fluke HV probe.
USB ISOLATOR SERIAL
I am sure it will work perfectly with any USB to serial device like Arduino boards. The USB scope noise seemed to be about half what is was when connected to the PC directly. Even the scope had a very good update rate on the screen - hardly noticed a difference. Tried it with a Hantek DSO-2150 USB scope and a Logicport USB Logic analyser and both worked flawlessly. Anyway, it is only USB 2.0 High Full Speed (12mBits/sec) so I wasn't sure how it would work. It will probably rise to about 12pF to 14pF when powered, but it was a bit hard to measure.
The unpowered capacitance across the gap was 4pF. Without the DC-DC isolator, the only things spanning the insulation gap are an Everlight EV817 opticoupler rated at 5000V RMS and an Analog Devices UDuM3160 USM isolator chip rated at 2500V RMS for 1 minute (UL). Removing the DC-DC isolator means you do need a powered USB hub on the unpowered side of the isolator. I will file the board and pads where the isolator was located away to make a proper gap. It is only 200mA out, it says it is not properly regulated in the data sheet and it is rated only up to 1000V. I pulled the isolated DC 5V-5V isolator off. A search for USB to USB isolator will find them. The problem is in both directions - noise from the PC going to the device been tested, and the risk that if the test generates a massive spike, my desktop PC may be damaged. The motivation is that I have always been uncomfortable about testing stuff on the bench while I have equipment directly attached to the device under test plugging directly into my desktop's PC's electronics via a USB cable. Just got my A$15 usb to usb isolators, and they are brilliant.
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