Electronic advice... 4.3v, 4.8v, 6v, 12v from 7.4

[Cryofix]

I am confused to say the least, I took electronics in High school but that was back in 89 so needles to say I dont remember the ins and outs.

I have an A640 4.3v input, an RX that can use 4.8-6v (has to power 2 servos and rx), and the wireless downlink, my current 2.4 supports 4-6V but I am looking into the 900 mHz which is 12 volts.

What is need is a device to distribute power to all of these off 1 7.4 volt li-poly source.

can anyone point me in a direction to a premade setup for variable voltage regs? maybe a link to schematics, or some pointer's on what to search for


Thanks,
Ed

[miami6]

Ed i dont think you can get 12 volts for your down link form a 7.4 volts lipo /li ion battery


You need to start with a 3s lipo packs or 3s li ion pack 3s 3 cells at 4.2 volts per cell charged

To get the voltage to run the 12v downlink --- then you can use a BEC like the align or the Koolsystems BEC to bring it down to 6or 5.4 volts to run the rest of the gear

[Cryofix]

http://www.rc-cam.com/dc-dc.htm

shows a boost switching regulator that converts mah x 2 to upconvert voltage
Several years ago the RC-Cam site introduced the PT5041N DC-DC Boost Switching VReg as an efficient way to obtain 12VDC from a 4-cell (4.8V) NiCD/NiMH pack. The PT5041 accepts 4.7VDC to 11.0V on its input. In return, it will provide up to 1 amp at 12.0VDC on its output. Weight is just a few grams.

Miami6 I thought the same thing until I came across this site

[panomaniac]

Maybe this can help you if I understud you correctly:
http://www.rangevideo.com/de.html

http://www.dimensionengineering.com/images/products/DE-SWADJ.jpg

[AZ ChopperCam]

I run everything from 6v. My A640 handles it fine, and my 600mw and 500mw Black Widow downlinks run from 5-7v.

[MarkD]

One of these will do job

http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294564331&name=SiteStandard&forwardingPage=line&R=0299575&callingPage=/jsp/browse/browse.jsp&BV_SessionID=@@@@1310952134.1178384043@@@@&BV_EngineID=cccdaddklghfllkcefeceeldgondhgj.0&cacheID=uknetscape

The equivalent should be available in the USA

PS: Sorry for the long link - Radio Spares seems to like them :arggg:

[Efliernz]

For an easy way to drop voltage in steps, add a diode (1N7004 etc) at approx 0.7v per diode (in series). While not perfect (if obtaining a dc-dc device is difficult) it is simple. The Align UBEC uses this system for "digital servos".

[MarkD]

Just to clarify are we talking about

1 - getting a 12v supply from 7.4V or
2 - getting a 4.8V supply from 7.4V

[Cryofix]

Upconverting 7.4 to 12 V for a possible future 900 MhZ Wireless downlink.

as of right now I can run everything off 7.4 volt lipo, but in the future i would like ot keep the 7.4 in order to keep the weight down.

[MarkD]

One of those DC-DC Pump Convertors should do the job in the link above then