I can Hear it !...Super Amp...

[geoscash1]

As you have probably already figured out I am always having a hard time hearing so have been looking
for a simple way to amplify the sound on my detectors (surf pi and barracuda).

I like to have a good volume from the speaker mostly because of rattlesnakes where I hunt, dont like having my ears covered just in case but sometimes there is enough of a breeze also that the faint sound from the audio just isnt enough for me to hear since I'm half deaf...lol

I have made a few amps from circuits I have found online and have also bought a few off ebay from china, Finally found one that works like a real amplifier and definitively increases the speaker volume 10 fold, it will even over amp them. It has an on board resistance trimmer, which I set at 50% or half way which is good for me. The board is small, 1/2"W x1-5/8 L" and will work from 4.5 to 12 v so a 9v batt works perfect.

I built them using a small radio shack box, one for 32 ohm speaker and one for an 8 ohm speaker, that way I have one that will work with different types of metal detectors, like the barracuda with the 32 ohm and my surf pi which has an 8 ohm. Its small enough to fit in a shirt pocket and light enough you wont even know it.

Anyhow, below are some pics of the 32 ohm unit, which will attach quickly using velcro to the top of whatever detector I'm using at the time.. I thought I'd share because I'm sure there are others that would like a bit more volume when using just a speaker instead of phones. Also added the link for the amps from ebay.



Link to the amplifiers - http://www.ebay.com/itm/LM386-Audio-...item20cdfddaa0



p.s. having issues attaching images, not sure what why but had to use the "basic uploader" to get images attached.

[golfnut]

they will drive a Tx coil too -

[6666]

You are going to a lot of trouble , no need to modify your MD, get your self a set of
ELECTRONIC ACTIVE PROTECTIVE EARMUFFS , used on gun ranges and work sites with very loud noises,
they cut off above a certain noise limit,
these ear muffs have a built in amp and are very good, they will amplify these RATTLES you are worried about.
There are tons on fleabay

http://www.ebay.com.au/sch/i.html?_t...at=0&_from=R40

[geoscash1]

Hey 6666,

Actually that kind of defeats the purpose for me, I like building things and really enjoy it when something comes together and works well
that I built myself.. Already have a 200 dollar pair of shooter muffs but that's what I use them for and nothing else..

I pride myself in doing things or making something that not only saves me a few bucks but has a benefit to what its for...

All is good... I truly do have more fun spending time in my garage and making something useful versus just buying it..

Thanks for the suggestion though, it may be well worth it for someone else who doesn't want to waste the time building something..

[morganton]

Interesting thread because I'm also hard of hearing.

If you really want to be able to hear the snakies, maybe you could get rid of the sound entirely and use a vibrating system like your phone has when it is on silent mode. There has been some discussion of this-- http://www.geotech1.com/forums/showthread.php?15522 Also, here is a possible circuit from the same thread allowing you to switch between the vibrator and a speaker. http://www.geotech1.com/forums/attac...&d=1244737138I

If I get some time, I might design an add-on for the barracuda. Maybe a vibrator by the handle grip or a wrist attachment.

I have a lot of hearing loss above 1KHz and have thought I might eventually have to do something like that.

I know for the Hammerhead, that there has been some discussion of how to modify the circuit to lower the frequency to around 300Hz for the hard of hearing.

Also regarding the barracuda, the led that can be installed works pretty well as a mirror of the outputted sound.

[Davor]

If you are able to salvage a small transformer from any of those "6 transistor" receivers, you'd be able to boost volume without any extra power consumption. Point is that a small speaker on very loud has a voltage across it of a volt or two, and the most of the audio drivers in our detectors are current ones, so placing a 4:1 transformer makes your speaker loud. It works for me.
Otherwise, you could simply replace every 8ohm speaker with 32 ohm or more. This trick works with current drive.