Designing a Pedal Power Regulator/Filter, powered by Laptop Power Supplies?

[Neil mcNasty]

For a while now I've been contemplating the idea of making a Power Regulator/Supply Box that is being fed by a standard Laptop Power Supply, but I never got around to making one, except for using such a power supply to power my Tiny Giant Amp, which trigger these thoughts in the first place.
What compels me about the idea, is the fact that these are capable of delivering up to 4-5 amps of power at 19.5 volts, so it should be possible (in my mind) to regulate this, so that it can put out both 9, 12 and 18 volts.
As far as I know; these already has a pretty decent power filtering in them, and should therefore be a good starting point.

It would be great to find a way to create a low cost alternative to the extremely expensive professional power supplies, that often lack both fuses that prevent you from overloading the regulators and proper power decoupling for the outputs.

My basic idea goes like this:
- Laptop Power Supply into a good polarity protection (transistor based instead of diodes?)
- Split it to 4 Voltage regulators (7809 type that can handle 1 amp) with 800mA fuses (to avoid overloading them and to have some headroom) for each of the regulators.
- Split each of the regulators to multiple outputs via Huminator style decoupling.
- One design that works well in a "reasonably" compact box that fits underneath your pedalboard.
- Have a main section that stays the same (Polarity Protection, 4 Regulators with fuses) and Breakout-boards with 8 DC-Jack outputs on each, so that it is scalable to handle big pedalboards.
- Make both a Veroboard version (for this site), and a PCB designs that can be sent to OSH Park (or similar) so that people can order professional PCBs + create a thorough Build Document with "etch your own" design that can be shared with the community.

In my mind it does not seem to be too complicated, and it would be great if it would be possible to nail it down to one single design that works well with these kind of power supplies, so that it becomes clear and easy for people to build it.
Too often I see forums that is loaded with an insane amount of variations of a circuit that confuses the hell out of me (not very often on this forum though, mostly on the other ones), and that is something that would be great to avoid. Therefore my wish to nail it down properly.

I know about many different power supply designs that can easily made, like Madbean's Road Rage and similar circuits.
But none of them are based on using a Laptop Power Supply or can offer all the features that I would like to see in such a build, + none of them has enough power to supply a large pedal board via one unit.
(my main board is quite big since it is being used for a lot of different styles and is used a lot for recording in the studio)

My wish is to be able to offer a solution that is not only cheaper than the professional ones, but also blows everything else off the map by implementing plenty of current so that you can have a shitload of outputs, with all the features that an "ultimate power supply" should offer.

So what do you think?
What are the "ultimate features", and what are the best ways to implement them?

All ideas and input are very welcome on the subject!

[Beaker]

Well I for one think that this is an awesome idea.

[Neil mcNasty]

After spending the day re-searching various polarity protection methods, I have come to the conclusion that using diodes is out of the question when dealing with high current draws, as these result in significant voltage drops and become very hot...
It seems that using a P-Channel Mosfet is the way to go.
But before getting the chance to test this method, I will need to order the correct type of Mosfet.

So far I have drawn up a circuit, and only need to implement the polarity protection before I start building and testing it.
In the meantime:
Here is a video that I found both very informative and amusing on the subject, that I suspect many will appreciate...

https://youtu.be/IrB-FPcv1Dc

Stay tuned for further developments...

[Ciaran Haslett]

Hi Neil

Don't know if you've seen this.  Plenty of options were built into it (not your protection scheme though)

[Neil mcNasty]

Yes Ciaran, I have seen and built it.
Works quite well.

But I want to avoid using a daisy chain in order to exploit the 1 amp current capability of the 7809's.
I would also like to avoid the 18v charge pump, as it only handles 100mA (which can be raised if using the 1054 instead, but still I would rather be without it)
The 78L09's are out of the question for the same reason + they fry easily...

Look at it, not as a power supply in itself...
But a kick-ass filtering, regulator and decoupling box for Laptop Power Supplies.
Exploiting a Laptop Power Supply is the starting point and at the heart of the project, as these are extremely compact, well regulated, and you can get these for free when your friend chucks his old laptop in the bin...

And I want something that has proper/better polarity protection at the input, has fuses to prevent the regulator from frying if you overload the outputs, steps the voltage down to 18v and 12v instead of up, with a decent current output so that it is capable of powering a DIY solid state amp, ala my modified Paul in Lab's 5 watt Sparky Amp (which I use at home and for traveling), and has a shitload of decoupled outputs for a HUGE pedal-board.