maybe a stupid question (brymen 867)

[dirk]

i'm new here and bought a Brymen 867 mainly based on this forum and a video review on youtube. It sure feels as a solid meter and I think it is a good upgrade from my fluke 75.

But now I have question. When I look at the dc volt setting I see the option when I press the select button to measure AC and DC on the dual screen at the same time. This doesn't make sense to me.

Can anyone enlighten me?

[tautech]

Welcome to the forum dirk.
I strongly suspect it is for measuring AC ripple on a DC supply.
Handy feature to see the expected DC level and the AC at the same time.
It would be handy for quick checks on PSU outputs to see if the smoothing caps are doing their job.

[dirk]

Thanks for the fast reply. I have a lot to learn!!!

[Lightages]

Yes, the option is to see DC only, DC with any AC voltage superimposed on the DC on the secondary display, or True-RMS with DC and see the AC component in the second display. These modes have different uses as Tautech says.

The DC mode with AC on the secondary can be used to measure ripple and noise within the bandwidth of the meter. It can also be used to trim the bias of the output of an amplifier so that there is no DC.

The True-RMS with DC can be used to troubleshoot problems where fuses or circuit breakers are blowing but you only think that there is AC present on the load but the DC offset is pushing much more power through the load.

These are just some simple examples of the use of these modes.