| Products > Test Equipment |
| Hacking the Siglent SDM3055 Bench DMM |
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| alexvg:
My Applent AT2816 is more precise for high value... But it's a specific device. I ve done 2 simple tests (with 2-wire and 4-wire) - a 110M resistance measurement with 4-wire display 111,7M to 112,5M over a minute - a 110M resistance measurement with 2-wire display 111,84M to 111,87M over a minute A funny thing I see each time... --- Code: ---=============================================== |SIGLENT SDG800 project /dev/pts/0 =============================================== SIGLENT Project http:// (none) (none) login: root Password: Processing /etc/profile... Done --- End code --- (SDG800 app and data are present inside the SDM3055 firmware) |
| alexvg:
I'm currently working on the frequency counter... It works up to 2,2MHz... Very limited ! My UNI-T181A (half the price) works up to 60MHz. Now I could use the frequency counter. I've measured a maximum frequency of : - 1Vpp : 3,1MHz square and 2,9MHz sine (Range 200mV) - 5Vpp : 4,1MHz square and 3,9MHz sine (Range 200mV) - 10Vpp : 5,0MHz square and 3,7MHz sine (Range 2V) - 20Vpp : 5,0MHz square and 5,0MHz sine (Range 2V) |
| alexvg:
Now I've got the Capacitance measurement process. It's possible to display a value with 5, 6, 7 or 8 digits... But the accuracy is very low... To check capacitors, I use a LCR Applent AT2816 at 100Hz / 2V I've done 34 measures with a list of 18 capacitors from 100pF to 10000uF. All capacitors have been checked before and after the measure of the SDM3055 with the LCR. Minimal error : 0,04% Maximal error : 10,2% Average error : 2,2% Std Deviation : 0,0228% The capacitance measurement of the SDM3055 is not very useful than a real LCR. I've also checked all capacitors using a low-cost LCR (Peaktech 2170). The results are always better than the SDM3055 ! |
| alexvg:
I've selected some components to build a pre-regulated power supply. - A couple of LM2991/LM2941 is used to create the +/-18V (regulated later for +/-15V) - A single BA80BC0WT is used to to create the +8V (regulated later for +5V) - A 100V/2A/0.7V Schottky bridge rectifier (+/-15V line) - A 40V/2A/0.5V Schottky bridge rectifier (+5V live) The main goal is to decrease the noise of these power lines and to reduce the heat of the main regulators. The selected LDO regulators have a switch pin which will be connected to the internal switch signal. I also need an additionnal power supply because I'll use a LTZ1000ACH instead of the MAX6325 for the ADC voltage reference. |
| CDaniel:
--- Quote from: alexvg on September 22, 2019, 06:33:09 pm ---Now I've got the Capacitance measurement process. It's possible to display a value with 5, 6, 7 or 8 digits... But the accuracy is very low... To check capacitors, I use a LCR Applent AT2816 at 100Hz / 2V I've done 34 measures with a list of 18 capacitors from 100pF to 10000uF. All capacitors have been checked before and after the measure of the SDM3055 with the LCR. Minimal error : 0,04% Maximal error : 10,2% Average error : 2,2% Std Deviation : 0,0228% The capacitance measurement of the SDM3055 is not very useful than a real LCR. I've also checked all capacitors using a low-cost LCR (Peaktech 2170). The results are always better than the SDM3055 ! --- End quote --- If the big error is for high value electrolytic caps it is fairly normal for a multimeter ... even two different Fluke don't display the same value and could be easily 10% off . For the simple method of charging/discharging the cap the time is dependent on losses and current used ... |
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