12 volt internal rail

[aokman]

Hi all,

Just wanted to see if anyone else has modded their phantoms to tap 12v internally for running extra lights etc? Finally got the cover off mine after fighting with it for ages and started hunting around on the board, found a few places of interest but the labelled one seems to be the prime candidate however I have no idea how big the supply capacity is of this rail.

I considered a separate regulator tapped to the 15v feed from the battery however space is tight so I won't bother.

 

[FRBEAR]

Have you considered the big wire marked VCC on the left? You could put a Zener diode in line to drop the battery voltage down to the voltage desired. 15 volt battery, 3 V Zener = 12 V

 

[Tony Perry]

Id be more tempted to attach a voltage regulator to the battery input line. Depending on the regulator you could get all the current you'd need for any lights. Seems like that would be the easiest to undo also.

 

[aokman]

Have you considered the big wire marked VCC on the left? You could put a Zener diode in line to drop the battery voltage down to the voltage desired. 15 volt battery, 3 V Zener = 12 V

Good call, I didn't consider the voltage drop of a zener. Seems like it would work fine.

I went out hunting today and found a 190 lumen light with a 12-30VDC input. Might see if that will fit aswell, getting a regulator in there is a tight fit...

 

[Sevyn13]

Have you considered the big wire marked VCC on the left? You could put a Zener diode in line to drop the battery voltage down to the voltage desired. 15 volt battery, 3 V Zener = 12 V

Could you explain how to use a zener diode?

 

[AerialTouch]

Put the zener diode in series with the load and it should drop the voltage based on it's rating. (3v = 3volt drop)

Not that an LED is that sensitive to input voltage, but I would recommend a regulator over a zener to maintain better control of the voltage. Also be mindful of the current rating of the zener or regulator. If undersized, the magic smoke gets out and they stop working.

Given the high current capacity of the flight battery, I would also consider fusing the circuit to avoid a battery "incident" because of a short.


Sent from my iPad using PhantomPilots

 

[N017RW]

I would suggest a little Google research to learn in more detail how to implement them.
As mentioned above there is risk to damaging other components if improperly used.

 

[peter west nz]

I just tap off the main battery connector, without opening the case. You can get at the rear of it through the battery hole. Need to be good at soldering in confined places though. Current was a bit high with the 12v leds I was using, so I just put 4 x 1n4007 diodes in series - drops voltage by about 2.8v. If you want to use a regulator, you need to use a low drop out regulator. Normal ones such as 7812 need at least 3v higher than the output voltage, so they will lose it as the battery gets down. Even better, use a switchmode one, they are much more efficient.

 

[peter west nz]

Here is a suitable ldo regulator. Just needs a 22u cap on the output to 0v.
TEXAS INSTRUMENTS LM2940CT-12/NOPB. LDO VOLTAGE REGULATOR, 12V, 1A, TO-220.