Barracuda Volume

[geoscash1]

hey guys,

I haven't really payed much attention to sound with my barracuda until this morning. I have been using a 32 ohm speaker (bought a half dozen on ebay from china) for testing so haven't given much thought of headphones.


This morning I was testing and messing around with a newly wound coil when the neighbor fired up a wood chipper so I decided to put on my headphones..



Well, now that I am deaf from waving a silver dollar over the new coil I need to ask, can I put a volume pot in series with the wires from the board to the headphone jack, I assume so but wanted to ask to make sure so as to not screw something up.



Has anyone else blasted their eardrums with a new board? I used all stock parts except for the TLO82 and the 6800 cap, the rest is what came with the package.. It is way to loud to even try and wear headphones even with the threshold turned to silent op, when an item is passed over the coil it is hella loud.... When I plug my external 32 ohm speaker in it is fine, volume is nice, fact its about perfect.


Is there a specific resistor that may be of wrong value or maybe the TLO82 I used ??? .. I cant figure out why it is so loud with the headphones but not with the open speaker.

Anyone have some advice?


Thanks in advance for any help

[bernte_one]

put a simple potentiometer of 1k in line of audio plug (logarithmic pot is better for audio volume control)

[geoscash1]

Thanks bernte_one

I assumed that would be fine..

Have you had any cuda's that were screaming loud?

[bluebenz1]

I have the same problem...will be putting a volume control in...!!!!

[kt315]

[Koala]

I have the same problem with my IDX

Thought about adding a volume but this would reduce the faint signals as well

What is need is a audio limiter that does not affect the lower volume sounds but all above a certain volume is cut off without affecting the quality of the tone.


Did find some commercial one to stop kids from damaging the ears playing music too loud but they were expensive. Others just chop the volume with a diode so the tone is affected. Have to have another look as some fields full of plow shear makes my ears buzz

[kt315]

use IC's amplifier. too low price mc34119.

[greylourie]

This is interesting. A search for other opamp with disable pin gave LTC6091. But I wonder if it could be done with simpler components ?

[Koala]

http://mickael.devisschere.free.fr/p...imiter_prj.htm

Seems some kids headphones already have the limiter built in. Probably not worth making if we can find a pair of headphones that are of sufficient quality

https://www.google.co.uk/#q=kids+headphones+with+audio+limit

[bluebenz1]

Interesting...all BBC headphones have to have a limiter....might start with the kid's version....
http://www.canford.co.uk/Index/Headp...S-AND-HEADSETS

[greylourie]

http://mickael.devisschere.free.fr/p...imiter_prj.htm

Seems some kids headphones already have the limiter built in. Probably not worth making if we can find a pair of headphones that are of sufficient quality

https://www.google.co.uk/#q=kids+headphones+with+audio+limit

The article in your first link covers some (hard and soft) clipping arrangements. Funny enough, but the Goldscan has both. But this is a Barracuda thread, and I have Goldscan on the brain.

[Koala]

Interesting...all BBC headphones have to have a limiter....might start with the kid's version....
http://www.canford.co.uk/Index/Headp...S-AND-HEADSETS

Seen the Canford ones but did not fancy taking out the bank loan to pay for them.

[Koala]

Finding specification of audio limiting headphones is hard. Suspect most are just a resistor add so will affect the softer sounds also.

dB Logic SPL2 looks interesting. Does not affect the lower sounds and no batteries required and very cheap. Not sure it will work for detectors as on one site did say it took awhile for the limiter to kick in. Still searching for its proper specifications. There was also an inline module for $20 but can't find any listings in the last year.

[bluebenz1]

went out for the first time with a detecting group on farm land and my home brew barracuda ...some interesting observations.... it was no match for the xp deux's...however...it did find various bits of rusty farm metal including a horse shoe...so if its big and rusty...I'm your man....mind you no one else found anything more than a couple of old pennies......I used head phones and the buzzes almost blew my ear drums out..I couldn't wear them over my ears, bloody awkward trying to get headphones to sit anywhere other than on ones ears...i found that if i moved the coil end of the detector with a bit of a twitch it would buzz as if detecting something also a feint buzz at the end of each gentle sweep....summery pleased that it found anything at all...but seemed very unrefined.
Powered with 8 AA batteries, coil-200mm 0.4mm enamelled wire, can't remember how many turns unshielded.

[Koala]

went out for the first time with a detecting group on farm land and my home brew barracuda ...some interesting observations.... it was no match for the xp deux's...however...it did find various bits of rusty farm metal including a horse shoe...so if its big and rusty...I'm your man....mind you no one else found anything more than a couple of old pennies......I used head phones and the buzzes almost blew my ear drums out..I couldn't wear them over my ears, bloody awkward trying to get headphones to sit anywhere other than on ones ears...i found that if i moved the coil end of the detector with a bit of a twitch it would buzz as if detecting something also a feint buzz at the end of each gentle sweep....summery pleased that it found anything at all...but seemed very unrefined.
Powered with 8 AA batteries, coil-200mm 0.4mm enamelled wire, can't remember how many turns unshielded.

Think you will be surprised on a cut quarter in mineralized ground between you detector and a Deus. After its been fine tuned.

Had a look through TK Maxx headphones and earbuds today. Only one set said it limited to 85dB but there was no mention of how it was done so suspect its just an inline resistor.

Several around the £10 with a volume control but you will loose the faint signals.

I sometimes run my IDX with 0 discrimination. I pinpoint a target then work out how big it is. If its a large or long an thin target I walk on by. Tend not to dig too much junk plogh shear or horseshoes. Seen some nice iron artifacts but not by me yet like a medieval cast iron thimble and some lovely rose mounts.