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>> Home > Forum > Hobby Chit Chat! > Exciters/transducers
Exciters/transducers
(1249 views)
Author Message
NPJ
(Fleet Admiral!)





Forum Posts: 140
30th Jul 2018 12:13  
>> Permalink
mdlbt.com/44422

Is it right that you must place these Units above the waterline?

Also is it worth thickening the boat hull, at point of contact, to improve sound?

By the way, how do you make new 'Posts' always appear on the top of the list?

I bet RN Munich will be on to the one!
NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
30th Jul 2018 12:41  
>> Permalink
mdlbt.com/44426

Hi Neil, am I getting too predictable!? 😲
Transducers; yes, above the waterline as much as possible, unless you want to stick your ears underwater to hear it! Thickening the hull might just improve the bass and dampen the treble by shifting the resonant frequency of the hull down a bit.

'New Posts'; just hit the 'Refresh' button of your browser.
Ciao, Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
30th Jul 2018 14:33  
>> Permalink
mdlbt.com/44431

Thanks for that Doug. Was wondering about using 4 small ones spread about so could keep them high up. Would that be series or parallel to match a digisound unit?

Re 'Posts', I mean in the 'threads' new first. I have pressed the 'oldest first button' to no effect...................

Cheers.
NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
31st Jul 2018 15:03  
>> Permalink
mdlbt.com/44460

Hi Neil (or Neville?),
There are two issues with using four.
1) Since these 4 Ohm transducers work by bringing the surface they are mounted on to move like a speaker cone, there may be no advantage. In fact two on the same surface may create waves through the hull side that partially cancel each other and thus reduce the volume. True, they may sometimes combine as well. This effect will happen in specific frequency ranges depending on the stiffness of the hull.
Put one each side on the largest open area available as we discussed for the tug. Cheaper anyway 😉

2) Speaker impedance and the minimum that the amplifier can handle.
Check the Digisound specs Output Impedance to see if the amp can handle 4 Ohms or only 8 Ohms, which is the case for all sound modules I have seen or used.
As with your tug, two x 4 Ohm transducers in series gives 8 Ohms for max volume from an 8 Ohm amp output. Four in series would give 16 Ohms which would significantly reduce the volume produced.
Two x 4 Ohms in parallel though only presents 2 Ohms to the amp, which highly likely will blow the output transistors 😡 All four in parallel would be only 1 Ohm which would most definitely produce the 'magic smoke' 😭

Don't forget to put a little enclosure around the back of the transducer after it's stuck to the hull.
Cheers, Doug 😎
PS What 'Oldest First' button? I don't see one. If you are using the dumbphone App I can't help you. I DON'T!


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
2nd Aug 2018 23:01  
>> Permalink
mdlbt.com/44571

Thanks . The Richardson seemed to work fine with two, but much smaller boat.

I will take your advice and use two with enclosures.

I am using the Digisound Unit LM for sounds.

I have been looking through other threads. Do you agree that balance point for such as this 'tender' should be 2/3rds fore'd?

Also thinking of putting oilers for the drive shafts. Sensible with this size or not necessary?

You see I always have something for you!

All the best.

NPJ (Neville) but I answer to many things...............


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
2nd Aug 2018 23:19  
>> Permalink
mdlbt.com/44573

Hi Neville, where did I get Neil from?😲
Sorry can't help with balance point cos I don't know the boat.
All I do is trim out in the 'Domestic Test Tank' for best balance along the waterline. Cheers, Doug 😎
PS I forgot the oilers😲 I only bother to fit them in fast boats with high revving brushless, like I did with my Sea Scout renovation, see 'Jessica' blog.
For scale 'plodders' I don't usually bother. Just pull the shaft now n again and use a plastic syringe to inject some oil or Teflon grease.


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
3rd Aug 2018 00:00  
>> Permalink
mdlbt.com/44578

I would have thought you need the thinnest part of the hull for best vibration?👍

RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
3rd Aug 2018 00:05  
>> Permalink
mdlbt.com/44580

Agreed John, 👍
That's why I said probably all thickening would do is alter the tone.
Ciao, Doug


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
3rd Aug 2018 01:45  
>> Permalink
mdlbt.com/44584

See here Doug-----https://www.banggood.com/MINIQ-BG-5156E-Bench-Drill-Stand-71...
£46 odd USA Warehouse get it while it's hot as they say £19 P&P

RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
3rd Aug 2018 08:00  
>> Permalink
mdlbt.com/44585

Thanks John👍
Hmm! Those guys should clean the bench once in a while😲 before they injure themselves on the swarf! Or it gets somewhere it shouldn't in the machinery or electrics😡
That cross bed looks exactly like the one on my Proxxon mini miller!
Doug


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
3rd Aug 2018 08:33  
>> Permalink
mdlbt.com/44586

OK folks decision taken. Two 2" ones on thinnest bit high as possible and enclosed.

No oilers for now.

