Hi
I recently completed another project but run into another funny problem. This portable bluetooth speaker is DC adapter powered and the supply to the bluetooth is through a 7805 regulator then passes through a B0505S power isolater. Now whenever the bluetooth is connected via my smartphone it will show only 30% battery instead of 100% battery using my previous method separated power transformer method. The B0505S i've build didnt use any of the input and output filter caps ... just direct input and output connected to the Bluetooth module ... Any idea what is causing it? Thanks
I recently completed another project but run into another funny problem. This portable bluetooth speaker is DC adapter powered and the supply to the bluetooth is through a 7805 regulator then passes through a B0505S power isolater. Now whenever the bluetooth is connected via my smartphone it will show only 30% battery instead of 100% battery using my previous method separated power transformer method. The B0505S i've build didnt use any of the input and output filter caps ... just direct input and output connected to the Bluetooth module ... Any idea what is causing it? Thanks
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Hi , B0505 is unregulated isolated converter . Its output voltage depends on load current. Did you tried measure voltage coming into B0505 and what is out of it ? Maybe you need higher power module . Or use regulated one . What is input voltage to 7805 regulator?
i've input 19.5V into the 7805 regulator ... since the whole unit is powered using laptop adapter ... another thing is it a must to use input and output caps for the B0505S module?
Probably bt module measures its supply voltage , and its not fully 5v after b0505 . You have put regulator 7805 before b0505 module ,so if your bt module increase load at some moment ,voltage drops (unregulated). More proper way would be measure current ,drawn by your bt module actually ,and purchase isolated regulated (stabilysed output voltage) dc dc converter , input 12-24v , output 5v regulated ,capable supply required current. Then you don't need 7805 at all.
u mean the DC to DC converter?
https://shopee.com.my/LM2596-Adjust...9?sp_atk=062f160f-e219-4460-84e4-cfcb3eab8abc
i dont know this might work or not
https://shopee.com.my/LM2596-Adjust...9?sp_atk=062f160f-e219-4460-84e4-cfcb3eab8abc
i dont know this might work or not
Nope ,this one is not isolated. It will work partially , it don't removes ground loop , so you may hear beeps and noise from common ground to speaker amplifier.
The 'percentage remaining' is based on the voltage presented to the BT module. Slightly lower voltage will lower the '%' indicator.
I've built a very similar setup but ended up using a buck converter because dropping that much voltage through a 7805 is not very efficient.
My advice is to go 19v -> Buck -> B0505S -> BT module. Adjust the voltage at the buck converter to give a steady 5V before connecting to the DC-DC or you will probably kill it.
Those BT modules put lots of noise on the ground, but I've found that using the DC-DC is a good way to tame it.
Another tip is to follow the datasheet for the B0505S with respect to capacitors. They specify the external components for good reason..
Good luck with your project!
I've built a very similar setup but ended up using a buck converter because dropping that much voltage through a 7805 is not very efficient.
My advice is to go 19v -> Buck -> B0505S -> BT module. Adjust the voltage at the buck converter to give a steady 5V before connecting to the DC-DC or you will probably kill it.
Those BT modules put lots of noise on the ground, but I've found that using the DC-DC is a good way to tame it.
Another tip is to follow the datasheet for the B0505S with respect to capacitors. They specify the external components for good reason..
Good luck with your project!
Measure voltage first ,what is coming into b0505 and what is getting bt module input ,maybe too much drop on wires.
Yes, use a buck converter instead of the LM7805. Dropping 14v (19v-5v) across the 7805 is going to waste a lot of power in the form of heat. A buck converter is much more efficient at around 70-90% compared to 50% or less.
A simple lm2596 module can be had for a couple of dollars.
A simple lm2596 module can be had for a couple of dollars.