Busardo interview is up on 50W. He has it at 3.86V and its doing PWM at 44hz, not 22K but very very little. Looks like at about 3.9 or 4V, it should be a flat line....a little wavvy, but flat. He talks about the rattlesnake sound often, but that has never been my issue, just the taste factor of PWM, when it fires too hot.
The next step up to a DNA 40 or SX Mini with with true step down buck boost is about 4 times the price. I hear some think specific clones have boost buck step down.....but would never be sure unless its benched.
I could live with a SVD 2.0 in a smaller than MVP 3 form factor
Must admit I'm not bothered by PWM - as long as it's set with RMS calcs. Since the istick 50W uses RMS, that's fine for me. Mostly though, I'm using it with coils I built for mechs, setting it around 4V, and enjoying the DC with no fade
The 22k I saw was the operating frequency of the DC-DC converter of the istick 30W, at 3V, with about 1.2 ohms. As I noted in a later post, when the 30W uses PWM it is low speed.
The interesting question is when the 50W switches from PWM to DC. Did pbusardo say what ohms he was using for those scope traces? I didn't catch it. (I know he was using various ohms for the voltage and power accuracy tests, but looks like only one when he showed the PWM and DC traces).
My theory is that the DC-DC converter they have
can buck, but is only able to do it within a certain range of current outputs. When the current demand is lower, it seems it can do DC to a lower voltage. That explains the difference on the german video between 0.4 and 1.9 ohm coils (and also the ripply output I saw on the 30W, right at the edge of its DC area). So there isn't a single voltage where it changes from PWM to DC, possibly many, and it isn't quite as simple as boost=DC, buck=PWM.
