#MEASURING OUTPUT VOLTAGE# Ideal laboratory power supply - YOURS requirements

[MacIntoshCZ]

I would be happy if you could give me your personal requirements for a laboratory source. All the features it should contain to make it interesting to you. Protection elements, voltage / current range,power output, accuracy, voltage ripple, efficiency etc ... I really appreciate the feedback =)
thanks

 

[rjenkinsgb]

OK!
I'd say 0 - 24V or higher, at least 5A and preferably more.

Setting and display for both voltage and current / current limit.

Output on.off switching while keeping voltage & current limit displays on.

Fixed voltage out for 3.3V and 5V logic at eg. 0.5 - 1A would be nice "bells and whistles" stuff.
Possibly even +/- 15 for analog?

Shutdown on signifiant or sustained overload - possibly switchable between fast and delay?
Instant shutdown if a logic supply output voltage increases, eg. due to a fault to a higher voltage output?

And appropriate fusing at input and outputs to minimise harm from catastrophic faults.

It's test gear so efficiency not too important as long as it does not get excessively hot in use.

Possible extra feature? A "maximum voltage select" switch, so if you are looking at a meter or scope whilst making adjustments, you can avoid accidentally over-voltaging things; eg. 5V, 12V, 15V, 24V or something like that.

 

[Nigel Goodwin]

OK!
I'd say 0 - 24V or higher, at least 5A and preferably more.

The thing is, how often do you use 5A? - nice idea, but it's probably only a very rarely used feature.

I've got a fairly nice Velleman one at home - it's two channel ,you can parallel or series them, or use them as a spilt supply - it's still in it's box

I unpacked it and made sure it worked, then put it back away - I've never used it yet.

At work I use one of the fairly small 'upright' ones - something like this:

Tenma 72-2700 Single Output DC Bench Power Supply, 60V, 3A : Amazon.co.uk: Business, Industry & Science

Tenma 72-2700 Single Output DC Bench Power Supply, 60V, 3A : Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

You can lock the output so you don't accidentally move it, and it's digital so it's easy to set the voltage and current accurately - it's used on a daily basis, and mostly multiple times.

I'm not sure of the exact specs. I'll look tomorrow.

But I would suggest you're better off with two smaller supplies rather than one large one - we've got three at work - two similar digital ones, and an older analogue one.

 

[MacIntoshCZ]

The thing is, how often do you use 5A? - nice idea, but it's probably only a very rarely used feature.

Personaly i have switching power supply capable of 0-50V 0-50A but is locked to 1kW. It was my first attempt and efficiency is something around 80% at full load. Thats horrible =D.
I am really into power electronics. Do you know any applications where such powerful power supplies are used?

 

[JimB]

I guess this guy did not understand the importance of ESD safe working areas.
Wrist straps, anti-static worktops and such like.

JimB

 

[schmitt trigger]

One thing is that it should have an output enable/disable capability, to adjust the voltage/current settings without having the load energized.

A “fine” adjustment capability is also very useful.

 

[MacIntoshCZ]

Also how much would you spend on PS? What about galvanic isolation thanks
At the moment i am thinking about llc topology, problem is voltage range. Those resonant topologies are best at fixed voltage output.
Two switchable windings at output. 230/25V/25V. With minimal gain 0.5 it could do range from 12V - 50V aprox.
Hard switched smps will be much easier... But i have possession in efficiency =). I am think in future efficiency will be "forgotten". Things should not get hot, but UNLIMITED POWER =)...

 

[Nigel Goodwin]

At work I use one of the fairly small 'upright' ones - something like this:

Tenma 72-2700 Single Output DC Bench Power Supply, 60V, 3A : Amazon.co.uk: Business, Industry & Science

Tenma 72-2700 Single Output DC Bench Power Supply, 60V, 3A : Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

You can lock the output so you don't accidentally move it, and it's digital so it's easy to set the voltage and current accurately - it's used on a daily basis, and mostly multiple times.

