Assembling a digital voltage display

Any device you put on to monitor your batteries is going cause more drain. Instead of LED type, you might want to consider LCD, or perhaps a low battery warning with no display, something that beeps when you need to replace the cells.

My 2 cents worth anyways... (and that's CDN cents too...)

- Tim -

LCD would be fine. A bit less visible, but not a big problem. As far as the beep idea, it would never be heard during a performance.

Well my idea of a low battery warning, would be at the point where you would have less than a few hours left on cells, not when you had a few minutes, so if you had a beep before the set, you changed batteries. A beep after or during the set would not be a concern, as you would have enough power to finish the set.

- Tim -

That's your best option. Get some Velcro with adhesive backing, and hang the voltmeter on the side of the amp.You can get a dirt cheap voltmeter on sale from Harbor Freight that will be fine for this function. It's on sale now for $4.99 - in the past it has gone for as low as $2.99. ITEM 90899-2VGA

Ed

Why so complicated? Why not a good old d'Arsonval movement? Drains microamps.

Needle type meter? I wondered about that, but I also wonder about durability. The bass doesn't get banged around much, but still....

And on the other hand, I've met old Simpson meters that never seem to die.

"JoeSpareBedroom" wrote in news:9Du_h.7835$ snipped-for-privacy@news01.roc.ny:

If you want a small battery level meter, a simple bar meter will do (button activated) , or even a simple comparater lighting a "battery good" LED, or a "battery low" LED

You could esaily attach a coaxial jack on each device you wish to test, and use an external tester that would be no bigger than a 9V battery.

Gary Tait wrote in news:Xns9927A51882C59wonkynillmailnil@142.77.1.194:

I was thinking this too. Never came up with the goods though so I let it go... I was thinking of MOSFETS. There might be a way to keep one turned off when the gate voltage is high enough, so that the total current draw is in the nanoamp range, but the LED begins to glow more as voltage falls. Obviously the limited remaining charge will be used even more rapidly, but usefully, and no significant drain would begin till there was a need to indicate. I'd hoped to work out something with one FET, an LED, and no more than two resistors, but it eluded me. Maybe it can't be done that simply, but it seems like the way to go, to get as close to that as possible.

by "JoeSpareBedroom" May 5, 2007 at 03:16 PM

Needle type meter? I wondered about that, but I also wonder about durability. The bass doesn't get banged around much, but still....

And on the other hand, I've met old Simpson meters that never seem to die.

rpbc: Why not build a regulated 9 volt supply and feed it from the power supply of the bass amp... or just buy a little wall type transformer of the right voltage wired to the bass amp power switch, and add filter and regulation to that? Then you won't have to worry about the battery.

Because I play 99% of the time with a Sennheiser wireless setup. I move around too much to have wires underfoot.

by "JoeSpareBedroom" May 12, 2007 at

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power

and

Because I play 99% of the time with a Sennheiser wireless setup. I move around too much to have wires underfoot.

rpbc: Oh, I see. Think I only got half the picture. Could you install a little female jack on the compartment wired to the battery and have a male plug on the leads of a voltmeter so you can just plug in an measure? You could measure with the unit on so the reading will be under load.

That's the solution I'm leaning toward right now. The compartment is precisely big enough for the two 9v batteries. I'm taking the bass to a luthier later this week to discuss the safest direction in which to rout out enough space for a banana jack, without threatening the integrity of the wooden body.