New Contender Power Supply for $300 Electronics Lab?

[Cliff Matthews]

At the ~$50 mark, the 2016 EEVblog #954 power supply option just got much better:

0-32v @ 5A, accurate metering (including watts), fan-less and compact, and more importantly, some pretty good specs. Max 8 mV ripple at any load and no significant peaks or on-off surges present at the output. As for the 2 x 470uF caps on the output (one on PCB and another at the panel), they could have done better but this was "built to a price" as Dave often says.

I would think forum members will find a quick mod to reduce ripple with less output capacitance. I would also like to think EEVblog members could convince Gophert to make some STM software mods before too long. Eg: Allow Watts display to stay on by default if user selects it.

[werediver]

Hey, this power supply looks pretty good to me. Some weak sides are the lack of PFC (if the VoltLog guy is right), lack of current fold-back mode, and 10 mVp-p noise (which is not bad, but could [always] be better).

I tried to find Gopher Technology site looking for the best way to buy such a power supply, but turns out their site is not operational anymore: gophertc.com The domain registration data suggests it for sale.

Does anybody know if the company is still alive?

And aside from that, maybe somebody could suggest a way to reduce the noise a bit further? (would a simple LC-filter be enough? ideally down to 1 mV)

Raman

[Cliff Matthews]

I fail to understand why having the added weight and complexity of PFC would be a deciding factor. An economy lab power supply is not typically used for long periods at high power levels..
BTW, since I posted this, the RD-6006 seems to offer a lot more for the money (best results IMO with linear back-end).
See main thread https://www.eevblog.com/forum/testgear/ruideng-riden-rd6006-dc-power-supply/

[werediver]

PCF is indeed of the least concern. I'm rather interested in recommendations on further ripple-and-noise filtering (but, well, I will just research LC-filters for noise reduction for starters) and, the most important, what's the preferred way to buy this power supply, which is closely connected to my question about their web-site.

But apparently, I failed to put the accents in the right way. Sorry about that.

[Cliff Matthews]

That is indeed the correct website address.. Page 5 of this manual says so. I checked also on https://www.isitdownrightnow.com/gophertc.com.html so maybe they've gone belly up? To bad, Riden needs competition.

[exe]

For some reason I thought PFC is required by law. Could someone clarify if this is the case? I'm interested to know about the situation in EU and US, and I'm curious about other countries too.

To give a bit more context: I've built a linear PSU made of a toroid tranny, bridge rectifier, big caps, etc. Obviously power factor is not great. I wonder if it is legal to use it.

[mikerj]

Hey, this power supply looks pretty good to me. Some weak sides are the lack of PFC (if the VoltLog guy is right), lack of current fold-back mode, and 10 mVp-p noise (which is not bad, but could [always] be better).

Fold back current limiting is something I would NOT want on a bench supply.  The ability to drive a constant current is extremely useful, and fold back limiting can create big problems with switch on current surges.

[werediver]

Fold back current limiting is something I would NOT want on a bench supply.  The ability to drive a constant current is extremely useful, and fold back limiting can create big problems with switch on current surges.

Sure it might be not suitable in some cases. I still think a fast fold-back current limiting as an option (imagine a switch "FB/CC") could be useful.

By the way, I got a reply to my e-mail to Gopher Technology. They confirmed they operate, but haven't commented on the site being unavailable. As for buying their product they suggest AliExpress.

[Cliff Matthews]

For some reason I thought PFC is required by law. Could someone clarify if this is the case? I'm interested to know about the situation in EU and US, and I'm curious about other countries too.

To give a bit more context: I've built a linear PSU made of a toroid tranny, bridge rectifier, big caps, etc. Obviously power factor is not great. I wonder if it is legal to use it.

If your nanny state can enter your home and take it away based on legality, I'd say they've gone way too far. Production and sales of certified products I can understand.. but hobbyist no. BTW, your toroid tranny gets better PF under higher loads, and under light load it doesn't amount to a hill of beans, so nothing to be concerned over. I'm not sure about countries, but here in Canada engineering firms can make some crazy custom products and easily receive certification stickers from the local province.

[wraper]

For some reason I thought PFC is required by law. Could someone clarify if this is the case? I'm interested to know about the situation in EU and US, and I'm curious about other countries too.

To give a bit more context: I've built a linear PSU made of a toroid tranny, bridge rectifier, big caps, etc. Obviously power factor is not great. I wonder if it is legal to use it.

PFC as such is not required. However there is requirement for harmonic distortion of the input current. For which PFC is basically the only reasonable solution.