Wow, now this has to be a mistake!!!

[Mikebits]

I been looking to get a new lab supply, and came across this on Ebay... This has to be a mistake, all I could say was holy cow...



Oh, and if anyone has a power supply recommendation, I would like to hear it. Dual output +/- ~20V 5A, not sure if linear is needed, I am doing some analog but I think the switch frequencies are well beyond the frequencies I would be working with. The specs I gave are just general, I am flexible on that.

 

[tcmtech]

I come across outrageously overpriced stuff like that all the time on eBay.

Personally I think that it's a way of doing money laundering in plain site.

I sell you an old power supply that' worth maybe $100 an a good day for $30K and you sell me an old car part that's worth maybe $100 for $30K a week later and boom! Now we both have semi legitimate covers for where that $30K we each made doing illegal things came from.

 

[alec_t]

I see two are available. Have you ordered both?

 

[JoeJester]

Deleted

on edit ...

Finally back on my computer and here is the **broken link removed**. It's a very good power supply.

What it's worth is what someone is willing to pay.

 

[kubeek]

Wow, those are some sweet specs! Not realy sure it´s worth the money compared to modern lab equipment, but sure that was an expensive unit back in its day.

 

[alec_t]

Just the job for powering/testing some little circuits designed around a 741 .

 

[kubeek]

Just the job for powering/testing some little circuits designed around a 741 .

I´d love to see how many of those beasts are actually used inside

 

[picbits]

Don't laugh - I opened a precision sensor power supply and found 8 x 741 opamps happily nesting away inside !

Even scarier was it was still putting out 10.001 volts on each output after 20 years in a harsh environment !

 

[cowboybob]

Don't laugh - I opened a precision sensor power supply and found 8 x 741 opamps happily nesting away inside !

Even scarier was it was still putting out 10.001 volts on each output after 20 years in a harsh environment !

AG ain't gonna be happy about that revelation. Especially you using the precision word....

 

[spec]

I been looking to get a new lab supply, and came across this on Ebay... This has to be a mistake, all I could say was holy cow...

View attachment 97862

Oh, and if anyone has a power supply recommendation, I would like to hear it. Dual output +/- ~20V 5A, not sure if linear is needed, I am doing some analog but I think the switch frequencies are well beyond the frequencies I would be working with. The specs I gave are just general, I am flexible on that.

I would stay away from that PSU if I were you- at that price they have obviously cut some corners

This is just a bit of cracker barrel advice but I think it is best to keep PSUs modular. So in your case I would suggest getting two separate PSUs. That gives you more flexibility, and also if you add a third PSU which is a typical set up: +15V,-15V for analogue supply rails and 1.8V or 2.2V, or 3.3V or 5V for logic rails.

The next decision is analog PSU or switcher. The Analogue PSU has the advantage of low noise and ripple (3mV) on the supply line, but is bigger and more expensive. The switcher on the other hand has more noise (100mV p/p) but is much smaller, lighter and is a bit cheaper. For general use analogue is best. A few members have been interested in PSUs and I did a survey and others contributed. What we came up with is a a pair of generic Ebay PSUs, one linear and one switch mode. Both have a voltage range of 0 to 30V and a current range of 0 to 10A.

The former is around $70 US and the later is around $60 US. When I was on the benches I had three 0 to 40V, 0 to 20A PSUs and they met practically all my PSU needs over a wide range of projects and over many years. Why 30V and why 10A? Firstly you can never have to many volts or too many amps, as long as they can be set. 30V is handy for audio power amp and 24V marine and truck work. You will also be pleased to have 10A available too, especially if you have some awkward circuit the takes large gulps of current, like an auto CD ignition system for example. In general it is not a good idea to run a PSU flat out either.

spec

https://www.electro-tech-online.com/threads/product-specs.146657/

Liner PSU
**broken link removed**

Switch mode PSU
**broken link removed**

 

[Mikebits]

Actually I was at a Keysight Test Drive event yesterday, and spoke with one of the account managers over there. I told him my needs based on some projects I am working on for use in industrial confined space instruments, and he is hooking me up with a Demo unit at about 50% original sale price. This is a very nice supply.

 

[spec]

Actually I was at a Keysight Test Drive event yesterday, and spoke with one of the account managers over there. I told him my needs based on some projects I am working on for use in industrial confined space instruments, and he is hooking me up with a Demo unit at about 50% original sale price. This is a very nice supply.

It does look nice. I particularly like the sense terminals on the front- you don't see those on cheap PSUs. It has also got an output voltage rail switch, which is handy. Is it linear or switch mode?

spec

 

[JimB]

A sweet looking power supply.
JimB

 

[Mikebits]

It does look nice. I particularly like the sense terminals on the front- you don't see those on cheap PSUs. It has also got an output voltage rail switch, which is handy. Is it linear or switch mode?

spec

It is linear. It weighs a lot. That was one of my first questions. In the proto type stage you want a very clean supply, so I learned at the test drive the linear is the way to go.

 

[Mikebits]

You should see the zone touch triggering on their scopes. This is such a nice feature, I hate my scope now

 

[spec]

It is linear. It weighs a lot. That was one of my first questions. In the proto type stage you want a very clean supply, so I learned at the test drive the linear is the way to go.

Being heavy, although sometimes inconvenient from a user POV, indicates a solid build, with non stressed components, especially the mains transformer. The PSUs I had at work weighed a ton and never missed a beat in around 20 years and they had some stick. Some of the lesser PSUs that the other guys chose didn't last that long. In general, switched mode PSUs are OK for digital work, but you really need linear for analogue. But having said that, good SMPs can have just as low noise and ripple as linear- my PSUs were SM but had very low noise and ripple- better than some linear types we had in the lab.

spec

 

[cowboybob]

You should see the zone touch triggering on their scopes. This is such a nice feature, I hate my scope now

Wow. That is a cool feature.

 

[throbscottle]

Remarkable exercise to try, random ebay searches and order the results "most expensive first".

 

[spec]

Remarkable exercise to try, random Ebay searches and order the results "most expensive first".

True but many PSUs, even when the prices vary quite a bit, are basically the same thing manufactured by a company in China

 

[throbscottle]

I meant random stuff, not specifically PSU's. Like this one for example - I searched for cd and listed most expensive first