Bluetooth

[Noob]

I have bluetooth headset (battery powered) and i want to dismantle and you it as a receiver for my speaker (which is already working with own power), but i want to remove the battery so i can plug it in for longer use, can i use the mobile charger which 5v volts output and directly connect to battery terminals? If not how can i reduce the voltage? The battery was rated 3.7v

[shteii01]

You can use two diodes in series with 5 volt supply.  Each diode is about 0.65 volts, two of them in series is 1.3 volts.  When the two diodes are in series with 5 volt supply you will have 5-0.65-0.65=3.7 volts.

By the way.  Are you fan of Red Green Show?

[Noob]

What kind of diode?
Thanks!
*no, not fan of red green show..*

[Buriedcode]

Any power silicon diode (not schottky) rated for 1A will do.   If its just for the bluetooth module, then it'll probably draw 40mA max.  Even so, 1A silicon diodes are cheap as anything, like the ubiquitous 1N4001/4. So although a 100mA diode like the 1N4148 will probably do, two 1N4001's would be my choice.

[Noob]

Thanks guys!! 😃😃😃

[Noob]

Will it be safe for the receiver? Because when i google on converting 5v to 3.7, they have complicated circuits.. thanks!

[Buriedcode]

Depends on what you mean by 'reciever'.  A small bluetooth module will draw, at most, 40mA, so two diodes - each having a forward voltage drop of ~ 0.65 would give 5 - 0.65 - 0.65 = 3.7V.

Some probably use a linear regulator to get 3.7V out of 5V, as the output voltage is...well.. regulated.  But for low currents, not really needed, as the bluetooth module is designed to run off a Lithium polymer cell, which can be anywhere between 3.3 and 4.2V.

If you're powering other things form this 3.7V then you may require a different scheme. 

What exactly are you trying to achieve? schematics/block diagrams welcome

[Noob]

Maybe i am the stupid person here but i just want to make sure..  what i want to do i remove the bluetooth receiver from the headset change its power source from battery to a wall mount charger and connect the output to a selfpowered speaker..
(Same as the bluetooth music reciever but i just want to recycle my headset)..

And one more thing if i remove the battery and directly connect the usb charger to charging port of b.t reciever, will it run?

Thanks

[janekm]

Depends on what you mean by 'reciever'.  A small bluetooth module will draw, at most, 40mA, so two diodes - each having a forward voltage drop of ~ 0.65 would give 5 - 0.65 - 0.65 = 3.7V.

Some probably use a linear regulator to get 3.7V out of 5V, as the output voltage is...well.. regulated.  But for low currents, not really needed, as the bluetooth module is designed to run off a Lithium polymer cell, which can be anywhere between 3.3 and 4.2V.

If you're powering other things form this 3.7V then you may require a different scheme. 

What exactly are you trying to achieve? schematics/block diagrams welcome

Why wouldn't you use a regulator? Bog-standard LDO? Costs less than two diodes, and diodes are not a reliable component for voltage drop at low currents.

[testmode]

How about this? >>

5V-40V to 3.7V 1A DC DC Step-Down Buck Converter Module

$2.69 and free shipping.  Plus, it accepts a wide input voltage range so you can practically use any wall wart adapter you might have lying around.

http://www.ebay.com/itm/5V-40V-to-3-7V-1A-DC-DC-Step-Down-Buck-Converter-Module-for-18650-li-ion-battery-/282257512841