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Old Sep 05, 2006, 05:21 PM
If you cant find it Build it!
LONGBIKE's Avatar
NEAR ST. LOUIS ILL. SIDE
Joined Jan 2006
1,504 Posts
Help!
voltage regulator

Does anybody know how to build or where to buy a voltage regulator that will take down from a 12 volt system to a 5 to 8 volt range?
I want to run my receiver off the motor battery, the reciever is a BEC type and can handle a 8 volt system as per manual.
My boat top "TITANIC" is a little hard to get off and on to keep charging the radio nicads.

longbike
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Old Sep 05, 2006, 05:47 PM
Drydock Captian
Massey's Avatar
Spanaway, WA
Joined Jul 2006
1,438 Posts
does the ESC drop the voltage going into the reciever at all? if the ESC will drop the input voltage to 8 V or so then you will not need a regualtor. If you do need a regulator then check out Mack Products they have a few different types.

Massey
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Old Sep 05, 2006, 05:48 PM
3 Blades to the Wind
Shaun Hendricks's Avatar
Atascadero, California, United States
Joined Oct 2004
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You can just buy an external BEC. Most receivers will run up at much higher voltages if you turn off their internal BEC's. There are plenty of BEC's that are made for high voltage inputs. Essentially they have the voltage reduction circuits in them and can handle much higher servo drain than receiver type BEC's.

That is the quick and easy route... but I'm sure there are off the shelf voltage regulators, it's a pretty simple electronics circuit. I have no idea where to get them for the hobby though. Most use the external BEC route.

Smart BEC

Hobby Electronics BEC
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Old Sep 05, 2006, 08:14 PM
Give the dog a bone
Boatfox's Avatar
USA, NV, Las Vegas
Joined Aug 2005
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Go to your favorite web based electronics provider and look for Voltage regulator. 5 volt and 6 volt are the common ones, but anything is available. Usually good for 1 Amp. Parts = two caps, a regulator chip and get as fancy as you want. Here is one I just made.
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Old Sep 05, 2006, 08:54 PM
If you cant find it Build it!
LONGBIKE's Avatar
NEAR ST. LOUIS ILL. SIDE
Joined Jan 2006
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Massey, No Im useing a vantec speed cont. and they dont have that option.

Shaun, I did find some of those but their mainly for the nicad packs that are around 7.0 volts.

Boatfox, that looks just like what I need can you by chance draw up a schematic and the parts you used? I would really love to learn how to make one of these.
I did look up a elecronics site to find this and didnt have any luck finding one in this range I need.

Thanks guys for your help!
longbike
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Old Sep 05, 2006, 09:02 PM
Boats on the brain!!
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Arnold, Mo.
Joined Jul 2005
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You can use an LM317, that would give a variable regulator. http://www.national.com/ds/LM/LM117.pdf Otherwise a 7805 would give you 5 volts or a 7806 would give you a 6 volt output.
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Old Sep 05, 2006, 09:16 PM
Give the dog a bone
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USA, NV, Las Vegas
Joined Aug 2005
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Jameco's 7805

Radio shack's 7805

Basic voltage regulator stuff with some circuits. Click me
The idea is to figure out what you want at the end and modify the basic cicuit to suit your needs.
#1 on/off switch?
2 easy disconnect from boat?
3 fused? or not
4 how big a package (how much space can you afford)
5 connections? umbilical cord to battery and to RX

etc etc etc.
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Old Sep 05, 2006, 09:32 PM
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Here we go.... simple.
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Old Sep 06, 2006, 06:13 AM
If you cant find it Build it!
LONGBIKE's Avatar
NEAR ST. LOUIS ILL. SIDE
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I tried to use one of those 7805 voltage regulators just by itself and nothing happened.No servo movement or anything.
But I will try this setup you got here boatfox it looks very simple This is just what I needed Thank you a bunch, You must be an electricion! I wish I could understand all this electronic stuff I would love to build things but for some reasond it just doesnt click in my mind to under stand it all and I have been to all kinds of schools or training for my job as a car dealership tech.

Thanks guys
jeff
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Old Sep 06, 2006, 09:03 AM
Give the dog a bone
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USA, NV, Las Vegas
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Quote:
Originally Posted by LONGBIKE
Thank you a bunch, You must be an electricion! I wish I could understand all this electronic stuff I would love to build things but for some reasond it just doesnt click in my mind to under stand it all and I have been to all kinds of schools or training for my job as a car dealership tech.

Thanks guys
jeff
Hah HA! I have fooled another one. I wish I understood more, but I try my best. This is probably the easiest circuit you will ever build. I've done other projects and you are right...some of us have trouble bending our brains around the pictures and parts. The easiest thing to do is to give in and purchase a nice soldering station, get the parts, and start simple and work up. I think the best thing I ever did was to buy a nice controlled solder station so I would have to fight that bit.
Funny you had issues with the v-reg...Make a big ugly one first and once you get the hang of it you can start to shrink the package and make it all smaller.
Worst case post pics and let us know...we can help you out. The plane side of the forum/site has all kinds of ideas for V-reg circuits. Most go a different route due to lipo batts and different requirements, but this circuit (7805) is a tried and true working setup for us boaters.
Good luck.
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Old Sep 06, 2006, 11:23 AM
3 Blades to the Wind
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Atascadero, California, United States
Joined Oct 2004
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Longbike... both those BEC's will handle up to 30 volts. They are a switching style so they are efficient throughout the entire voltage range. The circuits being shown do generate significant heat (wasted energy). Then again, that's a drawback of voltage regulators over switching power supplies. In the end, it's only a little reduced run-time, no biggie. If you want to build one yourself, go for it, it's a learning experience. Just remember: DON'T let the magic smoke out!

I'm not sure what receiver you are using so I don't know what it's maximum voltage capacity is with the internal BEC turned off. All mine are rated up to 20-30 volts with the internal BEC off. I have one high power one but it's an expensive puppy... made for aircraft.
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Old Sep 06, 2006, 12:09 PM
太刀風
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United States, OR, Eugene
Joined Jan 2003
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I have been using a 7805 in reducing my 12 V source to 5.8V for some time now. I run combat R/C ships, so the demands on the system are severe. I place three of the 7805s in parellel and on a heat sink. I have had only one system fail and that was an occasion where I continued to fight the ship as she went under. The ship was recovered and returned to combat later that day.
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Old Sep 06, 2006, 01:59 PM
Registered User
Joined Dec 2004
3,698 Posts
MACK Products has carried their #L27 automatic intergrated control for years. It is rated to run from 6 to 36 volts DC input, and give 5 volts at one amp current output. It comes withn heatsink installed and is listed under the radio section of their web site,www.mackproductsrc.com.
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