With a new Quad Rev 2.72 I am getting VERY bad voltage accuracy – off by 10%-20%, even after calibration (not perfect calibration, I don’t have all the voltages – but close). It is reading off when the probes are grounded – something like 1V-2V on the 5v scale (others are similar). Playing with the calibration it seems like one will work and then others will not. Can’t try the community software due to 2.72. Could this be all in the factory firmware or is it common or is this a bad unit? What accuracy should I expect? I tried a DSO201 and it seemed much better in this respect.
Thanks!
There have been reports that the calibration software on the stock software with the 8M 2.72 model is problematic. I can’t say for certain as I have the 2M model. What I can say is that the base hw is OK from an accuracy point of view and after calibration gives decent results.
That, of course doesn’t help too much with the current inability to run much of the other software properly. Two things might be worth trying in the meantime. There appear to be later versions of the 8M App that may be worth trying. Also the gabonator APP is reported to be largely functional with 8M except when it comes to saving stuff to ‘disk’. You could try that at least to prove the calibration was OK.
hello i’m trying to calibrate my 2.72hw with gabonator app… 0,5V is no problem… but i cant set 1.5v corretly… the digits ends on 8 0 0 0 while i just have 1,378V …
any suggestions…
!
thanks
edit:
ok i found it… i had my probes on 10:1 … on 1:1 i can set the voltages…
but… if i try to control than the voltage with the adc settings, i have only on 0.5V the correct voltage on my multimeter… on 0.4v setting i’m on 0.127v … on 0.3V i’m on 2.52V , 0.6v are 0,88V , 0.7v are 1,26v… 0.8V are 1.65V … 0.9V are 2.04V on my multimeter…
something hast to be wrong…
i’ve just this guide:
i’ve managed it out now… calibrated the device with the gabonator firmware…
but if i use the wildcat firmware my display’d voltage isn’t correctly calibrated…
at the 10v setting CH-A tells me there is 5,2v and CH-B 3.2v …
it looks like the Vpos reset thing didn’t saved correctly…
or shouldn’t it? did i missed the thing the the dso can be calibratet with the gabonator firmware easily without an external power supply… is this calibration only available inside the gabonator firmware??
thx
Gabonator uses a different method of calibration using the internal DAC as the source. Other firmwares rely on you using an external voltage source which you vary to give an input voltage in the right range for each calibration point and then adjust the calibration to match the actual voltage fed in.
Similar story here.
It’s bizarre that you can’t put over 35v through it, but are required to calibrate to 50v. I’ve tried calibrating the voltage but leaving the last 2, but it’s still not right. I’m tempted to put 50v through it and unsolder the diodes if they blow.
The protection diodes on 2.72 will certainly blow with 50volts on the input.
It was a bad decision to add these and not thought through. There was a rumour they were going to remove them again as they add very little extra protection.
So you have a choice to remove them or remember to use x10 probes when using on signals which might go above 30v. You can calibrate using a lower voltage like 25v instead of 50v, just change the number to match the real input.
I didn’t think of that!
I should also add that having upgraded to the community firmware since making that post, calibration seems a lot better.