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| Siglent SPD3303D review |
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| willd1971:
If anyone's interested I have a couple of SPD3303C units in stock at Labtronix in the UK at £190ea. They are new stock so don't expect the CH3 problems described above. Here's the link: http://labtronix.co.uk/drupal/shop/powersupply/spd3303C |
| Murray:
Does anyone know what the output capacitance of this supply is? The Rigol DP832 has 1000uf directly across the output, which seems to me like it could defeat the usefulness of the current limit in some cases. The Korad programmable thing has 330uf. I was wondering what this one had. Thanks |
| FrankBuss:
--- Quote from: Murray on November 21, 2014, 03:34:58 pm ---Does anyone know what the output capacitance of this supply is? --- End quote --- That's an interesting question. I measured it: Test setup: Channel 1 on, current limit set to 10 mA with "fine" adjustment, voltage to 1 V. Then I connected a scope to a 10 ohm resistor and then the resistor leads to the power supply output while it was on. As you can see, it needs 2.3 ms to discharge to 37%, so with t=RC <=> C=t/R I think the output capacitor is 230 uF. But the interesting part is the 4.7 ms delay before we can see the current limitation. So I tested it with 100 ohm and 5 V output voltage: For 40 ms twice the selected output current is not good. This made me wonder what happens if you turn on the channel with load, when it should go to CC mode immediatly. New test setup: 10 ohm and scope connected to the channel 1 output, channel 1 is turned off, current limit set to 10 mA. Then I turn on channel 1: As you can see, it starts with 2 V, which means for the first millisecond there is a current of 200 mA instead of 10 mA. And after 10 ms the output voltage drops down to nearly 0 V, then rising again to the expected 0.1 V for the CC mode. Same problem for 100 mA current limit, it starts with 200 mA. But I guess no problem for most circuits, even a low current fast fuse would not blow in a millisecond. But it is worse with 1 ohm (screwed to the power supply output terminals) and 100 mA current limit, output voltage set to 10 V: Within the first few microseconds there is a peak of 3.2 A, the maximum output of the power supply, 32 times the selected limit. Again, it is too short to harm most DUTs, so I can live with that, but looks like there is room for improvement for Siglent how to implement the current limitation. |
| rf-loop:
--- Quote from: Murray on November 21, 2014, 03:34:58 pm ---Does anyone know what the output capacitance of this supply is? The Rigol DP832 has 1000uf directly across the output, which seems to me like it could defeat the usefulness of the current limit in some cases. The Korad programmable thing has 330uf. I was wondering what this one had. Thanks --- End quote --- Output capacitors are 220uF (+/- tolerances) Here also tiny test with SPD3303S for test it for load step response. Here Load change from 0.375A to 0.75A Step change in load using FET switcher (Switch FET is there IRF540N) unit controlled By Siglent SDG805 pulses and dummy load resistor set. (2kHz 170us pulses higher load) Switcth unit setup so that load rise and fall time roughly around 3-4us. (some amount softened switch so that dummy load resistors and wiring reactances do not produce ringing and disturb test.). CH4 is connected to switch D and S. Compared with equal test setup (including wiring) with Agilent 6632B what is 1x 0-20V 5A well known very good linear PSU. Agilent regulation set for FAST mode using switch in Agilent PSU rear panel. (as can see it is quite fast). Both was set for 7.5V and 3A limit so it means that both run full time in CV mode of course. Agilent have also sense lines. Connected just for "self happy" with jumpers between output terminal. Not sensed over real loa wires. But oscilloscope is connected to terminals, not after wiring to load. (same also with Siglent, measurement direectly from output binding posts and separate line to load. Of course Siglent loose this game but it was very clear before I get result. But Siglent result is not at all bad. It is also good to note that this Agilent list price strating from US$ 2,800) Images are self explanating. deleted (wrong information due to problem in this test demo unit.) I'm doing more many kind of tests but due to lack of time for this, I do these later. EDIT: This test totally obsolete. After tests it more I have found that this SPD3303S have problem. After then control board is changed as warranty issue. This case have delayed due to my own lack of time for this case. Later new tests. |
| rf-loop:
In meant time before more tests. SPD3303S Mains voltage 230Ac 6 hour: CH1 and CH2 total out 195W. Independent mode, both channels running in CV (constant voltage) to dummy load. ~31.22V and current ~3.122A) Room temp 22 celsius. No any signs of any kind of temperature problems. Also measured exhausted air temp. 41 - 42 celsius. 3 hour: CH1 and CH2 Independent mode. Both channels adjusted for 32V and 3.2A. Output terminals short circuited. Room temp 22-23 celsius. After 3 hour not any kind of signs about any kind of temperature problems. Exhausted air temp 40 - 41 celsius. |
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