# Project help! power strip/guitar pedal combo idea

Discussion in 'The Projects Forum' started by Loker, Apr 29, 2015.

1. ### Loker Thread Starter New Member

Apr 29, 2015
2
0
Hi guys,

So I'm a relatively new Electrical Engineering student (taking my first circuits class) and I came up with an idea for a home project. The idea is to convert a power strip into something like a guitar pedal with a 1/4" input and output and a foot switch to turn it on and off. Some mechanism inside the pedal would amplify and/or measure the current from the instrument cable and send it both to the outlets and the output jack. Ideally, the current provided to the outlets would be proportional to the volume of the guitar and if you were to plug into the power strip, say, a few lamps, their brightness would change according to the volume of the guitar, which would create a cool effect for house shows, small bar shows, etc. To give you some context concerning my (very minimal) knowledge and some direction if you reply, here are some question I thought might be relevant to taking the first steps in the design process:

• Is this even possible?
• Would the system operate on an AC or a DC?
• Does the current in an instrument cable encode the volume of the instrument? Is it proportional to the volume?
• Can you modify an amplifier to provide current to the lamps (in series)?
• Can you split the current from the instrument cable into two identical currents? (One that would power the lamps and one that would be sent to the speaker)

If the idea is practically possible:

What do I need to learn in order to make it a reality? How can I learn it?
• What equipment do I need to buy?

2. ### #12 Expert

Nov 30, 2010
16,663
7,307
yes, DC, yes, yes, yes
You will need a power supply to run the splitter and the lights.
The light part is called a color organ. There are single chips that run a row of lights according to volume.

If I didn't cover everything, ask again.

3. ### blocco a spirale AAC Fanatic!

Jun 18, 2008
1,457
369
Surely, you must have seen sound-controlled lighting effects before?

The guitar amplifier and the lighting effect unit are two entirely different things. So, you are proposing a guitar/instrument amplifier the output of which is fed to a lighting effect unit; both these things have existed for decades.

Concentrate on the sound to light part, design for a 12v supply and use standard low-current LEDs as the output. When you get this part working, the output can be scaled up to drive higher power LED lamps.

Last edited: Apr 29, 2015
4. ### AnalogKid Distinguished Member

Aug 1, 2013
4,679
1,295
Not to be discouraging, be careful. Although color organs have been hobbyist/experimenter projects since the 60's, they can be dangerous. The circuit directly controls AC mains power to the lamps (unless you are going with all LED lighting). It can be done with no external power supply required if you use a small transformer to isolate the audio signal from the power line, but you get better control and performance if there are some electronics in there.

ak

5. ### Loker Thread Starter New Member

Apr 29, 2015
2
0
I would really like to design something that you can just plug normal (non-LED) household lamps into that would change brightness proportional to the volume of the guitar. Given those constrictions, how would you begin to design a prototype? As far as I can tell, an alternating current from the guitar would enter the system and would (ostensibly) need to be converted to DC, so the first thing in the circuit would be a mechanism that converts AC to DC. Then, we would need to split/duplicate the current so that one duplicated current is sent (and amplified) to the outlets to power the lamps, and one is sent to the output of the system. As far as a power supply goes, I know most pedals operate using a 9v AC adapter. Would this be an appropriate power source for the system to amplify the current that powers the lamps? If so, where would it enter the circuit? I'm sort of looking for an explanation that really dumbs down the process and goes into detail concerning each mechanism of the circuit.

6. ### #12 Expert

Nov 30, 2010
16,663
7,307
This sounds like, "I had an idea, so I will build it."
It requires a lot more than that.
I found a video that starts to explain some of this, but it's based on an Arduino...whatever that is.
Some kind of hobbyist computer module.
Color Organs have been around since the 1960's.
You can buy one, all finished. You can adapt them to work properly for a Led Zepplin concert.
Well...I can...If I have all week to do it.
From the level with which you describe your ideas, I am reminded of starting to show a person how, and it took an hour to get past, "This is why I use a soldering iron".
Take a peek. Maybe then you will have a better idea of where you want to start.

7. ### #12 Expert

Nov 30, 2010
16,663
7,307
Since when did a copy and paste of the URL import the whole video?

This might be a bother when I copy and paste a URL for a parts search page. What if it imports 65 pages of parts?

Apr 5, 2008
15,796
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9. ### #12 Expert

Nov 30, 2010
16,663
7,307
I did a, "copy & paste" of that URL from You-Tube. I did not expect to import the whole video!
It worries me. What if I type in, "www.mouser.com and this site imports the whole Mouser website?

What have I done? It seems wrong.

Apr 5, 2008
15,796
2,384
Hello #12,

A link to a youtube video will give an embedded video on the forum.
If you do not want the link to be converted to an embedded video use the plain tags.

Bertus

#12 likes this.
11. ### #12 Expert

Nov 30, 2010
16,663
7,307
Ummm...what's a "plain tag"? and how do I do that?

12. ### #12 Expert

Nov 30, 2010
16,663
7,307
Back to the subject. In the site Bertus linked to (post #8), there is a schematic of the project with a point labeled, "audio in" and the first question in the, "comments" section is, Where do I connect the left and right channels?
This illustrates the vast difference between somebody that knows how and somebody that doesn't. You need to find where you are on that spectrum of skills.

Apr 5, 2008
15,796
2,384
Hello,

You can do it like this:

This will give you:

Bertus

#12 likes this.
14. ### #12 Expert

Nov 30, 2010
16,663
7,307
Thanks. I can figure out how to do that easily enough.

15. ### blocco a spirale AAC Fanatic!

Jun 18, 2008
1,457
369
So, you think you should convert the AC signal from the guitar to DC then send half to the "household lamps" (which are AC, by the way) and send the other half into the audio amplifier (which also expects to receive an AC signal)? Do you understand the difference between AC and DC, voltage, current and power? Do you understand audio? Do you understand electronics? Would you like someone to explain all of these things to you?

Did you read my first post?

I really am trying to be helpful here but, clearly, before embarking on the process of electronic design, you must first (at the very least) understand basic electronics; this is obvious, wouldn't you agree? Otherwise, this will be a very very long thread. Just because you had an idea for something does not mean that you have the knowledge to put it into practice.

I believe there are some very good tutorials available on this site and that would be a good place to start.

Last edited: May 2, 2015
16. ### tranzz4md Member

Apr 10, 2015
152
28
What you and others may think of as "ordinary household type lights",,,,,, practically don't exist anymore in the US. The swirly florescents (including those inside a frosted glass bulb) and LEDs don't behave at all like incandescent "A" lamps.