Hello,
This is my first post in the forum.
I'm a hobbyist and I want to build a bench power supply, not necessarily from scratch. In fact I very much prefer to build it from power supply modules since it's much easier and also I think I already know how to do that.
I'm not sure about the requirements but I know that projects I'd wish to do include building circuits for power LED projects, testing brushless motors, and specially working with microcontrollers.
I researched a bit and read that for working with LEDs 60 volts and 6 amps is a good choice for the output, I'm not sure if it's correct but doesn't seem too far off because for example a 1 watt power LED has a voltage drop around 3v and maximum current of 300 mA so it's not hard to imagine chaining a couple of them in series would need that output.
I've also read that for embedded stuff usually a programmable power supply is needed which I'm not sure why, cause I only have experience with Arduino and its various modules so far, although I do plan to pivot my career in that direction.
So far I've read about the DPS5005 and ZK-4KX module but I think they aren't really suitable for my needs due to range and accuracy, although I'm on a very tight budget($60 more or less) and maybe should start with those.
If it's much cheaper to build it from scratch, I'm not really confident in my skills but I have some parts laying around like bridge rectifiers and voltage regulators and capacitors etc. which are needed for building a linear bench power supply from scratch.
So my questions are:
1. How accurate is the requirements I mentoined?
2. How realistic is to satisfy them within my specified budget?
3. Should I build from scratch or use modules?

 

Welcome to AAC!

I researched a bit and read that for working with LEDs 60 volts and 6 amps is a good choice

Building a 360W power supply isn't exactly a project for newbies.

although I'm on a very tight budget($60 more or less)

I bought a 30V/6A Wanptek switching supply from AliExpress for less than $50 (including shipping). I actually bought 3 of them from different sellers because they cost about half what I paid for a 30V/3A Velleman supply.

60V/5A will cost around $75.

 

360W of LEDs is about the same light output as 30 100W incandescent bulbs.

In 60 years doing electronics hobby projects I have never needed anywhere near that power.

 

It would be nice to get a general purpose laboratory bench power supply, but they cost money.
There was a recent discussion here:
https://forum.allaboutcircuits.com/threads/favorite-bench-supply.201916/

I will just repeat some of my thoughts here.

Instead of looking for a single adjustable PSU (it is worth saving your money for they day when that can become a reality), I would suggest looking at simpler and less costly solutions.

My #1 DIY PSU is a straight forward 5 VDC @ 1 A power supply. You will need the following:

Box
Power cord
Fuse
ON/OFF switch
Transformer
Bridge rectifier
Reservoir capacitor
LM7805 3-terminal regulator
Small capacitors
Banana jacks

This is the basic circuit:



For #2 PSU needs, visit second-hand stores and pick up inexpensive wall adapters of your choice.
I collect adapters such as 7.5 VDC @ 1000mA, 15 VDC @ 1000 mA, etc.
You can power a lot of hobby projects with these.

For #3 PSU options, shop around for old computer, gaming PSU.
You can find a single wall adapter that has ±15 VDC and +5 VDC outputs. Laptop power supplies often output 18 VDC @ 3A.

For #4 PSU options, an old PC PSU can supply +12 VDC and +5 VDC at a lot of amps.

For #5 PSU options, you can roll your own PSU to meet your desired needs with 3-terminal regulators, switching regulators, DC-to-DC buck and boost converters or modules.

Bottom line is, instead of a single supply, build simpler and inexpensive ones to fit your immediate needs.

 

It would be nice to get a general purpose laboratory bench power supply, but they cost money.
There was a recent discussion here:
https://forum.allaboutcircuits.com/threads/favorite-bench-supply.201916/

I will just repeat some of my thoughts here.

Instead of looking for a single adjustable PSU (it is worth saving your money for they day when that can become a reality), I would suggest looking at simpler and less costly solutions.

My #1 DIY PSU is a straight forward 5 VDC @ 1 A power supply. You will need the following:

Box
Power cord
Fuse
ON/OFF switch
Transformer
Bridge rectifier
Reservoir capacitor
LM7805 3-terminal regulator
Small capacitors
Banana jacks

This is the basic circuit:
View attachment 328621


For #2 PSU needs, visit second-hand stores and pick up inexpensive wall adapters of your choice.
I collect adapters such as 7.5 VDC @ 1000mA, 15 VDC @ 1000 mA, etc.
You can power a lot of hobby projects with these.

For #3 PSU options, shop around for old computer, gaming PSU.
You can find a single wall adapter that has ±15 VDC and +5 VDC outputs. Laptop power supplies often output 18 VDC @ 3A.

