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| How to calibrate Siglent SPD1000X / SPD3303X / SPD3303X-E series power supplies? |
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| Bad_Driver:
The trigger problem is described in https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/msg3466342/#msg3466342 With the SDM3065 you easily see it with the scope connected to Trigger Out. Thats why I fiddled with external trigger etc. to get constant readings for FFT. I know that the audio check has very limited BW. For PSU measurement I built a Low Noise preamplifier ( 10 Hz…. 100 kHz) some weeks ago and with my 192 kHz, 24 bit semi professional external sound card and the software AudioTester you can do FFT up to 90 kHz. For higher frequencies -> SSA3021X/SVA1032X :-+ Unfortunately my design (2 stage OP amp for 60 dB) tends to oscillate and now I have a 3 stage design on the bench but not finished. |
| 2N3055:
--- Quote from: mawyatt on December 29, 2021, 02:48:04 pm ---Like 2N3055 mentioned, likely called a "Bootstrap Regulator or Reference". This has two stable voltage states, zero and the zener referenced, the 2 resistors and diode force the opamp into the desired zener state. The old 1N821 thru 1N829 series reference diode circuits used this technique as well. Best, --- End quote --- Absolutely correct, it probably originated with old ref zener diodes as a solution to run them at very specific zero tempco current, combined with hand picked good stability resistor.. But since even LM399 has some current dependency, it is used with LM399 too, to make it even more stable... Walt Jung used it to make his quiet linear regulators have excellent PSRR by virtue of feeding voltage reference with already regulated voltage... It's a gift that keeps on giving :-) |
| mawyatt:
--- Quote from: oz2cpu on December 29, 2021, 02:39:29 pm --- I have not seen this coupling before, dont you just love it, when something as normal as a teardown, ends with wisdom, --- End quote --- Very powerful learning experience, even for older folks :) Recall tearing down the HP3325 Function Generator when it first arrived way back, and curious how they achieved the ultra linear triangle waveform. They used a couple ECL gates and a fixed 100MHz (think it was 100) crystal oscillator for one gate input, the other input came from the frequency synthesizer which used the same 100MHz as a reference. The ECL gate output pulse width @ 100MHz varied as the frequency difference and was low pass filtered by a passive LC filter into an almost prefect triangle wave, which was amplified and offset scaled accordingly. Brilliant design concept!! Best, |
| Bad_Driver:
I wanna come back to our SDP3303X. I have to admit that it is not possible to get constant readings with the SDM3065, the time deviation between the readings during recording is very high - doesn't care if I use EasyDMM, USB-disk, internal recording which is missing a time stamp. Also external triggering doesn't help. Do the 3055 users have the same problem? Once again, Siglent, shame on you! So I used my 25y old 34401a, connected via Agilent GPIB-adaptor and the old but free software "Agilent DMM". I got very constant readings @ 16.5 Hz with 1 PLC and a far better FFT analysis of the SPD3303X output. Voltage = 1 volts since this fits best to the 1V range of the 34401a. FFT was done with EXCEL. Both devices are running for 24 hours. You see now much better the oscillating (yes, it is still in specs) of the output, I think it comes from a internal feedback loop of the regulator. I'm interested what you think? |
| oz2cpu:
is it recalculated to HZ the bins ? of the fft ? and YES i also belive it is regulation loop that is not performing uptimal, any one got a schematic ? come on siglent, we offer to fix this for you, for free, so this super nice supply, can be 10 times better performance :-) |
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