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Old Apr 26, 2009, 07:42 PM
Jason
super_nova's Avatar
United States, SC, Rock Hill
Joined Jun 2004
878 Posts
Question
Can I run a 12v power supply instead of a battery in my radio for simulator usage?

I asked this over in the DIY forum, but I figure this is a good place for it too. Here's the situation: I've been using my rc simulator alot more lately with some friends. Problem is we use up the battery and then have to wait for a recharge before we can continue or actually go fly the real planes. This happen the other day where a perfect flying evening came up after we had been flying the simulator during the windy afternoon and used up the battery....

What I'd like to do is setup some sort of power supply so that I can just take out the battery while flying the simulator, and use the battery just for flying my planes. I've got an old hobbico 12volt wall cube charger with alligator clips for charging 12volt field box batteries. If I were to attach a futaba plug, and plug it into my Futaba 7C radio, would that work (I'm talking about removing the battery and connecting the power source to the battery plug, not to the charge port which I know won't work)?

Connected directly to my volt meter I'm reading about 10.9volts from the power supply. From my viewpoint, I can either plug in the 8cell battery that gives around 11 volts peak charged, or plug in this wall plug thats giving me just under 11volts and I would think my radio would operate the same. However, I'm no expert on this and before I go playing with the power source for my expensive radio, I'd rather get some other opinions.
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Old Apr 26, 2009, 08:15 PM
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Joined Jun 2008
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...YES you can

I thought the same the last year.
Here is my mod & let me know if you need help.

http://www.runryder.com/helicopter/t...ghlight=PC+12V
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Old Apr 26, 2009, 10:04 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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There's a lot of interesting stuff in that thread but it takes a bit of wading through.

One thing to notice is that Andika is using the PC power supply as the source of 12 volts and then dropping that voltage by using a couple of diodes. This is a much more stable power source than the wall wart you are proposing to use.

Another thing is that you can't just plug the power supply into the charge jack of the transmitter. Doing so automatically disconnects the battery from the radio, and this is a feature that must be retained (the charger can have high voltage spikes that won't hurt the battery but might damage the radio). So you will have to feed the radio through a connector to the circuit board.
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Old Apr 26, 2009, 10:26 PM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
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Quote:
Originally Posted by Daedalus66
There's a lot of interesting stuff in that thread but it takes a bit of wading through.

One thing to notice is that Andika is using the PC power supply as the source of 12 volts and then dropping that voltage by using a couple of diodes. This is a much more stable power source than the wall wart you are proposing to use.

Another thing is that you can't just plug the power supply into the charge jack of the transmitter. Doing so automatically disconnects the battery from the radio, and this is a feature that must be retained (the charger can have high voltage spikes that won't hurt the battery but might damage the radio). So you will have to feed the radio through a connector to the circuit board.
Ya I mentioned that I was going to connect it through the battery connector, not the charging port, because I know that won't work. I guess the wall plug I have could fluctuate in voltage as a load is applied? Is that what you mean but less stable. I can't imagine the radio draws very much.

I took a look at the thread Andika posted. It is interesting and looks like it wouldn't be too difficult to setup. That would work well for my home where I can setup a dedicated plug to my computer's power supply. However, I also use the simulator with a laptop and with coworkers in our board room . So I need a more flexible solution.

The second to last post in that thread does mention that removing the crystal will give much better battery life, so maybe I'll try that first.
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Old Apr 26, 2009, 10:36 PM
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Raleigh, NC
Joined Apr 2007
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You should be very careful using cheap wall-wart type supplies because they are unfiltered and have no spike protection.

If you can't convert one of the PC power supplies then buy a good regulated power supply from Radio Shack or some other electronics supplier.

Bill
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Old Apr 27, 2009, 01:36 AM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
28,396 Posts
A 12V wall wart usually pumps out *way* more than 12V when it's lightly loaded.

You can pick up a cheap computer power supply that'll give you
many useful fully regulated voltages.
This one is $13 bucks
http://www.tigerdirect.com/applicati...5&sku=D15-1013
My dad followed the directions here
http://www.wikihow.com/Convert-a-Com...b-Power-Supply
to make this:
http://www.raccoonhouse.com/Images/Power_Supply.jpg
He uses it to power the 12V stereo in his work van when it's running on A/C.

I'm less motivated and just have an old Dell power supply cobbled together
but it gets the job done.

Can pull 10 amps through the +12V circuit.
That's enough to power just about any typical 12V Lipo or A123 charger
at a pretty high load.

ian
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Old Apr 27, 2009, 08:14 AM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
878 Posts
Ok thanks for the info guys. I will forgo the wall plug power supply. And carting around a pc power supply is a bit more than I want to do for now. I'll try running the simulator without the crystal in the radio and see how well that works, and maybe I'll pick up a second battery or even a lipol radio battery.
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Old Apr 27, 2009, 12:29 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
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Quote:
Originally Posted by super_nova
I'll try running the simulator without the crystal in the radio and see how well that works, and maybe I'll pick up a second battery or even a lipol radio battery.
Shutting down the RF section should roughly double the run time I would think.

As for LiPos in the transmitter, that's a whole other story debated at length in this forum! I'm a fan of Sanyo Eneloop NiMH cells for this kind of application -- no LiPo problems, fast charge if you want (1 hour) and very low discharge between sessions.
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Old Apr 27, 2009, 12:48 PM
Will fly for food
Maryland
Joined Sep 2004
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What radio?

Most radios will turn on, with the RF section off, if you just plug the sim cable into the trainer port. You leave the power switch OFF.
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Old Apr 27, 2009, 02:35 PM
59 years of RC flying
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Canada, ON, Ottawa
Joined Feb 2006
16,185 Posts
Quote:
Originally Posted by Pinecone
Most radios will turn on, with the RF section off, if you just plug the sim cable into the trainer port. You leave the power switch OFF.
This is certainly how it works with JR/Spektrum. I thought it might be different with Futaba.
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Old Apr 27, 2009, 04:04 PM
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Joined Aug 2002
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Quote:
Originally Posted by Daedalus66
This is certainly how it works with JR/Spektrum. I thought it might be different with Futaba.
Correct Hitec & Futaba simulator cable plugs do bypass the RF section of those TX.
Pins 4&5 are shorted out (both 6 pin DIN plug & Square mini plug types).
However, to lessen battery drain and prevent extraneous RF. in case of error or incorrect cable, it is prudent to always remove crystal or module.
Further information under:
"Buddy Boxes. Servo Leads. Flight Simulator & Interface." at:
Alan's Hobby, Model & RC FAQ Web Links

Regards
Alan T.
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Old Apr 27, 2009, 06:13 PM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
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My radio is a Futaba 7C 72mhz. I'm using it with the simulator Aerofly Pro Deluxe, and the radio has to be powered on.
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