Simple question about 9V adaptors

[glops]

I use a 9V battery to power my breadboard prototyping board but would like to start using a plug 9V adaptor.
If I had an adaptor for a Sony disc man or similar electronic device could I use that instead of buying an
adaptor specifically made for pedal use? 

I guess I need to know if such an adaptor is regulated or not. I would like not to buy an expensive pedal power box.  If using
what I have on hand is a no go, can anyone suggest a good regulated power supply with a good price?  Basically, something
that only needs to power a breadboard setup...  Starting to use chips and am concerned about battery drainage...

Thanks!

[dougman0988]

In general any old wall adapter will work fine.  It's just a power supply and it should be able to be used for anything.  Of course you'd want to make sure it can provide the current you'll need, but pedal circuits don't consume that much at all and nearly all wall adapters should be able to provide more than enough.

[01370022]

Just check voltage out (what voltage it supplies) and what current its rated to supply. Read your stompbox specs (on the bottom usually) and find the current draw. Add up all the current draws for all your pedals and make sure the rating on your PSU is equal to it (unregulated supply). If you have a regulated supply, just make sure the current rating is larger than the draw.

As Dougman said, most pedals don't consume much, but if you have any digital pedals then these can get pretty thirsty.

Make sure to check the polarity too.    I've stuffed that one up. Most guitar pedals seem to be center pin negitive I've found.

[glops]

thanks

[GibsonGM]

Make sure to check the polarity too.   Wink I've stuffed that one up. Most guitar pedals seem to be center pin negitive I've found.

A reverse-biased diode added across the power supply input terminals in your pedals (1N914 type) can offer a measure of protection against a reversed power supply connection. It will conduct if the power's connected backwards, and short itself out hopefully before your pedal is damaged.  Nothing you'd seriously RELY on, but just in case...it's happened to us all, ha ha 

[Mark Hammer]

This comes up regularly.

Not all 9v adaptors are created equal.  Even IF the voltage and current are appropriate for your needs, and the plug has the right orientation (outside pos) and hole size (2.1mm), there is still the matter of the degree of regulation provided.  If the power is "under-smoothed", it can provide annoying hum in your signal.  Keep in mind that if one had a 4-diodes-and-a-cap wallwart that does the normal things with respect to converting AC into DC, that smoothing capacitor could be 1000uf, or 470uf, or 220uf, or even 100uf.  The smaller it is, the less smoothing and the more hum.

This is not to say you should expect trouble.  Rather, do not simply assume that if it is electronically up-to-spec it will be sonically up-to-spec.  It may be the case that you need to add a little more capacitance to keep that pesky residual hum out.  The capacitance can be added at the point where the adaptor feeds the pedal.  It can be added by attaching a parallel electrolytic cap to the power cable.  Or you might consider what I have referred to over numerous posts as a "power distribution box".  That is, a little plastic box with an input jack for the wallwart, a couple of output jacks for power cables to run to your pedals, and some additional regulation and a power-status LED in between..  The nice thing about such a box is that you can leave it secured to a pedalboard, and simply unplug the wallwart from the box when you want to power down and pack up.

[Skruffyhound]

Like this maybe

http://www.beavisaudio.com/projects/Huminator/index.htm

[glops]

Thanks for the info guys!  I think I'm going to get a One Spot soon.  Basically, I have been building pedals with a battery only because I hate cords but am gonna start putting in DC jacks and using AC is probably a good idea to have for my prototyping set up...

[petemoore]

  Make sure it's not an AC adapter to DC circuit supply, actually what does the pedal call for PS wise of course the first step, then polarity.
  Then all powersupplies aren't equal. "DC" isn't perfect, it always moves a little bit.
  An example of a good 'stiff', ripple-free power supply is a battery, it makes an excellent comparator to any other DC source.
  Otherwise ripple-free is not too hard to get from a "DC" power supply by adding a regulator, see data sheet about the 'extra' 2 volts it requires for operation.
  The WW you choose that says say 12v output is probably made to have about 12v when near it's current supply limit, deal is that without a load or with a light load, the voltage rises, measureing with the intended load, or unloaded...and hopefully that'll come out to be less than what the rated limit turns out to be.

[glops]

Thanks, Pete.

Can you recommend a power supply source?   If I want to save my batteries, want a wall wart, what is a good solution?

All I want is something that will give me 9 volts, negative ground.  Just a basic regulated supply...

[jkokura]

The Boss power adapter is decent. Many also use the Godlike onespot. I use the boss cause that's what I have.

Jacob

[WhenBoredomPeaks]

I didn't want to open a new topic for the problem:
So i made a hybrid power filter-voltage sag-daisy chain thingy.
Individually the DC output jacks work, and the sagged outputs too, but when i connect more than one effect the voltage drops below 9V (which was the input) like it was a series circuit.
I tried it with 3 different regulated and unregulated adapters.
But it's parallel to my best knowledge. So there shouldn't be voltage drop.

Here's a selfmade pic of the circuit:



So basically its a Beavis hum-debugger and voltage sag circuit.

[glops]

Thanks, was looking at the godlyke one...

