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Resolved Resolved by Rich!

3.3V Regulator Question

I have a Bluetooth speaker that runs on a lipo 3.3v battery. do I need a 3.3v regulator to run this speaker off of ez-b power? if so, could you recommend one?(looking for a specific name)

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The device can probably work at 5v but if not here is a URL to a nice dc to dc unit that will regulate 9 to 40vdc down to 3.3vdc

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That's just the LDO, you'll need to make a circuit to use that one, personally I'd use a pre-made regulator over making one, you know it's going to work and generally the cost difference is minimal, throw in the time taken to make it and it probably works out better value to buy a pre-made one.

You'll save around $1 at most by building the circuit yourself, if it works right away. For me it's better value to by a DC-DC converter pre-made.


MOST regulator circuits only take a few parts 2 caps and regulator chip

Plus they work at very low drop out better then most dc-dc converters some will as low as 3.4 volts with 3.3 volts out. What is means is that you battery will last much longer.

Look at the 3 pin 3.3 volt LDO that EZB uses super simple only 3 pins ,input,output and ground ,cant get more easy then that.

Some at a 4th pin for shutdown if it does just ground it.


The dropout looks fairly good on that one at .5 volts at 1amp and your circuit will use may be less. PLUS should only need one cap at the output ,since the 5 volt regulator has one. Spec sheet tells how easy to wire it up and pinout.

Another item about using it very tiny size compare to DC-DC CONVERTERS


I'd tap into the 3.3v right on he EZ-B if it doesn't draw to much amp.

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The 3v3 on the EZ-B doesn't supply much at all, it doesn't provide enough to power the WiFi module I got for the EZ-B. But yes, try that first, it wont do any harm to throw a jumper from the 3v3 pin to the speaker.


I agree with RICH the 3.3 volts on board doesn't supply enough current for EZB and bluetooth ,plus it will get the regulator much more hotter then it is.

i THINK the bluetooth speaker draws at least 500 ma if not more.


REALLY depends if you want to build it or buy it,both will work THAT link that ROBOT-DOC gave is 9-35 volts in at 3.3 volts out,so will need to hook it up to a higher battery supply.

And at 9 volts when the battery goes down some i wounder will it still regulate,(like about 7 volts)


@PJ_DTECHY that one looks like it will work good.


only recommend because I am currently using 3 of them on my Robosapien project and it does the job well.


I found out i bought 5 of them at a very low price. whats good about the dc-dc converter is they are adjustable.

And in ebay search if you put in LM2596 you will see a lot of the same one at lower cost.


PJ also your robosapien project comming along real good,i stop on mine for awhile till i get parts in.


PJ, does the regulator you suggested come with the cable ends to? Or how do you connect them?


@robotmaker, I am in the process of moving into my condo, all project all temporarily cease. The only downfall of my project was waiting for part to come from China, I can share your pain.

@Technopro just do a quick search on Ebay for LM2596 or voltage regulator and choose the one that fit your need. They are less than $5 including shipping. I also use this one since it display the output voltage. most of them are like your h-bridge motor controller, can be solder or come with a cable.


Awesome solid information from Rich, PJ Robot-doc Lumpy and robotmaker! that info certainly helps me. thanks so much guys!:)


As @Rich mention, you can always design your own, more fun and you learn more by troubleshooting trough your errors. But at the same time, they are so cheap.


You can manually adjust it to fit what ever voltage you desire. Yes this will do.

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Where are you getting your 5V from? If you take it from the EZ-B make sure you don't cause brownouts. Any idea on the power usage of the speaker?

Also, a further thought, if it is charged via USB you can just modify a USB cable and power from 5V since USB is 5V. It may be worth looking at that method (like DJ's method for the camera)


I don't do that anymore. it kept causing my ez-b to overheat, if you remember. I would like to wire the speaker up this way.

Edit: Big correction, the speaker has a 3.7v 450mah battery.

it's a delicate speaker so I need to wire it up to the correct voltage. if I use the regulator I found, it wont cause the ez-b to overheat, right?(in theory)

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The EZ-B shouldn't overheat with any accessories attached unless there is a problem with the accessory itself. I suspect previously when your camera was causing the EZ-B to overheat that there was a short somewhere. Many others, including DJ have had no problems with that method.

LiPo batteries come in 3.7v denominations. But fully charged are 4.2v. 3.7v when you should charge. Under 3.0v and it's ruined. Under 3.5v and it's being damaged. So with that in mind you can use anything from 3.3v to 4.2v without it being a problem. 3.7v is ideal though, 4.2v wont kill it. You could get lucky and try a 5v supply but it's at your own risk.

If you use a regulator I would advise connecting it to the battery not the EZ-B. No chance of it doing anything to the EZ-B in that case.


ITS current that causes overheat ,but if the battery is 450 ma i would guess it draws 75 ma to 100 ma,so its a very little load on your EZB.

So you will not have a problem,i have a bluetooth speaker that uses USB input also,haven't had a chance to hook it up yet.


There is another problem if the speaker uses USB its not a good idea to ,use the 5 volt usb input. Reason is that you using a battery to charge a battery ,5 volt usb input charging 3.7 volt battery

So the solution is remove the battery and attach 2 wire to it from the regulator board and have the board adjusted at 3.7 .


I use two of those exact converters in my robot. They work great and are fully adjustable. I did, as Rich says, connect to the battery and not the EZ Board.

Good luck with your build!


I agree with @Rich & @Herr Ball, tap into the battery with the voltage regulator ( voltage converter), modify voltage as needed ( 3. 7v) and leave EZ-B alone.


I would say the say thing,no problems overheating or making the 5 volt regulator very hot if you tap in using the battery and might last longer.

Second i would remove the 3.7 volt battery you don't want to charge a battery with another battery.


Ok so I will go with connecting it to the battery direct and will set it up to allow 3.7-4v


4 volts might be to high voltage for that circuit,i would say 3.6 volts to 4.8 volts and mostly you check it under a load hope this helps you TECHNOPRO

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@robotmaker, 4 volts will not be too high, a 1s LiPo cell when fully charged has a voltage of 4.2 volts. 4.8 volts on the other hand would be too high, I assume a typo?

@Technopro, stick with your last thought, the 3.7v to 4v regulator. 3.8v is probably the best voltage to set it to since this is the "official" rating of a LiPo cell. Although a week since your post I assume you may have tried this already? Have you had any luck or any further problems?

Don't forget to mark this one as solved once it is solved:)


YES it was typo everyone makes mistakes


And since i know so much about batteries since work at a company that uses batteries and i run tests

RICH is correct on the official rating of the battery

BUT since the board is adjustable can set at 3.6 volts or 3.8 volts.

The old saying goes "better to be safe then sorry" so at 4 volt it may or may not hurt it

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@Technopro, did the answers provided solve this question? If so don't forget to close the topic. I'm sure @PJ would appreciate it (unless you believe someone else deserves the credit):)


Yes thanks everyone. This helped me understand a whole lot. I've come to the conclusion to just modify the board to move the charging port and make it possible to turn the speaker on and off and charge the same way it is right now. Later on I may go back to this and attempt it.

Everyone helped me out, and I thank everyone for that, but rich's responses answered the questions I had in the best understandable way. Thanks!