Measurements Pura Dodo 5V
Contents
We do a few tests on power supplies these days. We want to know how quiet the power supply is, which we measure with a Tekbox RF current-probe as well as a direct measurement in the Prism dScope. Common mode and differential mode we measure with the spectral analyzer up to 1 MHz. That is more than enough for a power supply. We set the bandwidth resolution to 100 Hz, which is very accurate.
The loading of the power supply we do largely with an electronic load, because it has less influence on the measurement we have noticed. The Arcol variable resistor showed some influence in the pulse measurements (undershoot). The electronic load does not. However, for the noise measurement we do use the variable resistor, because the electronic load introduces noise. Not much, but too much to make good measurements.
Injecting the pulses, sines and square waves is done with a 60 MHz function generator connected to a class AB Bryston plate-amp. We obviously keep the signals very small, otherwise we may damage the power supplies.
Measurements load
Pay close attention to the names of the pictures: there are measurements without the power supply connected to show you the reference.
The Dodo shows that it is a fast power supply. The pulse is tracked nicely. The “undershoot” is the capacitor draining. That is normal. The square-wave test also shows how the capacitor is doing its job. (In the output is a capacitor with small capacitance (2200uF) to keep junk out. That cap charges with the signals we put in the power supply. And that is visible in this test.
We have also included measurements ‘without power supply’ for comparison. The stability of the power supply is neat. We loaded to 3A, but the power supply is specified at 2.5A. We see no excessive sag.
Noise measurements
Noise is undoubtedly very clean. We see almost no common-mode and also almost no differential mode noise. If we plug the Dodo directly into the Prism to measure low-frequency noise, we also see a tight line. For comparison, you see – in red – a very well known Sbooter 5V power supply. That one overtly shows 50 Hz harmonics in this test. The Dodo is dead quiet.
Quick and silent, this sound like Ferrum Hypsos! What’s the diff and which sounds better!?
Is there a Dodo with 1 output only 2?
I mentioned the Hypsos in the article. Both very nice PSU’s. I think the Dodo is even more silent. The Dodo only comes with two outputs.