Thanks.
NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
3rd Aug 2018 10:16  
>> Permalink
mdlbt.com/44587

Hi Neville,
The largest open area between bulkheads or stiffeners is the main criterion, not nessa-celery the thickness!
BTW: What is the vessel anyway??
Doug


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
3rd Aug 2018 11:55  
>> Permalink
mdlbt.com/44588

It is this one Doug with these Motors.

no oilers and the two transducers on order.

All the best.
NPJ


Attached Files - Click To View Large


NPJ
onetenor
(Fleet Admiral!)





Forum Posts: 405
3rd Aug 2018 21:52  
>> Permalink
mdlbt.com/44592

They could use the swarf for scouring rusty metal👍

RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
3rd Aug 2018 21:56  
>> Permalink
mdlbt.com/44593

Ouch! 😡


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
3rd Aug 2018 23:29  
>> Permalink
mdlbt.com/44605

No ouch with gloves on Doug. Works a treat on shafts etc. Shifts the scale alright. Follow up with wire wool for a nice shine. BTW your French let you down. No x in bureau unless more than one. Sorry. Same with gateau. Ciao signor😁

NPJ
(Fleet Admiral!)





Forum Posts: 140
4th Aug 2018 09:44  
>> Permalink
mdlbt.com/44616

Ooops, must have moved into the Open University Thread........


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
4th Aug 2018 10:38  
>> Permalink
mdlbt.com/44617

Learn something new every day😉
Quick, enrol for your PhD in Model Shipbuilding,
ONLY A FEW PLACES LEFT!! 😁


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
4th Aug 2018 13:46  
>> Permalink
mdlbt.com/44622

Yes, so where dop I place my 'thesis'?

Not really a build blog so where should it go?

re earlier post. I would like to have the most recent posts in each 'thread' or whatever at the top of the presentation rather than the bottom.

How do I achieve that O' fount of all knowledge.................?

NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
4th Aug 2018 13:52  
>> Permalink
mdlbt.com/44623

Ah! You mean the Forum Threads not the Build Blogs.
Strangely blogs are as you want but Threads the other way up.
Never bothered me. I just press Ctrl and Pos1 to go to the top or Ctrl and End to go to the bottom of either.
Theses as Threads in the appropriate Forum topic please 😁
Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
4th Aug 2018 14:23  
>> Permalink
mdlbt.com/44625

Still cannot make newest on top happen but not to worry can cope.

Hey I see I am an Admiral now. Must be in Gilbert & Sullivan...........

BTW, ordered exciters from Mr. RC so can compare a little with those in the Richardson.
All the best.

NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
4th Aug 2018 15:02  
>> Permalink
mdlbt.com/44627

Hi Neville, you can't get newest on top in threads, but at least you can jump to the newest or the start!
Congrats on the promotion👍
Welcome aboard HMS Pinafore Admiral😉


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
4th Aug 2018 19:23  
>> Permalink
mdlbt.com/44630

And our ship she is a beauty.Eh! Doug saw this IF you need one--- https://www.banggood.com/2_5-Inch-Plat-Nose-Pliers-Aluminum-...
Also a couple more drills as well and this-------ccccchttps://www.banggood.com/BG6350-Multifunction-Drill-Vise-Fix...
But I think you already have one don't you. Look here ---https://www.google.co.uk/maps/place/7+The+Grove,+Prestatyn+L...

NPJ
(Fleet Admiral!)





Forum Posts: 140
4th Aug 2018 23:00  
>> Permalink
mdlbt.com/44636

Thank you Doug. I still have to salute you of course................
I have been reading some of your 'builds/ refurbs.

Picked a lot up from those.

I assume 'Build Chit Chat' is the right place for the RAF Tender work.

Also, as a result of having issues with 'scale' sizes, I now have some extra bits for the Richardson!

I am sure Admirals should not have issues understanding 'scale', but I struggle to make sense of some of the proportions of deck furniture for example and windows.............

Going to bed now to sleep on it.

Cheers
NPJ.


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
4th Aug 2018 23:12  
>> Permalink
mdlbt.com/44638

What was the old rule_
'If it moves - salute it.
If it don't move - PAINT it'!
G'night All,
Doug😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
4th Aug 2018 23:14  
>> Permalink
mdlbt.com/44639

HI John
So I wasn't far off with the 'boat transporter' was I!? 😁
Thanks for the tool links, You're right - I have those already, for my mini miller and the drill press.
Cheers, Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
5th Aug 2018 14:23  
>> Permalink
mdlbt.com/44651

These look useful Doug.I just ordered some----https://www.manomano.co.uk/miscellaneous-multi-tool-accessor... Also nice cross slide on Bang good but you have one--or two don't you. Boat transporter was the nice silver saloon on my drive which I stupidly let go to scrap😡😡😡😡😡😡😭👍. We need a thumbs down emoticon here.Hasta la vista senor. P.S. Why aren't keyboards standardised. For instance no END button on mine or accent tabs. Like cedillas etc.

RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
5th Aug 2018 14:54  
>> Permalink
mdlbt.com/44652

Thanks John, have a good set set of milling, routing, grinding, drilling, finishing, polishing tools for my Dremel and Proxxon.
Thinks! We should continue this in the Hobby Chit Chat section; thread 'Useful Tools'? before we overload Neville's thread too much!
Will reply re emoticon and keyboard in 'Anything else'!
Cheers, Doug

BTW: This link should work folks!
https://www.manomano.co.uk/miscellaneous-multi-tool-accessor...


