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Author Topic: Leakage  (Read 2938 times)

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Offline BrainfarthTopic starter

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Leakage
« on: July 27, 2015, 02:08:44 am »
  I threw together a bluetooth speaker with some junk laying around and ran into an odd problem. With the switch off, I'm getting enough voltage to light the LED on the amp. I would rather not have to install two power switches. Attached to this message is my rendition of the wiring.
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Offline SL4P

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Re: Leakage
« Reply #1 on: July 27, 2015, 02:19:50 am »
Voltage to the amp between the top rail, and the 7805 (floating at top rail minus 4 cells)
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Offline w2aew

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Re: Leakage
« Reply #2 on: July 27, 2015, 03:10:17 am »
Change to DPST or DPDT?
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Offline BrainfarthTopic starter

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Re: Leakage
« Reply #3 on: July 27, 2015, 03:44:10 am »
The rocker switch that I'm using is a single. I was hoping that someone had an elegant solution. I have a pile of components laying around and could possibly throw something together. But unfortunately, I don't have any relays.
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Offline Monkeh

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Re: Leakage
« Reply #4 on: July 27, 2015, 03:46:38 am »
Put a diode before the regulator.
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Offline BradC

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Re: Leakage
« Reply #5 on: July 27, 2015, 03:50:22 am »
That configuration is going to create quite the imbalance across your batteries. You'll need to look at that when you charge them also.
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Offline BrainfarthTopic starter

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Re: Leakage
« Reply #6 on: July 27, 2015, 04:12:25 am »
The regulator is a L7805CV from china. Do you think it would hold up very well against a max of 18v input? The bluetooth receiver hardly draws anything. If that's the case, it would solve the rest of my issues.
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Offline BradC

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Re: Leakage
« Reply #7 on: July 27, 2015, 04:16:13 am »
Quote from: Brainfarth on July 27, 2015, 04:12:25 am
The regulator is a L7805CV from china. Do you think it would hold up very well against a max of 18v input? The bluetooth receiver hardly draws anything. If that's the case, it would solve the rest of my issues.

Datasheet says 35v.
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Offline BrainfarthTopic starter

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Re: Leakage
« Reply #8 on: July 27, 2015, 05:26:22 am »
  I guess the only reason I questioned the higher voltage is that I've heard that they get very inefficient.  Or is this not going to be an issue because the bluetooth receiver draws such a small current?
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Offline BradC

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Re: Leakage
« Reply #9 on: July 27, 2015, 06:09:36 am »
Quote from: Brainfarth on July 27, 2015, 05:26:22 am
  I guess the only reason I questioned the higher voltage is that I've heard that they get very inefficient.  Or is this not going to be an issue because the bluetooth receiver draws such a small current?

That depends entirely on exactly what "small current" means and it's entirely relative. A couple of 10's of milliamps and you'll be fine, much more than that and you'll want a heatsink. Why not buy one of those $2 buck converter boards from China and have it both ways?
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