I'm not sure of the exact specs. I'll look tomorrow.

Only just remembered

My PSU at work is a Tenma (like in the link) but it's 30V 3A model is 72-2685.

It obviously uses relays to switch different windings, as you hear it click occasionally as you adjust it.

 

[Visitor]

For me, this kind of supply is hard to beat. I have the 6 amp version, but the latest is 18 amps.

These are actually buck controllers. You supply DC to it at up to 60 volts and 18 amps (in this case), perhaps with an open-frame supply, and this module regulates the voltage or current, with plenty of bells and whistles.

https://banggood.app.link/BveGUqc0Wdb

 

[MacIntoshCZ]

For me, this kind of supply is hard to beat. I have the 6 amp version, but the latest is 18 amps.

These are actually buck controllers. You supply DC to it at up to 60 volts and 18 amps (in this case), perhaps with an open-frame supply, and this module regulates the voltage or current, with plenty of bells and whistles.

https://banggood.app.link/BveGUqc0Wdb

Nice whats efficiency of this ps? Can it really source 1kW? Its relatively tiny.

 

[Visitor]

I have the 6 amp version and it seems to be an honest spec. They have an enclosure for it that holds an open-frame power supply and it has a fan for cooling, which is necessary at high loads.

 

[gophert]

I'd like a power supply that shows the set voltage and/or set current limit (depending on limit decision) and on a second row of displays, show the actual voltage and actual current draw - essentially a PS and meter in one.

I would also like to see a pair of "sense" thermals in case there is a voltage drop in the supply lines.

And added fixed supplies of 3.3 and 5v

 

[MacIntoshCZ]

Would you think hobbyist would rather have kit with SMD or THT parts? I would like to first aim on hobbyist. I never done smd but i know its critical if i wanna to move into production. So idea is to make two versions of PSU PCB ; THT for hobbyist / SMD for production. What do you think?

Also what about warranty when you are selling DIY kits? I think i saw on some eshop in CZ that they cannt give warranty cause you can screw it...

 

[Visitor]

Seems like with all the power supply options coming out of China, there's not much room for a low-volume variant. The Riden family of supplied that I mentioned above is very full-featured for the price. Smaller versions, like the one shown below, bring the same features at a lower price, and clones are available for half the price.

You might want to search "power supply module" on Banggood or ebay, and see what you're up against.

 

[MacIntoshCZ]

36V 5A eeeh, Mine would be 0- 50V 50A =) lowest variant

 

[gophert]

Have you thought about what kind of circuitboard will be needed to handle 50A?
and have you thought about what kind of hobby projects will need 2.5kW?

or, if someone expects a 50A load @ 3.3v - how much heat will your power supply have to dump to the outside world?

for the record, I have a 50v 1A supply that has ever been over 36v setting.

 

[MacIntoshCZ]

Have you thought about what kind of circuitboard will be needed to handle 50A?
and have you thought about what kind of hobby projects will need 2.5kW?

or, if someone expects a 50A load @ 3.3v - how much heat will your power supply have to dump to the outside world?

I am not making linear power supplies. This power is ability. It could be handy sometimes.
* Sorry it would not be 2,5kW. It will be 1kW fixed. 50A could be achieved up to 20V.

 

[gophert]

Linear or smps, at 85% efficacy on big drops, you'll still have significant heat generation, like the fan and heat sinks on a PC power supply - usually making much less power and waste heat.

 

[MacIntoshCZ]

Linear or smps, at 85% efficacy on big drops, you'll still have significant heat generation, like the fan and heat sinks on a PC power supply - usually making much less power and waste heat.

i am aiming to 95% efficiency at full load. I am using phase shift fullbridge topology with synchronous rectification, at low load i am switching from ccm do dcm. At very light load burst mode is used. I believe it would be ok. Also i want all parts below 60C degrees.

 

[gophert]

And the circuitboard that can handle 50A? I looked at making one recently and prices from a Chinese supplier in quantities of 1000 were in the range of $15 each.