60V/20A bench supply for $130? Bought and measured!

[mcdn]

There is a current control knob, so that does not work then?

It works fine, the Amazon reviewer probably got a different unit, see my post above. Into a short it does reset after a second or two, but no smoke or drama.

 

[mcdn]

https://www.electronicdesign.com/te...easuring-power-supply-transient-recovery-time

Ooh, handy, so we would use these as performance criteria?

My problem is going to be actually switching the load within those times. A physical switch will still be bouncing in the 2ms timeframe, as will a relay. 20A solid state relays look to be about $40 or more, which is more than I'd like to spend on an experiment. Ideas?

 

[Hayabusa]

Ooh, handy, so we would use these as performance criteria?

View attachment 410120
My problem is going to be actually switching the load within those times. A physical switch will still be bouncing in the 2ms timeframe, as will a relay. 20A solid state relays look to be about $40 or more, which is more than I'd like to spend on an experiment. Ideas?

may be use a amp module as load? You can feed that audio 'speed' loads to the power supply.

 

[mcdn]

@Hayabusa I just used a light switch in the end. Only measured at 19V/2A/180W so far as my PicoScope only goes to 20V and I can't be bothered to make a voltage divider yet. Trigger input at 0.0us. If there's a deviation it's maybe 150mV for 100us? That would put it almost in "high performance", and definitely at the good end of the "medium performance" ranking. Black Friday deals still available!

 

[mcdn]

I made a quick divider (4x10k resistors tapped between 3 and 4) and repeated the test at 30V and 60V into the same 2ohm load. Same story, the voltage doesn't really change at all when the load is connected. Eyeballing the picoscope trace, maybe it's +/- 150mV for 500uS? So medium performance on the scale you shared.

 

[AnalogSteph]

@AnalogSteph sure, you buy me the R&S scopes, I'll do the testing Seriously, my scopes are good enough for messing around but not at all useful when the noise levels are so low to begin with.

I dunno. I wouldn't be surprised to see a few volts CM. If it gets into sub-mV territory it isn't much to worry about anyway.

 

[SIY]

I have one of those, gift from @tubesguy. I did a little refurbishing and it works great.

 

[mhardy6647]

I have one of those, gift from @tubesguy. I did a little refurbishing and it works great.

I wish I had a high(er) voltage (400 VDC) Lambda supply.

 

[mcdn]

I dunno. I wouldn't be surprised to see a few volts CM. If it gets into sub-mV territory it isn't much to worry about anyway.

Here's the broadband noise up to 10MHz and then a zoom in to a few KHz. This is just AC coupling a probe to the positive terminal without connecting the ground lead to the negative terminal - I haven't built or bought a genuine CM separation device. Measurements are at 10V/50W. They tally well with an eyeball view of the raw scope data at around 10mV at various frequencies, so probably around 100mV total CM noise on a 10V output, for 1%.

For those following along, remember this is common mode noise so it doesn't affect the voltage difference between the output terminals, and therefore doesn't affect the stability of the power delivery. That number would be the ripple and differential noise, which as measured in the original post was much lower at around -80dB for 10V/50W