For #4 PSU options, an old PC PSU can supply +12 VDC and +5 VDC at a lot of amps.

For #5 PSU options, you can roll your own PSU to meet your desired needs with 3-terminal regulators, switching regulators, DC-to-DC buck and boost converters or modules.

Bottom line is, instead of a single supply, build simpler and inexpensive ones to fit your immediate needs.

Thank you, this actually sounds a much better solution than having a single power supply that is high-current and accurate and everythin. I don't have any old PSU though, so I think I might get one of those metal-case power supplies which have only a single voltage output but lots of current.

 

Hi,
first of all, I do not recommend to purchase a no-name PSU, even it is cheap.
I had a bad experience with a 50V 5A SMPS power supply and heard similar cases from other users

Second, if you want to work with LEDs, and you want to have 60V and 6A, I'd like to recommend you to find a used 48V/6A SMPS ( or two 24V/6A SMPSs ). And build 0-20V/0-6A linear Lab PSU.
You will have 68V/6A to experiment with the LED's.
It is not an insurmountable task to buid 20V/6A linear PSU. Take a 24V/6A transformer , those are widelly used, LM324' opamp and a couple 2N3055'.

 

Hi,
first of all, I do not recommend to purchase a no-name PSU, even it is cheap.
I had a bad experience with a 50V 5A SMPS power supply and heard similar cases from other users

That's actually what I was worried about so I was hesitant to buy one of those.

Second, if you want to work with LEDs, and you want to have 60V and 6A, I'd like to recommend you to find a used 48V/6A SMPS ( or two 24V/6A SMPSs ). And build 0-20V/0-6A linear Lab PSU.
You will have 68V/6A to experiment with the LED's.
It is not an insurmountable task to buid 20V/6A linear PSU. Take a 24V/6A transformer , those are widelly used, LM324' opamp and a couple 2N3055'.

So may I ask which one you recommend as a base? a transformer or SMPS? I've looked at the schematic for the linear one and it doesn't seem hard. My problem is to add features like protections and adjustable voltage and current limiting.
For the voltage adjustment I've read that it requires multiples taps on the transformer and then switching between them using relays but I'm not sure how complicated is to implement it.
For the current adjustment, although I have built simple adjustable current limiting circuits with LM317 chips, I assume building a proper circuit to put in bench power supply is more complicated than that.
And finally for the over voltage protection and such, I'm not sure even how they work and can't build them.
So this made me consider adding modules like DPS5005 and ZK-4KX to a metal-case SMPS but then I read people saying the modules are pretty inaccurate and have ripples and stuff specially under load but there's no exact numbers.

 

There is your basic PSU design and then there is a universal PSU with all the bells and whistles.

These are my basic needs in increasing order of desirable options:

1) Fixed voltage PSU, e.g. +5 VDC, 1A max
2) Variable voltage PSU, 0-15 VDC, or 0-25 VDC, 1 A max
3) Voltage readout
4) Current readout. Current limiting is a nice feature but rarely a necessity.
5) Fixed dual output, ±12 VDC or ±15 VDC, 100 mA max.
6) Bench PSU, 0-30 VDC, 5 A max. (In this case, current limiting is a useful feature when experimenting into unknown territory.)

As per (6), a general purpose laboratory bench PSU would have variable 0-30 VDC limit and 0-5 A limit, with both voltage and current readout. This is the one you want to save your money to buy.

(I hope that you understand that constant voltage (CV) and constant current (CC) are limits. If you don't, I can explain what I mean.)

 

That's actually what I was worried about so I was hesitant to buy one of those.

I suspect that a lot of power supplies are being manufactured China. Velleman isn't exactly an unknown name and their supply was probably made in China (a lot of stuff is, e.g. iPhone); with its dumb terminal order and non-standard spacing.

For the current adjustment, although I have built simple adjustable current limiting circuits with LM317 chips, I assume building a proper circuit to put in bench power supply is more complicated than that.

That won't work well for high currents.

Hiccup current limiting is easy to implement at any current.

