Protecting against OVERVOLTAGE!

[Govmnt_Lacky]

Recently I have been building with some components in different circuits that have maximum Vin values. Most of them have a Vmax of around 12V. So here in lies the rub:

Most generic wall warts (9V and above) put out MORE than 12VDC. The one that I have is labeled 9VDC at 200mA... BUT, when I put it on a meter it is actually putting out around 14.5VDC 

I have noticed that this is a trend with wall warts. I also have a 12V that puts out 17VDC!

So my question is... How does everyone protect their components from overvoltage?

Do you insert a regulator circuit into EVERY build that is questionable?

OR

Do you exclusively use regulated power bricks? (i.e. One Spot, Voodoo Labs Brick, etc.)

[slacker]

Unregulated wallwarts give you the voltage they claim when you draw whatever current they are rated at, if you draw less current than this then the voltage will be higher if you draw more the voltage will be lower. So for example your 9 volt one will give you 9 volts if you draw 200mA from it.

I only use regulated supplies for my pedals, either a no name "power brick" or a DIY one. Other than using passive components that are rated for well above 9 volts, I don't bother adding any over voltage protection but if I was making a pedal for someone else or selling them then I would.

[merlinb]

Recently I have been building with some components in different circuits that have maximum Vin values. Most of them have a Vmax of around 12V.

What parts are only rated for 12V?
Most pedals use transistors, opamps and caps that can take upwards of 20V without dying, so a few extra volts from a cheap wallwart is not a problem. The few that use 5V logic ICs invariably use voltage stabilisers, but that's a necessity since even 9V would be too much for them.

Also, unless the pedal has a voltage stabiliser, any self-respecting musician who values his signal-noise ratio should use a regulated supply.

[R.G.]

Do you exclusively use regulated power bricks? (i.e. One Spot, Voodoo Labs Brick, etc.)

It's up to YOU, the designer, to make sure that you pick parts that work with the power supply you intend to use. If YOU don't say "only use a 9V regulated" or "12V regulated" or "0-18V AC or DC" or something, you can't really expect that any wall wart you plug in will work.

Almost all commercial pedals not of the "boutique" persuasion say on the box something like "9V battery or regulated 9Vdc adapter". They may, if they're being kind, tell you that above 12, 15, 18, whatever volts will cause permanent damage and void your warranty.

So yes, almost all people who haven't given in to the dark side use 9Vdc regulated adapters. Most of the DIYers here have even built 9Vdc regulated power sources. The experimenters will play with more than that, but at their own risk.

You cannot in general just plug in some power supply to any piece of electronic equipment and expect it to survive or work properly if you don't feed it the amount and kind of power it expects.

Most generic wall warts (9V and above) put out MORE than 12VDC. The one that I have is labeled 9VDC at 200mA... BUT, when I put it on a meter it is actually putting out around 14.5VDC

I have noticed that this is a trend with wall warts. I also have a 12V that puts out 17VDC!

This is a well known phenomena that I've explained here several times. Transformers are specified to give you, for instance, 12Vac at 300ma. That means that it will give you AT LEAST 12V when loaded down with 300ma. The makers are usually pretty quiet about what it does at lighter loads unless you pin them down. The smaller the transformer, the more internal resistance it has, so the more the no-load voltage has to be jacked up to keep the output at rated maximum current up to spec. It's not a trend - it's physics.

So my question is... How does everyone protect their components from overvoltage?

I use regulated power adapters for mine.

Do you insert a regulator circuit into EVERY build that is questionable?

Why is the build questionable? If you build it, you know what parts are in there, and what maximum power supply will kill it, yes? And you are the one who puts the power supply on it. Either pick a power supply that you've tested and know about, or get one that's regulated. Or put a regulator after the power supply and force the output voltage to be what you want.

Just to close the loop, you can't expect any random piece of equipment to work with power supplies you don't know the nature of. You can't use a generic wall wart and ... Well, I guess you *can*, but the results won't be uniformly good.

[petemoore]

  The Spyder article at GEO describes the power supply.
  There are buyable alternatives such as Voodoolabs PPII others.
  I have one of each here.
  Quite a lot like just using a battery, very steady DC, no ripple on a floating voltage puts a lid on the "Noise Whack a Mole" so everytime you slap a box with the correct polarity/floating/regualted/filtered power supply the noise mole has 1 or more less places for it's ugly head to pop up.