[chi_boy]

I heard that the Ibanez AC109 was supposed to be really good for the money, but I haven't tried it yet.  I read that while looking for an adapter for a different project.

http://accessories.musiciansfriend.com/product/Ibanez-AC109-9V-DC-Power-Supply?sku=150240

[WhenBoredomPeaks]

I didn't want to open a new topic for the problem:
So i made a hybrid power filter-voltage sag-daisy chain thingy.
Individually the DC output jacks work, and the sagged outputs too, but when i connect more than one effect the voltage drops below 9V (which was the input) like it was a series circuit.
I tried it with 3 different regulated and unregulated adapters.
But it's parallel to my best knowledge. So there shouldn't be voltage drop.

Here's a selfmade pic of the circuit:



So basically its a Beavis hum-debugger and voltage sag circuit.

Anyone see any cause of voltage drop on the picture with more than one pedals plugged in? Is there a series connection somewhere? Or voltage sag circuits and daisy chains are not meant to go together?

[jkokura]

I heard that the Ibanez AC109 was supposed to be really good for the money, but I haven't tried it yet.  I read that while looking for an adapter for a different project.

http://accessories.musiciansfriend.com/product/Ibanez-AC109-9V-DC-Power-Supply?sku=150240

The power ratings on that seem identical to my Boss unit at first glance.

Jacob

[zombiwoof]

The Danelectro 9V adapter is only about $8 and works fine for me.  I got it for my Mojo Vibe and have used it with many other pedals.

Al

[PRR]

> it's parallel to my best knowledge. So there shouldn't be voltage drop.

Parallel just means all loads get the same voltage. They sag together.

The lights and pump in my house are all parallel off the 120V breaker-bus. When the pump kicks in, the lights dim. I have measured 126V just-lights, 112V pump starting, 122V pump running. That's the same whether I measure at the breakerbox or at the lights.

Where is this sag coming from? I have 400 feet of skinny wire to the street. I done the math, the sag is just about what you expect from that big a pump on that long of that skinny wire.

Yeah, usual electric guides suggest less drop, primarily so the homeowner doesn't complain about the lamp-flicker. It isn't in real danger of overload, just saggy. And looking at the cost of 400 feet of fat new wire through the bog, I'll live with the sag.

Where is your sag coming from? What is your "9V IN"? If it is a battery, well, most pedals put a good load on a battery, multiple pedals sure could sag a battery. Even a wall-wart will sag.

Ah! You have R1, 100 ohms. One thrifty pedal, 1mA, makes 0.1V drop, negligible. One medium hungry pedal, 10mA, makes 1V drop. Three 10mA pedals makes 3V drop, and now you are sitting low for 9V gear.

Back to my house. I "could" leave the heavy pump on the existing wire, and add another wire from the street just for the lamps. Assuming the street transformer was rock-solid, pump-start would cause NO lamp sag. I could run separate 400-foot wires for the dryer, blower, saw, other loads, and nothing would cause sag in any other line. When it is $5,000+ labor per line (plus wire), that's costly.

But you could and should run a separate 100r 100uFd cap for -each- output. The battery/wart would still sag, but much less than a 100r resistor shared among all outputs.

(I see the 47nF cap as unnecessary, but do it if you want.)

[WhenBoredomPeaks]

> it's parallel to my best knowledge. So there shouldn't be voltage drop.

Parallel just means all loads get the same voltage. They sag together.

The lights and pump in my house are all parallel off the 120V breaker-bus. When the pump kicks in, the lights dim. I have measured 126V just-lights, 112V pump starting, 122V pump running. That's the same whether I measure at the breakerbox or at the lights.

Where is this sag coming from? I have 400 feet of skinny wire to the street. I done the math, the sag is just about what you expect from that big a pump on that long of that skinny wire.

Yeah, usual electric guides suggest less drop, primarily so the homeowner doesn't complain about the lamp-flicker. It isn't in real danger of overload, just saggy. And looking at the cost of 400 feet of fat new wire through the bog, I'll live with the sag.

Where is your sag coming from? What is your "9V IN"? If it is a battery, well, most pedals put a good load on a battery, multiple pedals sure could sag a battery. Even a wall-wart will sag.

Ah! You have R1, 100 ohms. One thrifty pedal, 1mA, makes 0.1V drop, negligible. One medium hungry pedal, 10mA, makes 1V drop. Three 10mA pedals makes 3V drop, and now you are sitting low for 9V gear.

Back to my house. I "could" leave the heavy pump on the existing wire, and add another wire from the street just for the lamps. Assuming the street transformer was rock-solid, pump-start would cause NO lamp sag. I could run separate 400-foot wires for the dryer, blower, saw, other loads, and nothing would cause sag in any other line. When it is $5,000+ labor per line (plus wire), that's costly.

But you could and should run a separate 100r 100uFd cap for -each- output. The battery/wart would still sag, but much less than a 100r resistor shared among all outputs.

(I see the 47nF cap as unnecessary, but do it if you want.)

Thanks for the detailed answer!

I will jumper the 100ohm resistor and gonna add the filters individually, i will probably solder them directly on the output DC jacks.
R1 and the 47nF cap was detailed in the Beavis hum-filter as forming a low-pass filter to filter out some audible noise, but now i see it can cause some problems. I will remove the resistor.