DFARS to 24hr conversion?

[Hhabilis]

This may have been discussed somewhere, but I couldn't find it.

I have a VP2+ wireless and just purchased a DFARS from Davis.   I have AC with an unused weatherproof outlet for my pond pump 10 ft. from my station.

Can someone explain how I can power my FARS from the AC outlet to make it operate as a 24hr FARS?  Do I simply need a regulated AC-DC converter? What specs should it have? Can I simply ignore using the solar panel for the FARS?  A wiring diagram would be great if this is complicated.

 I'd appreciate any details anyone can provide.

[dalecoy]

Perhaps if you had searched?

http://www.wxforum.net/index.php?topic=5347.0

[jerryg]

I have converted several dfars to 24 hr. Since you have ac there it is easy. I took a cell phone wall wart which showed 3.7 volts dc out and used the cable that connects the solar panel to the fan by splicing the cable to the wall wart wire making sure the fan turned the right way before making it permanent. Looking down on the fan it should turn ccw so the air is pulled up from the bottom. I put a resistor in series with mine to get the voltage on the fan at 2 volts which is what it normally runs at. You can run higher voltage on it but i would think it would cut down on the life of the fan. At 2 volts mine has been doing just fine on readings comparing to the 24hr fars i have. Keep in mind the wall wart usually puts out alot more voltage than shown on the box, it is current dependent, the more current you pull the lower the voltage.

[Hhabilis]

Thanks Jerry
That was a helpful response. Nothing in the 2009 thread noted by Dalecoy made me feel confident.

[dalecoy]

Thanks Jerry
That was a helpful response. Nothing in the 2009 thread noted by Dalecoy made me feel confident.

Sorry that wasn't helpful.  Radio Shack (and others) sell regulated power supplies, which don't have the disadvantages of varying voltage with current drain, and don't require selecting a series resistor, and hacking a cell-phone charger. 

Of course, that's an individual choice.  I've only been using my Radio Shack supply with my DFARS for about 6 years.

[jerryg]

I agree with delcoy if you can buy one then that would be the best way to go. I have been in the radio business over 50 years and have alot of stuff out in my ham shack, and i never buy anything if i can scrounge it up and make it work lol. I would rather build it myself than buy it ready made. I looked at my local rs for a supply module but they did not have one in the low voltage range. They used to have one that was switchable from 3 to 6 to 9 to 12 volts but not anymore. It was a good wall wart to have with so many uses. I am glad to read that you have got such long run time on your fan, makes me feel better about mine lasting for awhile. I read Davis gave about 40,000 hrs on the fan at the low voltage use. Dalecoy did you measure the voltage on your fan with the supply you are using? Just wonder what it was as a future reference if i ever need to change mine out.

[moehoward4]

The latest from Radio Shack is pt#273-315. It is a universal (1.5 to 12 volt) adapter that has a 3v option, 300ma, for $21.49. They also have a straight 3v adapter, 700ma, for $15.29, but I think the ma rating may be too high for the Davis fan?? I am going to do this soon, just trying to figure out the best wire options and routes.        Jack

[jerryg]

That is pretty costly, i think i will just have to keep scrounging things up lol. Free is always better.

[moehoward4]

Yeah, I know, but some of us don't have a bucket or garage full of electronic parts, or the knowledge to use them............We do what we know.

[jerryg]

That is so true, i hate having my truck worked on and paying out the dough. When i was younger i did all the repairs myself but with these new cars you have to have it done . Just can not diy on alot of things these days.

[dalecoy]

. Dalecoy did you measure the voltage on your fan with the supply you are using? Just wonder what it was as a future reference if i ever need to change mine out.

The one that I have been using for many years is the Radio Shack part number 273-023, regulated, 3V output.  It actually measured 3.0 V when running the fan (and when not running it).

That part number is still available if you use eBay.  Current prices run $11 or so.

The "new" RS part number for the identical supply is Enercell™ 3V/700mA Regulated AC Adapter, part number 273-312.

