Using a common power supply for 2 gadgets?

[squishyalt]

I have 2 small devices that have their own power supplies. I want to combine the two boards into a single housing/device.

One of the devices uses a 3.7 volt 130mAh battery for power. The second uses 2 AAA batteries (1.5 volts each). What would be the best way to use only one power supply to power them both (if that is possible)?

I do understand that using a single power supply would drop the amount of time that the 2 devices could operate as compared to each using its own power supply. That is acceptable.

 

[Lynx_Arc]

what are the devices?

 

[squishyalt]

I am just a beginner at electronics, so I am wondering why it matters.

If one device requires 3.7 volts DC and the other requires 3 volts DC, what about the devices could alter the power requirements?

I am trying to learn as I go....

 

[Lynx_Arc]

I am just a beginner at electronics, so I am wondering why it matters.

If one device requires 3.7 volts DC and the other requires 3 volts DC, what about the devices could alter the power requirements?

I am trying to learn as I go....

Some devices are more sensitive to voltage levels that others and because of that you would need to know the operating range of both devices before you could consider such a device as it may be simple to make it or harder. For example, if the 3.7v device would run off 2.5v then you could run both items off of 2AAs, if the 2AA device would run well at 4v then you could run both off the 3.7v supply. Without knowing what voltage range both devices are designed to operate in you cannot easily design something to supply both of them.
Typical devices running off 2AA run from 2.2-3.4v, while those running off lithium ion or 3.7v may run from 2.5 to 4.2v well.

 

[2filthy3]

Would help to know what you are powering... and the 3.0V battery powered devices current draw.

3 rechargeable Nimh aaa's would also give 3.6v.
Or an rcr123a would get back some runtime.

The most simple way could possibly the to use the 3.7v supply to run the 3.7v device, and put the 3v device in parallel with it, with the addition of a single diode in series with only the 3v device, as a silicon diode will drop 0.7v (more likely 0.5/0.6), allowing the 3.0v device to receive the correct voltage.

 

[Lynx_Arc]

Would help to know what you are powering... and the 3.0V battery powered devices current draw.

3 rechargeable Nimh aaa's would also give 3.6v.
Or an rcr123a would get back some runtime.

The most simple way could possibly the to use the 3.7v supply to run the 3.7v device, and put the 3v device in parallel with it, with the addition of a single diode in series with only the 3v device, as a silicon diode will drop 0.7v (more likely 0.5/0.6), allowing the 3.0v device to receive the correct voltage.

actually if the 3.7v is a lithium ion battery they can come off the charger at 4.2v and nimh cells can be in excess of 1.4v off the charger too. When you are dealing with power you need to know the maxiumums supplied to it and accepted by the device without damage and minimums it will operate properly at also as cutoff voltages can be a problem for some batteries as devices designed only for alkalines can by stupidly made to stop working below 1.3v which is where a nimh battery still has plenty of power left.