3.3v Power Supply Options - What's recommended?

The items shown above are part of a 5.8GHz video transmitter (#5) setup offered by Range Video.  All items are sold as individual items and like a big dummy I forgot to get Santa Clause order their powersupply (#4) when she placed her order for the transmitter. 

So the luck of the Irish kicks in and Mr. Murphy ordered their last Filtered Linear Power Supply and there's no telling when they will be back in stock.  So I'm on the hunt for another suitable power supply that will output the required 3.3v to run the transmitter and camera.  I've poked around and found that a lot of the setups used by fellow DIYDrones members have built in voltage regulators and are just attached to a lipo (typically 7.2v).

I have a few other projects in mind beyond the video transmitter for my Raven so getting a good lead on a good ps would be very nice to have.

I did manage to find several power supplies that may work but I'd like to know what more experienced tinkerers think.

#1

Breadboard Power Supply 5V/3.3V by Sparkfun

This one is intended to use a walwart in the recommended 7-9v range.  It outputs a selectable 5v or 3.3v but forgive the newb-ness, I'm not sure if I HAVE to use a walwart.  Wouldn't a 2 or 3 cell lipo do the DC trick just fine?

#2

DC-DC 12V to Dual output 5V / 3.3V LED Power module

This E-Bay special is pretty cheap and has free shipping.  It seems like it would do the job just fine and would not need to be converted to not being a plug in for a breadboard. But would a LED power module work for the above mentioned video transmitter?  Voltage is spot on to what I need but I'm unsure of the LED part of the description...  

#3 

You tell Me...  If all these finds are junk and you use something else, please let me know.  Also if you have a design I could build that would work too.

 

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Comment by Renato Aranghelovici on January 22, 2012 at 2:57am

I use this module for over one year simply connected directly to 1 lipo cell. Yes, directly !

No sensible overheating, even no heatsink or airflow.

Used in house for tests for many minutes without cooling.

The power is sensible bigger when fully charged, I estimate it at 300mW based on consumed current difference vs 3.6V

Comment by Owen McAree on January 22, 2012 at 5:07am

I have used these switching dc-dc converters for numerous projects. They are a little more expensive than linear regulators (like the ones in your post), but they take a very wide input voltage range (5-36V) and have a high current capacity (~1A) without generating any heat and they are considerably more efficient (98% vs about 75%). They come in various output configurations (the linked one is 3.3V as per your post), I have used the 5V variety connected directly to a 4 cell lipo (~15V) and never had any problems!

Obviously they don't come on breakout boards, but I tend to solder wires directly to the legs then cover the whole thing in hot glue to stop it fatiguing.


Moderator
Comment by Brian on January 22, 2012 at 10:12am

@ Renato - I have wondered about that, but also considered that I might need to supply power to other items at a higher voltage.  I'd like the ability to split the power source for multiple items with possibly different voltage requirements.  Per your comment though, seems like I can do some testing w/the 1 cell lipo.

@ Owen - So you use a bat, on pin is connected to the pos input, another is connected to pos output and the ground is common?  Could you post a small diagram or pic so I'm sure to understand this trick?  Dont want to burn anything up...


Moderator
Comment by Brian on January 22, 2012 at 10:23am

I have also found this power supply from sparkfun.  It also looks very promising. (link) This one has options for how power is connected and has an on/off plus dual voltage. This one is bigger than the other sparkfun unit but it is assembled.  Anyone use any of these?

Comment by Owen McAree on January 22, 2012 at 10:35am

Yea it is as simple as you said. The very last section of the datasheet has a diagram showing the pins. The middle pin (2) is a common ground, pin 1 (the one with the dot above it) is the input voltage (5-36V) and pin 3 is the regulated output (3.3V).

I will take a pic of one of our cables with one of these regulators in-line tomorrow.

I have experience with linear regulators (the type on the sparkfun boards) and wouldn't recommend them for high current or high step down ratios. But if your supply is less than ~12V and your current draw is less than an amp I'd say they are absolutely fine


Moderator
Comment by Brian on January 22, 2012 at 11:28am

Owen - Thanks for the help.  I'm sure that others have similar questions. This does seem like a very simple way to do it.  Does this work to power multiple devices (w/same power requirements) or is it for one device only?  

With the inline device I could do a cable with multiple devices (3.3v, 5v, 9v, 12v) and end up with more power options than the unit from Range Video, which only allows one voltage at a time.  hmmm

Comment by Anish on January 22, 2012 at 12:58pm

@brian looks to me like a lm317 three pin voltage regulator chipset. as per specs it could support upto 1.5 a. The idea of mutliple outputs sounds interesting


Moderator
Comment by Mark Harrison on January 23, 2012 at 1:07pm
Comment by Anish on January 23, 2012 at 1:55pm

@mark wouldnt be suprised, its like a well known recipe for cooking. Tried tested cheap lm317 :)


Moderator
Comment by Mark Harrison on January 23, 2012 at 5:21pm

@Anish, does this look like a reasonable design for the lm317?  I think I would want to replace the pot with a resistor of the appropriate value.

http://www.ladyada.net/library/equipt/diypsupp.html

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