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Topic: Sarno Earth Drive battery life |
Michael Hummel
From:
Ottawa, Ontario, Canada
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Posted 20 Nov 2013 11:24 am |
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I have a terrible habit of leaving the cable from my guitar plugged into the Earth Drive pedal when I'm finished practicing. Having done this countless times over the last months, and the battery lasting just fine until last night, I decided while I had the unit apart to replace the battery I would make some current measurements to satisfy my inner geek!
[I remember some time ago on the forum someone asked Brad what the current consumption of the Earth Drive was, and he (quite appropriately) said "very low").
I took my microammeter and put it in series with the battery lead and observed the following:
Nothing plugged in to the input jack: 0.0 uA
Cable plugged in, effect switched off: 1.4 mA
Cable plugged in, effect switched on: 3.9 mA
This is very low indeed! I suspect the difference between "effect off" and "effect on" is entirely due to lighting the blue LED on top to show the effect is on, so one could almost triple the battery life by disconnecting the LED.
People generally consider the Duracell alkaline 9V battery to have around 550 mAH (milliampere hours) of lifetime, so if you only rarely have the pedal switched "on", you could expect about 393 hours (16 days) of continuous operation.
I hope this might be useful to someone. Maybe you now know how often you should replace the battery to avoid mishaps at gigs!
Cheers,
Mike
_________________
MSA Classic 5+4
Too many 6-strings and amps to list |
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Craig Baker
From:
Eatonton, Georgia, USA - R.I.P.
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Posted 20 Nov 2013 3:36 pm
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Hi Michael,
Thank you for the interesting post regarding battery life. You are correct. . . LEDs do indeed draw current. One of my customers was so concerned, that he uses 10-year lithium smoke alarm batteries. They tend to be a bit expensive, but for him, it was a solution.
Sincerely,
Craig Baker 706-485-8792
cmbakerelectronics@gmail.com
C.M. Baker Electronics
P.O. Box 3965
Eatonton, GA 31024 |
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Lane Gray
From:
Topeka, KS
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Posted 20 Nov 2013 7:36 pm
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I'm curious: was the draw with unit switched on taken at idle, or while it had a signal it was applying gain to? RI seems logical that consumption would go up markedly with work
_________________
2 pedal steels, a lapStrat, and an 8-string Dobro (and 3 ukes)
More amps than guitars, and not many effects |
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Pete Burak
From:
Portland, OR USA
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Posted 21 Nov 2013 8:32 am
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Just curious why you don't get a power supply for it?
I am using a single Boss PSA-120T power-supply with a multi plug adapter to power mine. |
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Keith Hilton
From:
248 Laurel Road Ozark, Missouri 65721
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Posted 21 Nov 2013 10:12 am
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Michael I am surprised that you measured the current at 3.9mA, as I thought anything involving a LED would have more current draw. You can lower the current draw by lowering the resistor connected to the LED, but the brightness of the light will be less. The formula for figuring resistors for LEDs is as follows:
R=Vin-VLED-dividided by--ILED. This means volts in-say 9 volts, minus VLED, which is LED voltage drop-- normally around 1.7 volts,divided by ILED, which is normally the current rating of the lead--most common is 20mA. So if you used these figures the resistor would be 365 ohms.
There are new LEDs on the market that have a different voltage drop and different current rating. Hope this information helps. |
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Michael Hummel
From:
Ottawa, Ontario, Canada
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Posted 22 Nov 2013 10:39 am
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Lane: idle. No signal in, nothing connected at output. My hunch is you might see a tiny increase while processing a signal, but not much.
Pete: Thought about that; I happen to be playing 6-string, piano/organ, as well as steel. I already have too many things to lug around and plug in!
Keith: Modern high-brightness LEDs don't take much current to light up! If this one only takes a couple of mA to light up, I'd say that's pretty efficient!
Cheers,
Mike
_________________
MSA Classic 5+4
Too many 6-strings and amps to list |
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Keith Hilton
From:
248 Laurel Road Ozark, Missouri 65721
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Posted 22 Nov 2013 1:15 pm
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| I agree! 3.9mA to run a LED, and circuit containing and IC, or descrete transistors, is wonderful. |
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