Positive and Negative 5v from 2 AA Batteries

Click For Summary

Discussion Overview

The discussion revolves around designing a portable device powered by 2 AA batteries that requires both positive and negative 5V outputs. Participants explore various methods to achieve this dual power supply, considering factors such as application requirements, balance, and cost-effectiveness.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant notes that 2 AA batteries provide a nominal voltage of 3V in series and suggests using a voltage divider to create a midpoint ground for ±5V, although this method may be unbalanced.
  • Another participant, focusing on audio applications, proposes using three voltage regulators: one to step up 3V to 5V, another to increase this to a higher voltage, and a third to invert it to -5V, acknowledging that this approach is not ideal.
  • A different suggestion involves using separate DC-DC voltage converters for +5V and -5V or a single 10V output converter with a virtual ground, referencing a resource on virtual grounds.
  • One participant seeks recommendations for a step-up converter that can convert 2-3V to 10V, indicating a need for specific component suggestions.
  • Another participant recommends searching for adjustable voltage converters on Digikey, emphasizing the importance of reading datasheets for implementation details and efficiency considerations.
  • Participants express appreciation for resources shared, particularly a site focused on virtual grounds, which is deemed useful for audio projects.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method to achieve the required power supply, with multiple competing views and approaches presented throughout the discussion.

Contextual Notes

Some methods discussed may depend on specific application requirements, such as the need for balance in audio applications. The effectiveness of proposed solutions may vary based on component selection and implementation details.

robo171
Messages
4
Reaction score
0
I'm designing a portable device running off of 2 AA batteries that requires positive both positive and negative 5v power at the same time. What is the best/cheapest way to achieve this?
 
Engineering news on Phys.org
2AA batteries would only give you a nominal value of 3V in series. Otherwise it kinda depends on your application of the dual supply. The easiest and cheapest way would be to split a 10V source using voltage dividers. Create a ground at the midpoint and then the reference voltages would be +- 5V. Not super ideal obviously and prone to being unbalanced.
 
I'm working with audio, so balance is important. My best idea thus far has been to use 3 voltage regs: one to step up 3V to 5V, one to step up 5V to a slightly higher level, and one to invert the slightly higher voltage to -5V. Obviously that's not quite ideal either.
 
You could use one DC-DC voltage converter (regulator) for +5 V, and another one for -5 V (perhaps a http://www.exar.com/Common/Content/ProductDetails.aspx?ID=595" ). Or, you could use one 10 V output DC-DC converter and a virtual ground.

I found http://tangentsoft.net/elec/vgrounds.html" might not be a bad option if you use the 10 V converter option.
 
Last edited by a moderator:
MisterX: I found the page on virtual grounds very informative, especially for my project! Do you have a suggestion for a step-up that can convert 2-3V to 10V?
 
You could look on Digikey http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=2556570".

Select all the input voltage ranges with minimum voltages of less than 2.3 V or so. I didn't see any with fixed 10 V output so you may want to look at the adjustable ones with 10 V in the range of output voltages.

You may want to select "Through Hole" under "Mounting Type".

By reading the datasheets you can understand how to use the ICs and what other components you may need to have. There may also may be information on efficiency.
 
Last edited by a moderator:
Tangent's site is great especially if you are working with audio. I actually had a cmoy in mind when I was talking about a resisitive dividing virtual ground.
 
Thank you very much, MisterX. As I dig deeper into Tangentsoft, I keep finding valuable insight for my project. Great find!
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 27 ·
Replies
27
Views
6K
Replies
1
Views
4K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 21 ·
Replies
21
Views
13K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
Replies
1
Views
2K
  • · Replies 39 ·
2
Replies
39
Views
6K