Scale working Radar

[remondo]

I would like to have a working radar on my model customs boat, does anyone have a scratch built working radar they could post, or does anyone know of a kit available to do this?

[CG Bob]

Loyalhanna Dockyard (http://www.loyalhannadockyard.com/) is carrying the JJC Electronics line of products, whic includes a radar unit. The radar unit is a new item and doesn't appear on the JJC (http://www.jjc-electronics.com/media/JJCCatalogueJAN2005.pdf) web site yet. In the past, I've stripped down an old servo and used the guts to spin the radar antenna.

[Massey]

Towboat Joe did a working radar on one of his Towboats. He used a pully under the roof of the pilothouse to make this happen. Here is a link to the pics.

http://www.towboatjoe.com/american_viking.htm

The picture of this is about 1/2 way down the page.

Massey

[towboatjoe]

I did the pulley system to make one geared motor operate two radars. If you don't have a detailed pilot house it becomes pretty easy to make a working radar. Basically all you need is a small geared motor clost to around 27 rpm and wire it to turn clockwise. The simplest one is a a pole mounted radar. All you need to do then is run a rod up the middle to mount the revolving antenna to. I'll take a photo of the radars on the roof I've got built now and upload it.

[towboatjoe]

Here's a simple radar I'm building on the viking. Framing legs are plastic angle and cross bracing is strip plastic. The platform is a square piece of sheet plastic and the radar body is a piece of balsa wood. I've got a center tube made of brass for my shaft support and a brass rod going down to the pulley that is belt driven under the roof. Just make a scale 6' or 8' antenna and drill a hole in the center for the shaft to fit and it's ready to go.

[remondo]

I never thought of a pulley. My radar will be mounted on top of a mast array so I will need a shaft to run straight up inside the middle of it, maybe with a pulley system on top powering 2 radars which would look good. What motor and batteries will you use towboatjoe?

[towboatjoe]

I mounted a small 3 volt geared motor horzionally against the bottom of the guest cabins. It turns around 35 rpm. I used some old gears I had to make a 90 degree verticle shaft that goes up through the control arm of the hand operated spot light. It enabled me to gear it down a little more to get around 27 rpm that I wanted for the radar antenna. Believe me, I used to spend a lot of time sitting and counting the rotations when nothing else was going on at the river.

You can get really nice geared motors that turn anywhere from 24 to 31 rpm at Jameco, but they run anywhere from $16 to $25. I prefer to shop around the online electronic surplus stores and find them aroud $5. places like All Electronics, Edmund Scientific, etc. All you have to do is use a search engine for electronic surplus store or even D C gearhead motor.

[DanL]

Use a servo, modified to turn 360degrees. Put a small resistor in the power lead to slow the servo to desired RPM. Did this on my tug - direct drive and easy to do.

[Roger in France]

As you are in the UK have a look at www.members.aol.com/actionkit/ This guy is a small one man band supplying electricals for boats. He is very helpful and has a radar kit, quite cheap and good. I have used 2 of them.

Roger in France.

[Boatfox]

Use a servo, modified to turn 360degrees. Put a small resistor in the power lead to slow the servo to desired RPM. Did this on my tug - direct drive and easy to do.
Did that on one boat...only ran it off of 1 battery cell. At 1.5 volt it swings very realistically.

[patmat2350]

Hint- If you have multiple radars, use slightly different size pulleys so that they don't rotate at the same speed. Your eye can really pick out when they rotate in lock-step, while the different speeds are very noticable and convincing.

Pat M

[P_J_Glor]

Generally when you have multiple radars, you have different functions. This is particularly true of Military ships. A surface search radar has the longest range an will turn slower because it takes longer for the reflected beam to come back from distant targets. Air search and navigational radars must be updated more quickly for accuracy and turn much faster. Fire control radars generally do not rotate as they are aimed at a target, so they should be couple with a weapon such as a gun mount or turret.

I used a set-up very similar to Towboat Joe's on a trawler with a large gear underneath the pilot house and a shaft going up along the rear bulkhead of the pilothouse to the roof above. It is powered by a very cheap "toy" motor and powered by a single AA sized battery.

