Name the mystery part!! - RC Groups
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Jan 18, 2006, 03:08 AM
Custom Course Wrecker..

Name the mystery part!!

A quiz for the more experienced members.This part is in the wiring in the Darby.I'm curious to know if it has anything to do with sensing heat, or is it some electronic part. It has velcro on the back, as if it was going to be attached to something else. With the serated shape of the top fins...they look like they could be meant to fit inbetween the fins on the esc.

What I'm getting at is: could this be a heat sensor that mounts on top of the heat sincs on my esc's and controls the pump to circulate water through the system to cool them? If I ever figure this out....I'll probably have replaced the esc's by then. The right one STILL overheats, even with a fan, when running single stick helm. They BOTH get warm when running independant helm control.

If anyone knows, please let me know.

Scott (STILL lost in the wiring...)
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Jan 18, 2006, 03:27 AM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Actually what that looks like is a home made BEC, with a couple of capacitors to limit voltage spikes. As it reduces the voltage, say down to 3-4.8 or 5 volts, the excess voltage is dumped as heat.

If it has input and output wires, try putting in 6 then 12 volts and see what comes out. Actually, what is the numbers on the transistor. That would probably tell us something...

I had some wiring diagrams I corrected somewhere...yup
This might help decipher what it does.
Last edited by Umi_Ryuzuki; Jan 18, 2006 at 03:36 AM.
Jan 18, 2006, 03:29 AM
Registered User
Looks like a simple voltage regulator to me.
Probably to provide a stabilised 5V supply from the main battery.
I can't quite read the numbers of the device, if you can tell me those I'll be better able to help.
Jan 18, 2006, 07:07 AM
Mmm, tugs...
patmat2350's Avatar
I see a 5.0 on there, it's a 5v regulator.

Pat Matthews
Jan 18, 2006, 09:56 AM
Boats on the brain!!
green-boat's Avatar
It looks like a 6.0v voltage regulator, probably used a BEC. The Velcro is used to mount it where ever you like. I wouldn't mount it to the ESC's heat sink, any additional heat on it could damage it.
Jan 18, 2006, 10:28 AM
CG Bob's Avatar
It is a SubTech Battery Eliminator/Voltage Regulator; used to drop 12 VDC (main motor)down to 5VDC (for radio system). It's a very common item in model subs. I'vew got one in my 1:72 scale USS SKIPJACK. I'll post a picture when I get back from the boat show.
Last edited by CG Bob; Jan 18, 2006 at 11:17 PM.
Jan 18, 2006, 11:20 AM
Registered User
Yep, it's a voltage regulator (BEC). Only thing I'd add is to NOT use the fins for mounting, they get hot, won't 'help' whatever you stick them in.
- 'Doc
Jan 18, 2006, 11:34 AM
Custom Course Wrecker..
Thanxs for the replies, folks!!!!

Jan 18, 2006, 12:37 PM
Registered User
Here is a typcial circuit diagram for it

One thing to be careful with is not to allow the heatsink to touch anything metalic or any loose wires just in case the mica insulating is faulty or has been omitted!
Jan 22, 2006, 11:34 PM
Registered User

Name the Mystery Part!!

Hi All,

Steve P. here. The part is a LM317T 3 Terminal Variable Voltage Regulator. It is manufactured by many companies and has been around for many years. It is easy to design and work with. You can look for it in Ask Jeeves or Google.

The site I looked it up under is: The 117 is similar to the 317. Schematics can be found under: "Application Notes".

Theres are other regulators such as the 7805 which is a fixed regulator that is even easier to use.

Be careful of the wiring schematic because if wired incorrectly, you will see more than just an operating temperature rise!! It has a high input voltage of 37 VDC and a low output voltage of 1.2VDC. The high current is rated at 1.5 amps, which operates better, (and longer) with a good heat sink.

A typical application might be to use a 12 volt battery and to run 4.8 volt servos, etc. A higher output current can be arrived at by using an output transistor such as a 2055.

Again, observe the wiring schematic(s) carefully. The model (house, car, etc.) you save, may be your own. If you are not sure, ask someone! The National site above is one of many. If interested, you may purchase the LM317T at Radio Shack and other suppliers. Retail price is about $3.00.

Good luck, and keep the keel side wet.

Steve P.

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