While a 6V battery may work, I would be concerned with voltage regulation. If the data logger is a true 5V device, a simple series diode may not keep the supply within acceptable limits over the typical range of battery voltage from full charge to discharge. An analog LDO regulator would be a better choice than a diode.
However, a 12V battery supply would, according to the original post, also allow the receiver to be powered from one source. Jack K8ZOA On 1/6/2012 12:49 PM, David Gilbert wrote: > > Why not just use a 6 volt motorcycle battery (two or three in parallel > if necessary) with a series diode? The total weight isn't going to be > any different no matter what you do ... one battery for everything or > separate batteries for receiver and data logging. AH capacity is AH > capacity. The efficiency would probably be above 85% if a diode rated > for a couple of amps was used, assuming a Vf around 0.7 volts, and it > would be tough to beat for quiet. > > Dave AB7E > > > > On 1/6/2012 9:34 AM, Jack Smith wrote: >> There are quite a few simple switching regulator chips for 12V --> 5V, >> requiring only a handful of parts to make a complete switching >> converter. For example, National Semiconductor (now TI after the recent >> purchase) LM2591HVT-5.0/NOPB. Stocked by Mouser and DigiKey at about $6. >> This series is available in a through hole 4-pin TO-220 style device so >> breadboarding up a one-off power supply isn't too difficult. >> >> With careful attention to detail, bypassing and shielding it should be >> possible to build a quiet 5V, 1A supply around these parts. It can be >> small enough to fit into a 2"x2"x1" Hammond die cast enclosure, and you >> can use feedthrough caps for input and output, along with some internal >> LC filtering. >> >> Still, 5V at 700 mA with a switching regulator and a 12V battery >> (assuming 100% efficiency which isn't possible of course) the setup will >> require 300mA from the battery. For 100 hours of operation, you're >> looking at a 30 Ah battery requirement. While a battery will output more >> Ah with a 100 hour discharge cycle, it's not that much more. A 35Ah >> sealed 12V gel-cel type lead acid battery will run you about $100. >> >> For serious long duration battery operation, I would look for a more >> thrifty data logger. >> >> Jack K8ZOA >> >> >> On 1/6/2012 10:10 AM, John Gibson wrote: >>> Dear Elecraft list members, >>> >>> The recent thread on noisy switching power supplies leads me to a related >>> question. My son n8fyk, who teaches radio astronomy, has set up a project >>> with his students. They are using a 15m direct-conversion Radio Jove >>> receiver in the field to monitor radio emissions from Jupiter, the sun, and >>> the galaxy. The receiver operates from 12V, which is readily supplied by a >>> portable utility 12V battery pack. Their problem is powering their data >>> recorder, which needs about 5V at 0.7A. >>> >>> The data recorder is designed to operate from three internal AA alkaline >>> cells, but these give a limited run time. My son would like to be able to >>> leave the receiver and recorder for unattended operation for several days >>> at a time. >>> >>> One solution would be to use a 12V-to-5V power converter between the 12V >>> battery and the data recorder. For long battery life, it would be nice to >>> have the efficiency of a switching converter. Such a converter would have >>> to be RF-quiet, so as not to interfere with their weak-signal reception. >>> >>> I will be interested to hear what list members recommend. >>> >>> Thank you and 73, >>> >>> John, no8v > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