I like the idea of pulleys, because you could make your own custom diameters with circles of different thicknesses of plastic and a piece of tubing for a bearing.

Pete G.

[Greg Hiltz]

Robbe has 3 scales of different radars, and Graupner also has 2, which you can cut the array to the length desired (from scale 2ft to 8ft). Robbe also makes this super precise and small(think size of your thumbnail squared), geared 200,500,and 1000:1. The 500:1 at 6v gives a realistic rotation approx. 20rpm.
I've powered many over the years, some were nery simple, a bicycle spoke shaft up through a pipe mount to the sweep array, a couple were similar except for an offset horizontal clock gear set to extend out on a bracket and hide the gear-train. The false ceiling with cassette-deck pullies and belts works well to hide the main shaft through the wheelhouse, and in a 45ft fish dragger built 1:16, I ran the gear-motor shaft up through a vertical stair hand-railing to a pulley drive in the ceiling at the center of the house, 1/16" shaft up through a (4"real)pipe mast, then used a dentist's drill 90deg angle drive tip running out a horizontal (3"real) pipe bracket to the radar mount, which required another 90deg.angle drive turned upward to turn the rasdar itself! I spent a week devising that system from soldered brass tubing. The dentist angle tips are chromed brass, which take solder well after filing off the plating. This model had large, almost 2"square windows, so the wheelhouse was well detailed inside. I had made the two radar monitors from maple, hollowed out inside to take a small bulb, set into epoxy with an actual radar screen image in the epoxy for the screen. I thought this was cool, until a friend who was an electronics whiz said he could duplicate the sweep-and fade look of an actual CRT screen in sync with the rotation!! A week later, he had this adjustable"self-unloading capacitor thingy"circuit board, which worked perfectly when timed up with the radar speed. The effect was great, along with the fibre-optics used for indicator lights on the radars,sounders, auto-pilot, loran, and VHF radios. The lighted, 1/2" working compass would catch people's eye when I waved a metal pen past it. There's no end to how far a guy can go when obsessed with super-detailing a large-scale model. I may dig out the photos someday and scan a few for the forum if anyone's interested.
-Greg

[remondo]

I have found a very small motor from a mini radio controlled car, would it work as a radar? I have a tiny gearbox which could be used to make it run at scale speed. Only thing is I don't know what voltage the motor is. there was a resistor in the circuit but I don't know anything about resistors. Anyone help me?

[patmat2350]

Don't confuse "small" with "appropriate"! The problem here is that smaller motors tend to run faster, so you could need even more gear reduction. Motors like this are often found in pagers/phones to drive the "buzzer" (an unbalanced weight). Likely runs ok on 3v.
Motors vary with windings, size, and applied voltage, but the little guys typically are happiest running 10-20,000 rpm. To get a 30 rpm radar, you'll need 300:1 to 600:1 reduction!

PM

[Ghost 2501]

remmy that is a bit on the small side!

[remondo]

hmmm. ah well itl b useful for something!

[SDJ]

you could try this site http://oldriverbillzumwalt.members.ktis.net/special_effects.htm loads of useful info.

[Jayshum]

Use a servo, modified to turn 360degrees. Put a small resistor in the power lead to slow the servo to desired RPM. Did this on my tug - direct drive and easy to do.

This is what is in my Amsterdam. Unfortunately I've no idea how the guy who built it managed to modify the servo, but I'd love to know now (my Southampton would look great with one).

[Umi_Ryuzuki]

Use a servo, modified to turn 360degrees. Put a small resistor in the power lead to slow the servo to desired RPM. Did this on my tug - direct drive and easy to do.



This is what is in my Amsterdam. Unfortunately I've no idea how the guy who built it managed to modify the servo, but I'd love to know now (my Southampton would look great with one).


You can try this...
http://www.rcgroups.com/forums/showpost.php?p=7130746&postcount=40
Just add the resistor to lower the voltage and rpm.
Heck, you don't even need the pot, or the signal wire for radar rotation.


Patmat also Shows how here, again, Just add the resistor to lower the voltage and rpm.
http://www.geocities.com/patsmodels/servo/