is it safe to run most pedals at 18v

[vick]

I have a customer that is asking me if it is okay to run a Vico Vibe at 18 volts.

I know all my capacitors are rated with room to spare, what else should I look for?

[Rolf Poti]

The biggest problem is usually the "gain stages"(IC:s, Transistors).
In this particular circuit you would probably need to switch some resistors to get the proper voltages on Collector and Base. If you dont you would likely destroy the transistors, or the circuit wouldnt work as it should.
I don't try my circuits with 18V unless it says they can handle it.

[vick]

Thanks

[IvIark]

Check the voltage rating of your caps, and the IC.  If the caps are rated at (I would recommend) 25V minimum then they will be ok.  Some ICs aren't suitable but most of the common ones we use are so you'll just have to check the datasheets for any you want to experiment with.  You may see some ICs are rated for +/- 12V, and these should be ok, because that rating equates to a 24V swing which makes them suitable for circuits running at 0 to 18V.

[vick]

no Ics just 5088 transistors
http://www.onsemi.com/pub_link/Collateral/2N5088-D.PDF

am I reading this right the the 5088 can take about 30 volts?

[IvIark]

Yes, you'll have no problems with most transistors

[vick]

thanks Mark, I appreciate it.

[induction]

One IC you have to watch out for (not in the Vico Vibe, though) is the LM386.

The LM386N-4 can go up to 18V, but any of the others (LM386N-1,LM386N-3,LM386M-1,LM386MM-1) can only handle 12V.

This is for ground-reference, too. Not bi-polar supply.

[Beaker]

Any idea why he would want to run it at 18V Vick? seems a bit of a strange one to me  - some circuits I can understand the benefits of increased voltage, but not this one. I can find no mention anywhere on t'internet of any mention of using 18V for this.

But yes, as Mark says, in theory, should be ok.

Just curious...

[vick]

this pedal is for sale in a shop and they accidentally grabbed an 18volt power supply when a customer tried it.  He liked the sound and claimed "with the 18V the pedal got a lot brighter and Fender sounding"

Personally I have no idea I do not own a 18 volt power supply.

[Dave]

Did they try it using the same guitar and amp but with the correct 9v to prove any difference?
Thanks
Dave

[Snare227]

Would running a pedal at 18V wired like the offboard wiring guide burn out the status LED if the resister wasn't increased?

[induction]

You can usually use the same resistor for both 9V and 18V, but the led will shine a little brighter at 18V, which may or may not be noticeable.

Here's the recipe:
A standard red led will drop around 2V from the anode to the cathode (this number is called Vf). That means there will be 7V left to provide current to run the led. If the resistor is R=2k2, then the current I through the led will be I=V/R=7/2200=3.2mA. The maximum current (Imax) through a standard red led is about 20mA.

Now switch to 18V: V=16V, so I=7.3mA. Well within allowable limits. To reach 20mA with this led and resistor you'd need a 46V DC supply.

The Vf and Imax of different leds depends on the specs (color matters, standard vs. ultra-bright matters, size usually doesn't matter). You can get a general idea from google even if you don't know the manufacturer or part number.

2k2 is a big enough current limiting resistor that you should be fine for any reasonable led. The only reason to adjust the resistor is if you want more or less brightness.

[Snare227]

Thank you very much Induction...... I love when you explain things out like this.