VHF Speaker Widget

[sam am I]

I have, as some here perhaps do, a VHF marine radio(mine probably older type then most) in my boat. And perhaps like mine, some are mounted permanent types that just have a single small'ish speaker internal to the unit's box.

Well, when running, I can't hear the thing worth a crap If I had too even though it's just inside the Cuddy. So beings I'm frugal, I had to fix the thing the other day(No xmit....bad solder joints in VCO) and noticed it has an external speaker plug and since I have just a simple AM/FM radio(no aux in) I though, if I could just wire that VHF's external speaker output signal via a jack it into the boats radio speakers, I could at least hear it.



So this thing is wired such that if you push the monetary switch, it cuts out the radio's speaker signal and latches the relay's such that the VHF's speaker signal is routed to both L & R(and remains on the little speaker as well) radio speaker's. If then the power to the VHF is cycled off, it reset's the relay's and returns to the radio signal.

The VHF audio driver IC needs to be capable of driving 4 ohms BTW if the radio's speakers are 8 ohms for example(as in my case). I'll snap a few photo's as built and post them, I just went to RS tonight and got some parts. I might see if I can get it in a small box, not sure, probably should.

Anyway, just an idea on a ride home from fishing the other day and though someone might have similar ear's and setup and could use something from this...........nothing earth shattering.

 

[alldodge]

Nice idea but I see two possible issues. Don't know if the VHF has enough power to drive both speakers. The impedance will go from 4 or 8 ohms to infinity and back, so what will happen to either of the radios final outputs. Why not just pick up a cheap CB external speaker and use it for the VHF.

 

[sam am I]

Good points, all.

Ya certainly gotta know if the VHF can drive down to 4 or whatever its lower will be .....Most manuals will state the minimum load, mine does. If not, as one possible workaround, a guy can t open it up and look up the spec of the IC or perhaps a second possible workaround would be to shoot a call/email the manu and ask.

As far as opening and closing to loads,(4,8 to infinity and back) good spot.....

Ever go to Best Buy, stand at the wall of red lit buttons of speaker/amp/head unit choices and switch between 11'teen different amps for one speaker? Same.

Then ya hear some kid switching them at 100 db? Same(albeit at 200 Watts, not nice/healthy to do to your stuff)...........But, its just relay's like this, but just a bigger matrix.

Some/most high end home/car amps also, you'll hear a relay switch in(and out if it detects DC or a short) the speak's w a relay. Ever turn on you home stereo and the G-kid's had the volume up to 100db the day before and after that 5 sec delay........HOLY S**T!!!, it blasts on when the unit switches on the speaker relay? Same

Typically, the driver IC here are in the 1, 5,10 watt range too, it's truly no different than say a flaky speaker wire opening and closing when ya hit a bump and the damn speaker is flaking on and off or a guy hooking up/testing his speak's with the unit on before hand and/or just turning on your stereo/radio on with no speakers attached or the Best Buy thing. Audio driver IC(or discrete designs) don't require a maximum load.

I could do the CB speaker and run a wire out the cuddy and set it on the dash, yes. Nother good point......but I'm bored

 

[alldodge]

......but I'm bored

Me to, it's raining here and I'm killing time on iboats

 

[UncleWillie]

I would eliminate the lower relay altogether.

A simple switch takes it place.
Switch ON sounds the VHF.
Switch OFF returns to the FM Radio without power cycling the VHF.

If you really want to get anal, use a SPDT Switch and Kill the Power to the FM at the same time you steal the speakers.

An Amplified Marine VHF Speaker is another option.

 

[sam am I]

I would eliminate the lower relay altogether.

A simple switch takes it place.
Switch ON sounds the VHF.
Switch OFF returns to the FM Radio without power cycling the VHF.

If you really want to get anal, use a SPDT Switch and Kill the Power to the FM at the same time you steal the speakers.

An Amplified Marine VHF Speaker is another option.

