| Electronics > Projects, Designs, and Technical Stuff |
| Piezo Sounders - mounting under a decal? |
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| max_torque:
I have a project where we would like a haptic feedback beyond that provided by the actual buttons and indicator leds on the HMI. An existing product uses pcb mounted buzzers, pointing out sideways, through gore vents, to provide a small range of "beeps and chimes" to indicate operational events. What i'd like to do is to simplify (and potentially reduce cost too) that solution, ie to provide a relatively loud (>85dB) sound indicator to the user, but the solution must be waterproof and pass some stringent EMC requirements too (hence the previous buzzers being inside the box). To add a further complication, ideally i'd like a solution with the lowest "stack" height possible! (the buzzer solution, vent and hole is "tall") My current best solution, but with completely unproven provenance is to use one (or more) flat piezo sounders like this: Which i plan to mount in a shallow recess machined into the top of the alluminium case of the HMI, and to cover that sounder with the decal that acts as the waterproofing agent for the LEDs/ Buttons. This leads to two main questions: 1) How much damping, and hence attenuation in volume will the decal introduce? (the answer of course is "what's the decal like?" :-DD ) There maybe ways to reduce damping through thickness / mass optimisation. The Sounders are typically at around 1khz, so the mass of the decal could well be significant? 2) How to electrically connect to the Piezo? I want to avoid soldering, wires or connectors. Current plan is to use two spring contacts, soldered to the pcb which sits under the top of the HMI and holds the switches / LEDs. Those contacts could push up through the lid, and make contact with the back of the sounder? something like these: Production volumes are low (say 1k units PA) but it needs to be easy and simple to assemble. Anyone have any relevant experience or knowledge in this area? :scared: |
| Richard Crowley:
We have seen teardowns on EEV and other YouTube channels of gadgets with piezo sounders where the sounder was glued into the case and contact was made from the PC board with simple gold-plated solid spring-wire bent into the appropriate shape. You don't need much current-carrying capacity, so those spring terminals in your photo seem like huge overkill. |
| Berni:
These piezo discs are actually designed to be glued onto something. Often mounting them tightly to a thin material makes them louder because the flat object it is mounted to starts to flex along with it, this produces sound from a larger surface area. |
| Wendy_Preston:
Hi all, just to confirm that the picture is of our Spring Contacts here at Harwin. These ones are our Antenna contacts - they might look big in the picture, but they are pretty small in reality. The heights range from 1.23 to 2.00mm high for the upper row, and 2mm to 5mm for the lower row. You can see the whole range of spring contacts in our Catalog section: https://cdn.harwin.com/pdfs/Harwin_PC_EMC_Shielding_Spring_Contacts.pdf I'm not familiar enough with your application to confirm they'd be the exact solution you require, but if you need miniature spring contacts, these are a good choice. Stocked in depth in our authorised distributor network, and you can also request samples from our website https://www.harwin.com. Need any help, feel free to contact me on technical@harwin.com. |
| Berni:
Ah didn't know Harwin had a applications engineer on here. Some might say this is spam, but i think this is a great way for manufacturers to interact on the forums. A user has a need for a thing and they suggest there solution. Rather than buying ad space or starting threads filled with just pure marketing bullshit. |
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