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
onetenor
(Fleet Admiral!)





Forum Posts: 405
9th Aug 2018 20:35  
>> Permalink
mdlbt.com/44894

I got some of the rubber polishing buffs. They work well so I ordered some more.They wear down quickly though. Wore one out doing most of one engine.👍 Oops wrong thread.

NPJ
(Fleet Admiral!)





Forum Posts: 140
10th Aug 2018 14:41  
>> Permalink
mdlbt.com/44913

With regard to the transducers.

I did not cover the backs of the ones in the Richardson Tug, but will do with these.

Do the covers sit on the transducer ring or pass over the lot and stick to the hull?

NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
10th Aug 2018 15:38  
>> Permalink
mdlbt.com/44918

Arternoon Neville,
If you're happy with the way they work in the Richardson then leave the covers off.
If you want to experiment fit covers around the transducer but not touching it, analogous to speaker cabinets😉 For simplicity it can be square/cubic in form, with the back about 1cm from the back of the transducer. Glue some thin, fairly dense foam rubber in the back.
With luck this will concentrate more noise outside where you want it.
The flyboys cut a hole in the fuselage and cover it with gauze, just like a Hi-Fi box. NOT very practicable for a boat😲
Cheers, Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
NPJ
(Fleet Admiral!)





Forum Posts: 140
10th Aug 2018 15:45  
>> Permalink
mdlbt.com/44919

Great stuff. I can do that whilst waiting for the sealer to come.

Do I need to isolate (dense foam) the container from the hull or can I stick it directly on?

NPJ


NPJ
RNinMunich
(Fleet Admiral!)





Forum Posts: 2312
10th Aug 2018 16:18  
>> Permalink
mdlbt.com/44921

A thin dense foam might be good, in case sticking it hard to the hull dampens the propagation along the hull side.
If that does seem to happen leave it off, but bench tests are not much good for this sort of thing, only the acid test on the wet stuff is really useful😉
Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Grant me the Serenity to accept things I can't change, - the Courage to change things that I can,
and the Wisdom to know the difference!
pmdevlin
(Fleet Admiral!)





Forum Posts: 364
16th Sep 2018 08:06  
>> Permalink
mdlbt.com/46234

Im not on here that much, so a little late picking this up. Are you talking about TT25 transducers like the ones Mrrcsound sell/ I suppose they all work the same, I've used these a lot, in planes mostly, and experimented with boats, so can offer some hands on advice.
Firstly, you don't cut any holes to let sound out, as this isn't how they work. Its all about the vibrations. The centre ring is epoxied (that's the best way, they have to be permanent, but with some teasing they can be removed it required, rather than cyno) to the surface, which obviously needs to be flat. The thinner the material, the more sound, but its marginal, as the thinner you go, the less bass, or deeper tones. With planes, the best material by far is the epo foam, so when mounting into a ply or balsa plane they work best going to foam, then the ply, and the same will apply for a boat. 2-3mm is generally the optimum thickness. Remember, the area is going to vibrate, so use an area that can do this, the sides of a hull are ideal. The back of the transducers get hot, so don't cover the back, the heat has to dissipate and once secure, make sure the unit can move in and out, its easy to drip glue in the wrong place and the whole thing gets stuck, it wont vibrate now, so won't do the job.
Also, its worth epoxying the transducer to 2mm foam, epo that the ready to fly planes works best, its close density, the stuff that packs white goods is poor as its a more open density and falls apart. Once you have this, you can move it around by just holding it against the hull to see where the best sound is.

All this is relevant to the Mrrcsound transducers, I use a number of his sound units, so cant really comment on what you are using as I cant find that info on this thread (did a man read!)
Here are a couple of my models to give you an idea👍

https://www.youtube.com/watch?v=jXFvrkDl7ow&t=207s

https://www.youtube.com/watch?v=_OITvPabFHY&t=165s

so these are all Mrrcsound units, and both have two tt25 transducers either side ogf the hull and fuselage.

With the Mrrcsound systems, you can use two tt25, if you want an additional two, then an aux amp is required
hope that helps!
Paul


Attached Files - Click To View Large

NPJ
(Fleet Admiral!)





Forum Posts: 140
16th Sep 2018 09:10  
>> Permalink
mdlbt.com/46237

Great stuff. Really useful.
Interesting that they do not want boxing in.
It is the mrrc ones that I intend to use on the Launch. Have Dayton ones on the tug.
Away at the moment but will check out you YouTube stuff when back.
Are you saying more open foam/polystyrene works better than the more dense stuff?
Cheers.
NPJ


NPJ
pmdevlin
(Fleet Admiral!)





Forum Posts: 364
16th Sep 2018 19:22  
>> Permalink
mdlbt.com/46254

More dense really. The epo foam used on the ready to fly rc planes is ideal. I used Depron on the fire boat it’s the stuff used to insulate flooring. It was ok but a bit brittle.