Will some electronics wizz build and sell this please?

shmoo

shmoo

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When we sail we often play music really load through the cockpit speakers. (Before anyone gets on their high horse, only when no one else in earshot). Trouble is we can't hear the VHF (which shares the cockpit speakers, but lacks the power to compete)

We need a device to mute the opera and allow us to hear the VHF when the VHF is actually talking.

Years ago I would have taken up soldering iron and veroboard... I suspect this is not an unusual problem.

device.JPG


1) Should work at speaker power/impedance levels, say 3 ohm, 25W
2) Usually (with power on) pass entertainment input to speaker output
3) If any audio is detected on VHF input switch both speakers to that instead, with fast attack and slow decay (say 5 s)
4) Right-side failure - i.e. power off should leave VHF connected to speakers
5) Packaged for marine interior environment

My guess is these could be built for about £5 and I would happily pay in region of £30-40. Would others find this useful? Will someone build one and offer it for sale?
 
Funnily enough I thought about a gadget exactly like this years ago. I'm an electronics engineer and businessman so understand all too well how expensive it is to develop a product for small scale production and then make a profit. Bottom line is, what would someone pay for one of these without thinking too long about it followed by how big is the market, you'd be lucky to sell more than a few hundred here I would have thought, and that is if the price were say £15 or less. Someone out there is probably making and selling them already anyway (I'm a very negative person!)
 
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how expensive it is to develop a product for small scale production and then make a profit.


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I think I already knew that, but was still hoping it wasn't the case... bah!
 
Like seadog I am also an electroincs engineer, mainly nowadays desgning emebedded microprocessor systems. What you are asking for is not feasible and I also doubt there is a market for it.
Probably the easiest way to do something similar is to use a car radio as a lot of people do, many have an input for mobile phones and do exactly what you need, mute on input of phone, by connecting the vhf output to the phone input on the radio you will get more or less what you ask for. As for vhf function when off, a small relay could be used to switch the vhf to a single speaker in the cockpit when the audio system is off. you could switch to the existing stereo speaker when off by the relay, but I would prefer a load applied during relay switching, not too dificult though.
Joe.
 
I've got something which sounds similar to your description in my car stereo.... when I'm listening to the radio or to a cd, if my sat nav wants to talk to me, it mutes the radio or cd and it also does the same when traffic news i've preselected comes on..... then a friend who has his mobile phone hands free connected to a similar system also has his music automatically muted when a call comes in on the mobile.

So clearly, we the technology and the knowhow already exists commercially?
 
Some motorcyclists use a system that allows them to listen to music, talk to each other, rider to pillion or rider to rider using PMR radios and listen to the instructions from a talking GPS, and even talk on the mobile phone. It does pretty much what you describe, in that the various inputs are in a hierarchy of precedence so GPS info takes priority over music for example. Autocom is the best known make. They are designed to run off 12V but only to drive headphones so the output might not be sufficient for boaty purposes as it stands. Might be worth talking to them though. http://www.autocom.co.uk/
 
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not feasible


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I would think is was quite feasible. A diode and an appropriate time constant RC on the input from VHF extension speaker leads would give a steady few tens of mV a few hertz after some audio appeared. With amplification and a little logic this signal could be used to switch a pair of reed relays to change input from Entertainment to VHF. If one wanted load applied during switching, with two reeds relays per wire it would be possible to arrange make-before-break. However this not really needed since both inputs are from optional extension speakers and are happy to run into no load.

Right-side failure characteristic is just a matter of making sure the relays rest, unenergized, in the right position.

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and I also doubt there is a market for it.


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I fear you may be right on this point so I may have to find the soldering iron after all.
 
Hi Schmoo, I meant not feasible as a saleable project for small scale production, as said, the costs of production are not cheap, PCB, Populating, adding a case, mounting, waterproofing or weather proofing, a bit of style for the punters, io connectors, labelling, instructions and packaging never mind marketting and support make it a no go.
As for actually making one for yourself, yes, perfectly feasible... /forums/images/graemlins/wink.gif
Joe
 
Wow, thanks for all that input.

The mixer has exactly the functionality, with priority inputs and all, but at microphone levels so unsuitable for retrofitting to marine VHF extension speakers. It also looks very professional (read expensive)

The mobile phone/car radio thing suffers from being too integrated. My car does all that but doesn't really have a separate "radio" - its all smeared over the dashboard. Even the old-fashioned mobile phone on a cradle muting the car radio depends on the phone putting out a "I have a call" signal, which my VHF is not about to do!

The motorcycle headset comms controller looks like a bet: one of them has VOX on the input so I will look further at that. Headphone level is not too much of a problem since we put the audio through a boy-racer car type amp* on the way to the cockpit speakers. I did say in the original post we had it on loud!

* takes input at speaker levels/impedance and give output as speaker impedance but more of it.
 
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not feasible as a saleable project


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Thanks for clarification. As you realized, I thought you meant infeasible from engineering point of view. If there is a wrong end to the stick, I will grab it...Sorry!
 
I've done exactly what you are trying to do.

Picked up one of these for aboyut £25-30 on ebay

Does exactly what you are after I think - draws very little power - and lets you control how long a slilence you need to drop back from VHF to music (actually more important than I thought - as if this is set too short the VHF tends to be clipped and you miss the start of communications - not sure how much this is the actual sound and how much the human brain)

http://www.smarthome.com/9725780.html

Used it this summer on all our offshore passages - and it worked a treat so far. Smallish and easy to fit
 
Already available in some car radios which also play your mobile calls - music is muted when the phone rings. I wonder if you could adapt one of these for your boat... probably a couple of hundred quid for the unit though.
 
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