"active" power

robroe · Post by **robroe** » Fri May 30, 2008 1:45 pm

why do all these active pickups and active electonics for guitars run on 9 volts?

nothing fuckin runs on 9 volts anymore in the real world. everything runs on tiny batteries that you can fit in a watch, hearing aid, slim camera...fucking all sorts of shit.

if they made active electronics / pickups that could run off these kinds of little batteries it would make them so much more useful because you could just throw the thing in there under the stock control plate without routing the fuck out of your guitar n shit.

do you guys know of anything that doesn't run on 9 volts.....hell i think you could fit a AAA in there depending on the guitar

Justin J · Post by **Justin J** » Fri May 30, 2008 2:28 pm

design one and patent it.

NickS · Post by **NickS** » Fri May 30, 2008 2:35 pm

If you're using an op-amp there's a certain minimum voltage it needs to operate. The LM5534A datasheet specifes +/-3V minimum. That means you nead at least 6V. Either you need additional circuitry to boost your AAA battery's 1.5V up to that, which may be 85% efficient, put at least 4x AAA in or you take the easy option and use 9V. The other option is to convert to phantom power like they use for condenser mikes*, sending 9V along your guitar lead from your pedal board. Use capacitors each end to couple the signal onto the line. If it's a new build or you're happy to put a battery box in the back of your guitar you might get away with 4xAAA.

(*Note: one of the few applications where capacitors are still called "condensers")

Post by **Mike** » Fri May 30, 2008 2:38 pm

Two words:

Threshold. Voltage.

NickS · Post by **NickS** » Fri May 30, 2008 3:16 pm

http://www.edn.com/archives/1996/120596/25di_07.htm
Talks about a circuit to power some op-amps (e.g. LMC6681) that work from 1.5V, from a 1.2V alkaline battery.
It draws around 20mA, which means you'll probably be replacing the batteries a bit more often than with a low-power op-amp like EMG uses. LMC6681 noise is 32nV/Hz^-2 vs. 4nV/Hz^-2 for the LM5534A, so noise power is 18dB less with the higher voltage device.

Post by **Mike** » Fri May 30, 2008 3:19 pm

It all comes down to the breakdown voltage needed to make Si/Ge Diodes conduct though, be they discrete or in op-amps etc.

robroe · Post by **robroe** » Fri May 30, 2008 3:33 pm

how many volts are those round flat battries ?

EDIT: THESE http://www.energizer.com/products/speci ... emote.aspx

Post by **Mike** » Fri May 30, 2008 3:36 pm

Generally ~1.5V

robroe · Post by **robroe** » Fri May 30, 2008 3:41 pm

ok i finally found thier catalog

http://www.energizer.com/products/speci ... talog.aspx

the coin lithium ones are 3v.

....three rows up from the bottom on the right hand side is something called Alkaline A23BP

thats 12V and it looks tiny, like it shows little drawings of car door openers n shit.

NickS · Post by **NickS** » Fri May 30, 2008 3:42 pm

Mike wrote:It all comes down to the breakdown voltage needed to make Si/Ge Diodes conduct though, be they discrete or in op-amps etc.

True, but he's asking why they don't make them to run off widely available batteries. They could, but they'd use more current (maybe using an inverter or charge pump) or be noisier or both. Headroom might be another issue, you don't want the pickup output to overdrive the thing.

robroe · Post by **robroe** » Fri May 30, 2008 3:42 pm

the disk things look like the same diameter as the bottom of a vol. pot

Post by **Mike** » Fri May 30, 2008 3:44 pm

NickS wrote:
Mike wrote:It all comes down to the breakdown voltage needed to make Si/Ge Diodes conduct though, be they discrete or in op-amps etc.
True, but he's asking why they don't make them to run off widely available batteries. They could, but they'd use more current (maybe using an inverter or charge pump) or be noisier or both. Headroom might be another issue, you don't want the pickup output to overdrive the thing.

PP3's are widely available batteries. You can buy then in a petrol station, supermarket etc. Not so obscure watch batteries.

robroe · Post by **robroe** » Fri May 30, 2008 3:47 pm

lets do a + / - here

+'s
9 volts are cheap
a smaller battery than a 9 volt you wouldn't have to fuck up your guitar to use the product

-'s
9 volts you have to carve a giant chunk of wood out of your guitar
small, wierd batteries are more expensive / harder to find*

*if you consider going into your walgreens,eckard,rite aid drug store that sell these batteries thats on every other corner in your shithole town in america

robroe · Post by **robroe** » Fri May 30, 2008 3:48 pm

i would gladly pay up to five or 10 times as much for a wird small battery if i didn't have to fuck my guitar all up to get it in there

Post by **Mike** » Fri May 30, 2008 3:56 pm

I dunno why you would care either way. If you put active electronics in your guitar you're a chonst either way.

robroe · Post by **robroe** » Fri May 30, 2008 3:56 pm

did i just come up with some sort of radical new idea that no one else has thought of doing yet?

it seems like a fairly practical idea.

i wonder if aen could get one of his crazy fuckin things to work on these fucked up small batteries

robroe · Post by **robroe** » Fri May 30, 2008 3:59 pm

Mike wrote:I dunno why you would care either way. If you put active electronics in your guitar you're a chonst either way.

this whole idea of the SD blackout single coils that i posted in frans mustang pickup thread. being able to wire them up to a 2 way to boost that shit up when ever you want sounds awesome. but im not putting a big hole in my guitar to do it.

ESP is making new gadgets too like a scoop knob, a mid boost knob. like everything is right there in the knob. but you need a battery to run it.

Post by **Mike** » Fri May 30, 2008 4:03 pm

That's what pedals and amplifiers are for.

Post by **Mike** » Fri May 30, 2008 4:04 pm

Also the "in-guitar" gadgets is nothing new. it's been around for yonks, either in Passive Form (Black Ice) or stuff like this:

robroe · Post by **robroe** » Fri May 30, 2008 4:06 pm

http://img3.musiciansfriend.com/dbase/p ... 550000.pdf