Boost on 1.5v lithium batt?

[m_charles]

Hello.

How much boost and batt life do you think you could squeeze out of a 1.5v "hearing aid" style battery if there is no LED? If my research is correct, a JFET would draw the least current.

Usage I'm thinking of is a boost to place into a guitar cavity. One that won't require a 9v batt. Is the 1.5v even capable of supplying the needed headroom to keep the signal clean?

Thx!

[ElectricDruid]

I got my friend's black Strat on the oscilloscope one day and the high strings put out about 100mV, but the low strings can produce as much as 1Vpp. So 1.5V isn't going to give you much of a boost. And that's a basic strat, no humbuckers, no extra-hot pups, nothing. Maybe some old tele will produce less, but I reckoned that his particular guitar was about as "typical" as guitars get (which is "not very").

How about trying with some other lithium battery? There's a ton of 6V and 12V options for cameras and stuff you could use.

[m_charles]

I got my friend's black Strat on the oscilloscope one day and the high strings put out about 100mV, but the low strings can produce as much as 1Vpp. So 1.5V isn't going to give you much of a boost. And that's a basic strat, no humbuckers, no extra-hot pups, nothing. Maybe some old tele will produce less, but I reckoned that his particular guitar was about as "typical" as guitars get (which is "not very").

How about trying with some other lithium battery? There's a ton of 6V and 12V options for cameras and stuff you could use.

Good idea! Figured I'd ask about the minimum volts to start, haha. Guess I could get one of those holders to run a couple batts at the same time also.

[antonis]

As Tom already mentioned, it depends both on signal amplitude and desirable gain..
A self-respected boost should exhibit about 12dB gain, meaning 4X..
For 1V_p-p and 4X gain, 4V power supply is marginally needed..
(5V is closer to safe and 6V are more than OK..)

[diffeq]

As Tom already mentioned, it depends both on signal amplitude and desirable gain..
A self-respected boost should exhibit about 12dB gain, meaning 4X..
For 1V_p-p and 4X gain, 4V power supply is marginally needed..
(5V is closer to safe and 6V are more than OK..)

one possibility is DC-DC boost from 1.5 to 5v (TPS61070 works down to 0.9V) and low noise, low current op-amp... but why bother when you can get bigger battery?

[Rob Strand]

You could start with a common CR2032 Lithium battery, that's 235mAH @ 3V.   Perhaps even two of them in series.

https://data.energizer.com/pdfs/cr2032.pdf

FWIW the hearing aid batteries are 1.4V, they are traditionally Zinc Air for high capacity per unit volume.  Some of those aren't much more mAh than the lithium button.  And remember they are 1.4V each compared to 3V of the lithium, same mAh at higher voltage is more energy.

You could try get more swing by using a push-pull differential output design but it will complicate the switching.  You would experiments to see if the floating outputs panned out.   Making the pickups differential is an option but I suspect it's going to cause issues getting tone pots etc to work.   I don't have a lot of faith in either scheme.

A cheats booster would be a low voltage preamp feeding a transformer for voltage gain.

[antonis]

As Tom already mentioned, it depends both on signal amplitude and desirable gain..
A self-respected boost should exhibit about 12dB gain, meaning 4X..
For 1V_p-p and 4X gain, 4V power supply is marginally needed..
(5V is closer to safe and 6V are more than OK..)

one possibility is DC-DC boost from 1.5 to 5v (TPS61070 works down to 0.9V) and low noise, low current op-amp... but why bother when you can get bigger battery?

Personally speaking, I don't bother at all..
(I was just trying to explain OP the margins of power supply voltage and undistorted boosted signal..)