Measure 1000 volts with my Rigol DS1104z - Page 1
Forum section: electronics / testgear

author: manytoolsmike
author_rank: Contributor
timestamp: March 30, 2021, 03:19:13 am
content: Hey guys,Im probing the output of an Ultrasonic driver. The signal maxes out my scope with the 10x probes. It is less than 500 Vac (1000 peak to peak), the frequency is 10 kHz to 80 kHz.Should I go with a x20 Passive probe? It seems that will get me there. I also want to measure the current on the same signal, so a recommendation for a suitable current probe would also be appreciated.I am experienced with High voltage and frequency. I understand the dangers.Thank you for your helpMike.

author: tautech
author_rank: Super Contributor
timestamp: March 30, 2021, 03:25:57 am
content: Quote from: manytoolsmike on March 30, 2021, 03:19:13 amObviously not !Use 100:1 probe at the minimum or preferably a 1000:1

author: Kean
author_rank: Unknown
timestamp: March 30, 2021, 03:33:56 am
content: Very likely the peak voltages are higher. Ask me how I know...I'd suggest you use a Micsig differential probe and matching current clamp. A bit expensive, but way way safer for you and your equipment.Look at the DP20003 as the max voltage on the DP10013 is a little too close to what you'll probably be measuring. For the current clamp the Micsig CP2100A or CP2100B (sold by Dave) is a very good option.

author: bdunham7
author_rank: Super Contributor
timestamp: March 30, 2021, 03:48:48 am
content: The problem is that at that voltage and frequency, you will have to look closely at the frequency derating curve of the probe. Many 100X probes won't be sufficient at that level. I imagine the power level must be quite high, but at 80kHz, your probes actual input impedance will only be a small fraction of its nominal value, so circuit loading is still a possible issue.As for the current, the old Tek AM503 or AM503 amplifier with the A6302 probe would be nice.

author: tautech
author_rank: Super Contributor
timestamp: March 30, 2021, 04:36:40 am
content: Quote from: bdunham7 on March 30, 2021, 03:48:48 amThis is where a 1000:1 probe is often much better offering just a few pF's tip capacitance which is almost down at active probe levels.

author: manytoolsmike
author_rank: Contributor
timestamp: March 30, 2021, 05:11:05 am
content: Thank you all for your help. This is the greatest forum. I'll look for a good 100x probe and check out the current probes you listed.As one reply mentioned, this is a relatively high power system. It is around 6 Watts power to the H-bridge @ 28 kHz. Then there is a transformer bumping the voltage up to 400 V. I am concerned the peaks will be more than I am expecting, but I'll try the 100x first.The system pulses 300 ms bursts in a 5 second cycle through a range of several frequencies (8 kHz to 80 kHz) I am having to really learn my scope! This is the most difficult wave form I've tried to capture. I see lots of messy wave forms and ringing.Mike.

author: Fungus
author_rank: Super Contributor
timestamp: March 30, 2021, 10:12:10 am
content: Quote from: manytoolsmike on March 30, 2021, 03:19:13 amYour 'scope can easily measure half a volt so why not go for a bit extra, just to be sure?eg. 100x, or even 1000x.