 

Hello,
This is my first post in the forum.
I'm a hobbyist and I want to build a bench power supply, not necessarily from scratch. In fact I very much prefer to build it from power supply modules since it's much easier and also I think I already know how to do that.
I'm not sure about the requirements but I know that projects I'd wish to do include building circuits for power LED projects, testing brushless motors, and specially working with microcontrollers.
I researched a bit and read that for working with LEDs 60 volts and 6 amps is a good choice for the output, I'm not sure if it's correct but doesn't seem too far off because for example a 1 watt power LED has a voltage drop around 3v and maximum current of 300 mA so it's not hard to imagine chaining a couple of them in series would need that output.
I've also read that for embedded stuff usually a programmable power supply is needed which I'm not sure why, cause I only have experience with Arduino and its various modules so far, although I do plan to pivot my career in that direction.
So far I've read about the DPS5005 and ZK-4KX module but I think they aren't really suitable for my needs due to range and accuracy, although I'm on a very tight budget($60 more or less) and maybe should start with those.
If it's much cheaper to build it from scratch, I'm not really confident in my skills but I have some parts laying around like bridge rectifiers and voltage regulators and capacitors etc. which are needed for building a linear bench power supply from scratch.
So my questions are:
1. How accurate is the requirements I mentoined?
2. How realistic is to satisfy them within my specified budget?
3. Should I build from scratch or use modules?

Hi,

Not sure where you live, but you can get power supplies a lot cheaper these days that are already built and set to go.

In the USA you can get a 30 volt 5 amp power supply that has both voltage adjustment and current limit adjustment for around $50 or so USD. They are fairly small too now, about 7 x 3 x 5 inches with knobs on the front, current and voltage displays, and a USB 5v, 2 amp output as well. Hard to beat that.

A lot of linear supplies start with the ua723 voltage regulator IC chip that's been around for ages. Switchers are a little different. Then there are some switchers with linear backend that are efficient and have outputs that are close to pure linear.

 

I can suggest a rather cheap option, get a 12V 10A SMPS.
2) buck convertor : https://www.amazon.com/Converter-10-90V-1-5V-60V-Voltage-Regulator/dp/B0C84KBKG8
3) boost converter: https://www.hnhcart.com/products/150w-6a-dc-dc-step-up-boost-converter
4) V/I module: https://www.amazon.com/HiLetgo-Voltmeter-Ammeter-Digital-Meter/dp/B072BY4XZ7/ref=sr_1_5?sr=8-5
5) Multi turn potentiometer:

Want to know more about voltage current meters: https://www.hackster.io/sainisagar7294/diy-current-meter-using-arduino-60cc27
see this one also: https://www.hackster.io/LithiumION/variable-current-voltage-dc-power-supply-249a5e

 

That's actually what I was worried about so I was hesitant to buy one of those.



So may I ask which one you recommend as a base? a transformer or SMPS?

This is the transformer for a 380 watt supply. It is very large and heavy. I got this one on ebay for over 100 bucks but normally they are higher than that. Plus about 35 bucks for ground shipping.
Not shown are the required humongous heatsinks, even when using fans to cool them down. Another 100 bucks, easily.
Plus the “beer can” electrolytic caps and everything else.
High power linear supplies are absolute monsters.

 

This is the transformer for a 380 watt supply. It is very large and heavy. I got this one on ebay for over 100 bucks but normally they are higher than that. Plus about 35 bucks for ground shipping.
Not shown are the required humongous heatsinks, even when using fans to cool them down. Another 100 bucks, easily.
Plus the “beer can” electrolytic caps and everything else.
High power linear supplies are absolute monsters.

It looks really cool tho Made me wanna get something like that in the future when I'll have the skills to build something with it

 

I can suggest a rather cheap option, get a 12V 10A SMPS.

What is the minimum load requirement for that supply?

ak

 

That's actually what I was worried about so I was hesitant to buy one of those.



So may I ask which one you recommend as a base? a transformer or SMPS? I've looked at the schematic for the linear one and it doesn't seem hard. My problem is to add features like protections and adjustable voltage and current limiting.
For the voltage adjustment I've read that it requires multiples taps on the transformer and then switching between them using relays but I'm not sure how complicated is to implement it.
For the current adjustment, although I have built simple adjustable current limiting circuits with LM317 chips, I assume building a proper circuit to put in bench power supply is more complicated than that.
And finally for the over voltage protection and such, I'm not sure even how they work and can't build them.

A transformer one, they are called "linear laboratory power supply". I'd like to recommend you this:

https://www.friendlywire.com/articles/gear/ps303pro-schematic.pdf

The PSU can be simplified- the part built around the IC202 can be deleted, both relays RL1 and RL2 can be deleted too. Transformer data and ratings depends on the needed output. Two separate transformers can be used. First, big power transformer to power up B401, and second, small power to D101 and D102

 

Floating the regulator on top of the + output instead of it being referenced to the power GND - interesting approach. It gets around the emotional bias against putting the current measuring shunt in series the power return.

ak