Power supply regulation problems with USB Isolator and external power supply?

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Bitsplitter
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Joined: Tue Mar 28, 2023 10:21 pm

Power supply regulation problems with USB Isolator and external power supply?

Post by Bitsplitter »

I have a 2204A that I want to connect via an USB Isolator to a notebook, that I can measure 230VAC signals without being electrocuted, typing on the keyboard and touching the notebook's metal case.

The USB Isolator (Exsys 1451) works with other devices with external power supply.
But with the 2204A at setting up/connecting the device, I hear the relays working inside the 2204A, but no connection happens.

How does the power supply current jumps during device detection/initialization/connection?
I cannot measure the current - it is the only DSO I have.

I assume that the power supply (5 V 2 A, delivering 5.33V without load) has a bad load regulation?
If you send me a typical current-time graph I can check the power supply for that load changes.
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Gerry
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Joined: Mon Aug 11, 2014 11:14 am

Re: Power supply regulation problems with USB Isolator and external power supply?

Post by Gerry »

Hi Bitsplitter,

Bitsplitter wrote: ↑
Mon Jan 08, 2024 10:18 pm
 that I can measure 230VAC signals without being electrocuted
Well, unfortunately, you're approaching this the wrong way. Even if you got the isolator working you run the risk of damaging your Scope. What you should be doing is using Voltage Probes that are suitable for measuring potentially hazardous voltages, such as the High Voltage Differential Probe here: https://www.picotech.com/accessories/ac ... tial-probe , as 230V AC is actually 230V[rms] which is 650V pk-pk But, more importantly, this is also a whole lot of current that your PicoScope setup may not be able to protect you from.

Regards,

Gerry
Gerry
Technical Specialist
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