Way Off Topic: Need a signal generator.

G

ggrantly

Veteran
I am sure the audio braintrust can help me with this.

So I have a 17' skiff I am restoring and and want an automatic fog horn. Typically this is done with a VHF marine radio and a 4 ohm hailer horn. The foghorn amplifier and timer functions are built into the radio. Except, the nice and new VHF radio I have lacks this feature and don't really want to replace the radio for $400. So want to buy or build a magic box to do this. Must run on 12Vdc or less (could use a resister to lower) I need a minimum of 100-120db. Frequency TBD, as long as it is plenty loud. I could control the off and on with a momentary switch, but a timer would be better yet. Typical you do a 5 second burst every minute.

Seems like this would be really cheap to build from an electronics supplier, but if there were a kit that could get me close, that would be great to save some time. I did some google searching, but came up empty.

Like I said, off topic. But not to far off, we use tone generators all the time right?

TIA Grant
 
you don't want a signal generator (they look like this https://uk.farnell.com/multicomp-pro/mp750064/arbitrary-function-generator-1/dp/3130264 ) what you need is an audio tone generator.

Try searchin on "fog horn tone generator kit" and they run from about £/$10 upwards. see http://brocott.co.uk/fog-horn-sound-generator-kit/ (I am sure there are lots of US places local to youy that do similar. Though I note on the link that they also do a Destroyer Siren kit.... you might want one of those too, just for fun.
 
ggrantly said:
I am sure the audio braintrust can help me with this.

So I have a 17' skiff I am restoring and and want an automatic fog horn. Typically this is done with a VHF marine radio and a 4 ohm hailer horn. The foghorn amplifier and timer functions are built into the radio. Except, the nice and new VHF radio I have lacks this feature and don't really want to replace the radio for $400. So want to buy or build a magic box to do this. Must run on 12Vdc or less (could use a resister to lower) I need a minimum of 100-120db. Frequency TBD, as long as it is plenty loud. I could control the off and on with a momentary switch, but a timer would be better yet. Typical you do a 5 second burst every minute.

Seems like this would be really cheap to build from an electronics supplier, but if there were a kit that could get me close, that would be great to save some time. I did some google searching, but came up empty.

Like I said, off topic. But not to far off, we use tone generators all the time right?

TIA Grant
Click to expand...
I like the Fog horn kit but another option is an MP3 player board. I build some sound playback devices for an installation with them. They run about $6 on Amazon (or like a buck fifty in bulk from China). Stick whatever you want on a USB stick or micro SD card and it will play when you give it power. Since they can loop the "playlist" just put your horn with a minute of silence added as the only file and it should go as long as you give it power. It has an amp built in but you may want to pick up a higher output amp board at the same time. I saw 50 Watt boards for about $10.
If you go this route and use the micro sd card you may have to add some load on the USB input. The micro cards draw so little power that they were causing some of my devices to decide they were done and turn off. The horn sound will draw enough but the gap may trick it into shutting down. USB pen drives drew enough power that there wasn't a problem.
 
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