Hmmmmm, good point. Cycling the power to VHF to go back to radio sig seems silly huh?. Maybe I was thinking(it was an 45 min run back to the slip, I had a lot of time) that since I have it's power switch(typically left on obviously, but labeled and functional ) on the dash or when the main batt. switch is turned off when securing the power, it was sorta just as easy and will always default back to radio sig. automagically by both means whenever/however its power comes back up(immediately by the dash sw. or a week later by the O1A2 sw.)

But mainly? If like by chance I'm not driving or something, nobody(The Admirl!) has to dig around for one of my crazy switches to get the radio working again ....I'd could get yelled at ya know?

Killing the FM is a good idea too.....hmmmm, it's a dumb ole analog radio, it will come back up right where it left off....I like it.

Edit 7/24....

In order for the widget to receive the VHF's audio and re-route this audio into the radio's speakers, a audio jack is inserted into the VHF's "Ext Speaker" plug........As expected.

By inserting the audio jack, this then mutes(open circuits) its internal 4 ohm speaker by opening the plug's circuit to the internal speaker(the VHF ext. speaker plug is known as a "closed circuit" plug when the jack is not physically present).......this creates a few issues for the intent of the design.

1) When the widget is "spliced" in place and in normal speaker "radio mode", the jack would have to be physically removed in order for the VHF's internal speaker to be functional.

2) The jack then has to be inserted each time so as to have VHF's audio signal routed to the radio's speakers when the widget is set in "VHF mode"

by the intent of the design.....Not acceptable!

One workaround would be to jumper the plug internal to the VHF so regardless of the jack being in or out, the internal speaker(4 ohm) would always play.......

This is not an issue per-se, it's on all the time now anyway, it just wouldn't mute when the jack is inserted and, would just continue to source VHF audio sig(as before) when the widget is in the radio mode. And therefor when activated into VHF mode, it would be simply parallel its internal speaker along w the paralleling the radio's speakers(4 ohms), cccccept.........in VHF mode, 3 speakers(2 - Radio, 1 - Internal) in parallel is..........

Rt = 1/(1/R1+1/R2+1/R3) = 1/(1/4+1/4+1/4) = 1.333 ohms and the audio IC in the VHF is spec'd down to 2 ohms

So the other workaround and staying w the spirit of the design's intent is to just wire an additional "closed circuit" external to the VHF using an additional relay in parallel w the VHF's closed circuit plug.......

Now with the jack remaining in(this physically and electrically keeps the VHF's internal plug as an open circuit, described above), this additional relay is able to switch open(or close) the path to the VHF's internal speaker when the radio's speakers are switched in in the VHF mode(VHF sees 2 ohms, 1/(1/4+1/4). When returning to the radio mode(VHF sees 4 ohms), it returns the VHF's to its own internal speaker and returns the radio to its main speakers,
(see updated schematic below).


The widget w all(4) relay's on(VHF mode), draws about 200mA as measured, but since it's designed to be typically only in VHF mode while running and route VHF audio into the radio/stereo speakers, obviously power consumption when activated wasn't design criteria.

However, It uses 0(zero) amps in, and defaults back to, overriding the manual button, the radio mode upon a cycling of power.

Should (When!) it fail (relays rated at 10,000,000 N.L. and 100,000 @ max rated loaded cycles) to return to standard functionality,

a) Removing the jack from the VHF allows the VHF to default back to its normal internal speaker operation.

b) Both male(speakers out, radio power in) and female(speakers in, radio switched power out) side by side molex connectors(see last photo) are pinned/wired out such that they can be removed from the widget and plugged together allowing the radio to return to its normal speaker and power connections.

 

[sam am I]

Me to, it's raining here and I'm killing time on iboats

We got fires and thick'ish smoke, trade?......

 

[alldodge]

We got fires and thick'ish smoke, trade?......

Nope, sorry, sure hope they get the fires under control soon. Hope you stay safe

 

[sam am I]

We're all good here so far, it's par for the course here in the Hundred Acre Wood . Thank you thou for the wishes, very much appreciated Dodge.