Engineering a sealed speaker into IP67 Encosure

[thomaskuhn]

I am currently working to improve a product of ours that is a rugged, embedded, man wearable computer enclosure. Our customer would like to implement an audible alarm or better yet, a speaker to play prerecorded audible warnings.

The current design is a simple 3" x 6" two piece machined aluminum case which is currently packed pretty tight to fit much additional hardware. Most wall thicknesses are 0.07" In looking into solutions, two items came to to front, first being a audible transducer made by NXT. This would simply be adhered to the inside lid, and is designed to use the surface itself as a speaker surface. This would eliminate any additional openings, but might not perform as desired. The second product from Murata is a super thin Piezo speaker VSLBG1914E1400-T0. It is ultra thin but seems to be dificult to mount externally or in a recess. The third option is to have a opening in the case in which to surface mount a traditional speaker or Piezo. The issue with this is concern over MIL-STD-810 and MIL-STD-461 EMI issues that have to be dealt with with an additional opening.

Could anybody give some good design ideas or products to get audio on this system? In particular, sealing a audio speaker to IP67, case holes and mounting for a Murata type product, externally?

 

[IRstuff]

> EMI can be dealt with by using a grill, which is almost a given, since you need finger protection anyway.

> You could potentially stay with your first option, by thinning down the casing above the speaker to allow it to vibration sympathetically

> However, IP67 requires survival through immersion as well as dustproofing, so any openings are going to be problematic

You've not stated what your loudness requirement is. That'll have the biggest impact on what you can do with your system.

TTFN

FAQ731-376

 

[thomaskuhn]

Thanks for the input.

As for loudness, anywhere from 85db+.

 

[IRstuff]

An alternative version of the hogged-out chassis is to braze or solder a diaphragm over an opening in the chassis

TTFN

FAQ731-376

 

[thomaskuhn]

Thanks,

I will look into this also.

 

[MintJulep]

There are several hand-held marine VHF radios that equivalently waterproof.

Go to the local marine store, buy a few examples, take them apart and see how they do it.