Hobbyist small power supply

[alifred]

I'm currently deciding on my 3rd year individual project for my Electronic Engineering masters in the UK. I want to design and make a small hobbyist bench power supply, but not like standard ones.

I was thinking along the lines of:
- Very small desk footprint
- Powered from laptop power brick
- Single output with CV and CC
- 0-12V at 0-2A or so
- Switching pre-reg and 'classical' analogue front end
- Small screen (possibly OLED) and rotary encoders for V-set and I-set
- Ability to stack units together to more outputs (and split supply)
- Be very cheap for hobbyist/educational use

What do people think about this style of PSU? I would happily take peoples suggestions as to features to include and the sort of target market/target price you think I should try to hit.

Thanks for your suggestions in advance
Freddie

 

[manoj soorya]

Hi

Good Projects for Hobbyest too...You can use with LM723 SMD regulator....Its can V Adj and I Adj...

You can also use analog Vu meter for Indicating Vthe OutPut Voltage and Current....

God Bless You

 

[crutschow]

Good Projects for Hobbyest too...You can use with LM723 SMD regulator....Its can V Adj and I Adj...
....................

The LM723 does not readily adjust to 0V output so that's not a good choice.

 

[JimB]

JimB comments in Red

I was thinking along the lines of:
- Very small desk footprint But not once the laptop brick and its cables are taken into account.
- Powered from laptop power brick OK, but if the user only has one laptop and wants to use it at the same time as the PSU?
Also, consider the variation in types of laptop power connectors.
- Single output with CV and CC OK
- 0-12V at 0-2A or so OK
- Switching pre-reg and 'classical' analogue front end Two stages of regulation seems to add complication and cost
- Small screen (possibly OLED) and rotary encoders for V-set and I-set Novel, interesting
- Ability to stack units together to more outputs (and split supply) If the individual supplies are to be indepandant, to give say +/- 12volts, you will need isolation from the the common supply from the brick.
- Be very cheap for hobbyist/educational use Define "very cheap"

JimB

 

[alifred]

You could still make it a lot smaller than traditional bench power supply even with a laptop brick incorporated. That would also negate having to support different plug types from different PSUs.
I feel two stage rectification necessary as to not burn excessive amounts of power and give a large (ish) output voltage range with a fixed input.
Hmm, I was thinking of using one brick per supply, but are the laptop bricks mains earth referenced?
I was thinking of making it in the ~£50 category. What price point would you suggest?

 

[ronv]

Take a look at this one. There used to be a link to it here but I think it crashed.
https://forum.allaboutcircuits.com/threads/power-supply.89468/#post-648342

PS. Post #4

 

[Joe G]

I made one to replace my 1st homemade one. I also used a laptop psu, I used 317 regulators set for a max of 14.7V and 1.5A max. I put a smps chip for a steady 5 and 3.3 volt outputs besides the variable V/C op,. I used a INA226 for the voltage and currant monitoring fed to duel 7seg displays. Also I added a comparator to monitor a thermistor for any overheating and turn on a cooling fan.

 

[KeepItSimpleStupid]

This https://www.google.com/url?sa=t&rct...7u2bvlRO8nO-YsQikc4LQ&bvm=bv.76943099,d.cWcis always a good read just to understand power supplies in general.

Many manufactures make power supplies that can be placed in series or parallel and generally operated by one control. What I haven't seen is a "tracking" modular supply. Heathkit made an interesting power supply at one time. +5 and +- (0-15 V) at about 0.5 A. It had an analog meter that could measure I or V.
It had ersatz tracking - meaning a dual pot controlled the independent power supplies.

Some supplies have a "shutdown" method which can turn off a power supply. Some of the supplies I used had a 0-5 V output for both voltage and current, Many early designs did not isolate these outputs. The problem is that the external setpoint is usually referenced to the positive terminal and so is one of the current measuring legs.

You don't appear to be at the current that would require sense leads, but if your doing series and parallel operation, you may need them.

 

[alifred]

This https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCAQFjAA&url=https://literature.cdn.keysight.com/litweb/pdf/5952-4020.pdf&ei=vykzVO6tOPCAsQTSoYLoBw&usg=AFQjCNGBYLS4VXaWx4EWZriXcvO4oiF6wA&sig2=B7u2bvlRO8nO-YsQikc4LQ&bvm=bv.76943099,d.cWcis always a good read just to understand power supplies in general.

Ah awesome, thanks for that!