[jerryg]

Thanks for the info Dalecoy, will keep that in mind. In case anyone is interested i have been comparing my 24hr against the converted dfars which are mounted near each other and i am surprised by the results so far. I just took a reading on them and the dfars was showing92.3 while the 24hr was showing 93.0. At night the two are never more than a tenth or so apart so the difference shows up when the sun comes up. I compare both of them to my dual louver stevenson screen with an aspirated sensor which showed 92.1. The converted dfars does a really good job.

[jerryg]

Dalecoy, i ordered one of those supplies off of ebay, real good price with free shipping. They had 3 left so i got one, i think i am going to convert my 24hr over to ac in the near future and eliminate the solar stuff.

[moehoward4]

I ordered this item#, 350573185832, from EBay on Wednesday. $6.98 plus $2.63 s/h for converting my DFARS to 24 HR. I got 40' of 18-2 wire (sprinkler control) from the local Home Depot, $11.20, and when the adapter gets here on 6/16, mine's going 24 HR. THANKS, dalecoy, for the push to look on EBay        Jack

[moehoward4]

One question for dalecoy    Using the 273-023 adapter with the Davis fan, what are you getting for service life from the fan? My first adapter(yes, I did order a second one) came today and I hooked it up to a home made R/S that has a Davis fan in it, and the fan really hums along. The second adapter will get installed in my ISS next week. Thanks        Jack

[dalecoy]

One question for dalecoy    Using the 273-023 adapter with the Davis fan, what are you getting for service life from the fan? My first adapter(yes, I did order a second one) came today and I hooked it up to a home made R/S that has a Davis fan in it, and the fan really hums along. The second adapter will get installed in my ISS next week. Thanks        Jack

I don't know.  It's still running after about 6 years.  YMMV, of course.

[moehoward4]

dalecoy, thanks for the reply. Maybe I won't have to buy replacement fans as often.         Jack

[duke666]

I've decided to convert my FARS too. I now have a 3 volt reg PSU here. But, I don't really want to cut the fan wire or the panel wire so does any one know what the 2 pin plug / socket is that's used to connect the fan to the panel so I can obtain a couple?

This way if the PSU ever goes down I can quickly convert back for a while.

Duke

[dalecoy]

I've decided to convert my FARS too. I now have a 3 volt reg PSU here. But, I don't really want to cut the fan wire or the panel wire so does any one know what the 2 pin plug / socket is that's used to connect the fan to the panel so I can obtain a couple?

This way if the PSU ever goes down I can quickly convert back for a while.

Duke

As I recall, I didn't exactly do that.  I used some small Molex connectors that I had around, cut the fan wire and put a pair of connectors inline, as well as putting one matching connector on the cable from the power supply.

[C5250]

But, I don't really want to cut the fan wire or the panel wire so does any one know what the 2 pin plug / socket is that's used to connect the fan to the panel so I can obtain a couple?

It's actually a 3 pin connector. The connector happens to be the same as what is used to connect 3 pin computer fans to a motherboard. I've seen extension cables and cables to adapt from the 3 pin fan connector to a 4 pin power connector for such, so that may be the easiest way to get what you want.

[moehoward4]

All I have done is cut the fan plug off close to the plug, stripped and twisted the 2 reds together, stripped the black and used 22-18 ga. male and female snap connectors accordingly. This allows you to make what ever 'repairs/replacements' easier. The cable from the solar panel to the the junction in the FARS is just going into spare parts....for now. It has finally cooled down enough here for me to go up and do the deal on my ISS tomorrow AM, I have everything(almost) pre-assembled ready to go.       Jack

[duke666]

Thanks for your replys guys.

Mine is definitely 2 pin not 3. I can't find 2 pin molex connectors over here so I'm going to order THESE which are 2 pin PC fan connectors and with a bit of luck, as mentioned, might even fit existing.

Duke

[C5250]

The solar panel connector is 2 pin, the fan connector is a 3 pin.

It looks like what you found should work, it's just a common 0.1" spacing pin thing.

[duke666]

Just checking, but while I'm up at the ISS today, any reason why I shouldn't join (parallel) the now redundant FARS solar panel with the ISS panel? May help in those dull winter months, (and summer months in the UK).

Duke

[moehoward4]

Duke    I can't answer that question.....toooo far beyond my know-how. I just left it there in case of failure.         Jack