DC over and under voltages and effect on effect components : good or bad ?

Generally, under-voltage conditions will do no damage to electronics.

Where it can cause damage is devices that are fan-cooled because the fan doesn't spin fast enough to properly ventilate the jellybeans in the circuit.

With effects pedals and the like, under-voltage conditions will make the device behave oddly or not operate at all.

You're probably aware of the trend that started about 20 years ago where certain players claimed they got better tone from a stompbox with a partially-drained battery. Power supply makers jumped on the bandwagon [har!] and offered units with 'simulated battery sag' and other dopey names to re-create the springtime-fresh creamy endless sustain of your favorite axe slinger. I've tried it with a bench power supply and it does affect how distortions and overdrives chop up the sine wave. Whether it's better or not depends on your ears and your biases.

Not exceed the current draw ? Aww...what's the fun of that ?

So how does one find out the real current draw of a pedal ?

I have a multimeter with two pins, and a small barrel connector at the end of a wall wart.

This does not compute.

Current draw measurements are easy if you make some basic patch cables and use a clamp meter.  You need to separate the power supply conductors and take a measurement from one of the conductors.

An interesting aside is the way GFCIs (called RCDs in the UK) cut power: they have a sense coil on the conductors, but instead of measuring the current, they simply compare the current of the hot and the neutral conductors. When the current in both conductors is equal, all is good. If there's a short to ground or other fault down the line, the GFCI senses the current disparity (usually they trip in the 10 microvolts range) and it opens the hot side of the circuit. This prevents shocks.

The simplest way to measure current is with a clamp meter or a clamp probe that plugs into a meter that can measure DC amperes. Many circuits draw current differently depending upon whether they are idling or under load, so it's good practice to take readings in both conditions.

I have a small handheld clamp meter made by Uni-T model 210E that was inexpensive and accurately measures down to microvolts AC or DC.


Pretty much all pedals these days have a label on the bottom that shows power jack polarity, voltage required, and current draw, like this:

"Ooh Ooh....I need a PTB-1 !! Maybe a dozen."

gbfun, the Talent Booster pedal works fine, but I usually recommend the pGOO BS-3 Blame Shifter over the TB-1 because it has more features:

Dang ! I need a BS-3 too ! You have all the good stuff Peegoo.

I have to make do with Dream On Distortion, and Chorus for Losers.

As for my latest ebay debacle, it seems to support the mixing and matching of parts in electronics.

I bought a Mooer PE100 and the selector knob was inaccurate and slow, the status light would blink off and on randomly, and worse, in acoustic mode, there was an obvious subtone that sort of breathed like a bad compressor, making it unusable.

And since I bought it over the holidays with lots of stuff, I didn't get around to testing it until late so I thought I was out the money.

And I would have been, but I looked inside and this supposedly "new" device had a circuit board stamp from 2016 !

I was expecting no less than 2018 or 2019 so I went back to the seller and gave him a picture.

He contacted his supplier or the factory and they told him that the circuit board was a Research and Development version and was not the production board !

Thankfully, my seller was nice enough to refund my money.

But one wonders just how a clearly flawed R and D board managed to get where I found it.

There were very fine lines in the plastic under the selector knob so I suspect someone did a sneaky substitution.

Or it could have been an old demo.

Hard to say.

Unfortunately, looking under the hood is frowned upon and that usually ends any chance of a refund.

So it's just best to send things back if it doesn't work.

But this time, I looked, and if I hadn't, I'd have another $50 paperweight.

Got lucky with an honest seller !

This time. But yes, it seems buying electronics is getting riskier.

I've seen one fake Les Paul, and 3 fake Strats in our hapless local pawnshop too.

And not so long ago they stopped $900,000 in fake dollar bills on the Canadian border.

And everyone knows about fake websi….umm.

Later.

Peegoo, I love your sense of humor, but your talent leaves me more in awe! How on earth do you do these? What do you use? 
BTW: How much are the TB-1 and BS-3. I could probably benefit from both LOL (BS-3 leaves another phrase in mind  )

Oh that's hilarious ! I have one of those except it's labeled differently. Same result though !