Earth grounding enclosure

[liquidgunsmoke]

Hey all,

So after poking around the internet for a few days, I have a quick question regarding grounding that I have not been able to find a definitive answer for and am thus turning to the community.

I'm building a Colorsound Supa Sustain clone. This box requires 18V PS instead of the typical 9V. As batteries are expensive, I have opted to build my own AC to DC circuit using a step-down transformer, filter caps and an lm317 to get the necessary 18V to the circuit. Here is where my query comes into play:

Since I'm running mains directly into the metal enclosure, I plan on doing this via a 3-prong cable and grounding the enclosure to earth for the sake of safety. In doing so, am I creating a ground loop or other grounding issue, as the jack sleeves are not insulated? Would this work without needing to obtain plastic/insulated jacks?

TIA

[idy]

Gods and Monsters man, be careful.
Welcome to the forum.
How many Darwin Award winners begin their stories with

So after poking around the internet for a few days, I

decided to....

Good on you to think twice about this.

Welcome again.

[liquidgunsmoke]

Thanks for the welcome!

This has to be the funniest way to warn someone about high holtage I've ever read    rest-assured, I have 20 years experience as a hobbyist and have built countless devices stepping-down the voltage inside the unit and properly grounding to earth. However, this is my first time trying my hand at a stompbox... Things like "ground loops" and audio hum have not really been something I've previoualy needed to consider in a design. Though I do always appreciate and support someone providing a warning 

[idy]

Glad to bring a smile. You never know how much or little people know. And we are playing with fire, aren't we?

Every stomp box on the market uses a two conductor cable to bring DC to it right? Well, Line 6 use AC, but still low voltage and isolated from mains...

You intend to put a power transformer inside you pedal and run 120 (or 240) to it? Just like an old big box electro harmonix or univibe or something...

Then your amp will have a path to ground that your guitar and pedals will share, and you will have another path to ground through this Supa Sustainer?

One really cool thing about pedals and pedal boards is being able to run DC to them and not having to run a bunch of AC cords to each one.

Ground loops are a thing.

Why does this seem like a good idea? The big advantage over just using a 18V dv adaptor is:

[liquidgunsmoke]

Well, the advantage being that I'm on a budget and unfortunately don't have a commercially built 18v transformer handy... In such instances, building my own has sufficed. But now I'm entering unknown territory with raw audio. I'm not much of a pedal enthusiast (don't stone me, folks!) and have only ever had two max hooked up at a time; hard for me to justify a whole pedal board, especially since my rig hardly ever moves. I'm just in need of a compressor at the moment and had the parts to assemble one.

Yes, the amp and now this pedal would each have their own ground, but that ground is then shared on a power strip going to a single outlet. From what I've gathered, this should eliminate a problematic ground loop in that situation (but do feel free to correct me)

The other two pedals came with their own PSU's... Two prong, so no earth ground on them.

Edit: 120V mains line

[bluelagoon]

Go to a junk shop and purchase a second hand 18V or 24V PSU cheap as chips, or alternatively pick one up off the side of the road left out for council hard rubbish pickup. Its got to be a safer, easier orchestration than 120 volt into a metal case pedal with all the potential downside there. Those days are gone like the dinosaur.

[stallik]

Perhaps placing your power supply in a plastic enclosure and running the 18v to the pedal?

[DIY Bass]

I am sure that I have a few old laptop supplies in the shed that put out about 18V.  It should not be hard to track down something like that for not much money I would have thought.  Possibly even free from someone with a dead laptop.  The connector on mine are not the same as a pedal connector, but that is probably good as well - put a laptop jack on the pedal and then you can't accidentally plug the wrong supply in.

[antonis]

Perhaps placing your power supply in a plastic enclosure and running the 18v to the pedal?

With primary and secondary fusing, of course..

P.S.1
Fixed voltage regulators (like 7818) are cheaper than variable ones (like 317/350)..
In your case, due to low current draw, you can go even cheaper using 78L18 (TO-92 package)..

P.S.2
Welcome, also..

[liquidgunsmoke]

Perhaps placing your power supply in a plastic enclosure and running the 18v to the pedal?

Bingo! Sometimes one just needs a fresh set of eyes to help them think outside the box (literally)

Perhaps placing your power supply in a plastic enclosure and running the 18v to the pedal?

With primary and secondary fusing, of course..

P.S.1
Fixed voltage regulators (like 7818) are cheaper than variable ones (like 317/350)..
In your case, due to low current draw, you can go even cheaper using 78L18 (TO-92 package)..

P.S.2
Welcome, also..

Always, always 
And thank you!



My initial thought was first to find one already constructed, but in my years of looking around for other parts, I don't remember the last time I've seen an 18v PSU, if at all. Usually, if it's not 5v, 6v, 9v, 12v or the occasional 24v, it's something highly specific like 8.7v 

Thank you all for the replies!

[bluelagoon]

I think DIY Bass has the right idea,

Laptop PSU's with 19V supply, near enough

From Ebay, Cheap as chips

https://www.ebay.com.au/itm/264749850285?hash=item3da4521ead:g:d5AAAOSwqKpgwcSW&amdata=enc%3AAQAIAAAAwG6kxUR%2FswLEaZmSa7RO2LlFF7EmZFZS8C1OWGORmLbNX9V1%2B89B75s1%2BQiENAGZHVMGWjBjD4toQ3A3reKm8npZlVr3mZ4PkFJMxQc3mF3LJ%2ByUvMhluFoMVBvwTJm1JOkiSUBJnnos9F7N7ShGZHmAnkqkcwROFTjZPsAv%2BRrZJuJN3Ei3rSrdrJZZPUEgOtf3%2BHZSAX0PlLqHrVOS3yTCZAo46dVdKOfgKz8lYg6bYX%2FcKnJlcf6m7AaxgStJYw%3D%3D%7Ctkp%3ABk9SR7qboL6zYg

https://www.ebay.com/itm/266059910275?hash=item3df2680c83:g:W7IAAOSwSVBjoTR3&amdata=enc%3AAQAIAAAA4HS9%2BgqdCvTZQmPZCNzRjTnXkrysn%2BjfG4KK%2F8ehlQX%2BQ0OlM0zYtZP9RsrTPHPx%2BS8FgdNXjMChTEfRxkHFz4mOPxk0bO7rpNiy8IdrC0fJEL2CxLacIUsUJlpe2y7Zqt%2Bv1JwYxJW%2Ff9XrkJafkUx85qPI3Yuaa2jdtOanpgutcmG0yB97ehZikvMDctLbq%2FyugKNYjm%2BO%2FjLXNFLbFNrSN59qvVT%2BPcm%2BHtsG%2FNCYV%2FsxswyvGwPVmszEkVVy5if9zkTFAH%2BIFzgbQ04Ihk11ejgffAaeJbB8sgdXW13L%7Ctkp%3ABk9SR7qq0L6zYg

If these aren't cheap enough, don't know what is, and will save all the anxst and convolution of boxing and wiring your own.

And the fun in it all, is you get to spend more time with the grand kids, or out fishing!

[Phend]

Safety first,
Don't want to call you "sparky".