barracuda audio chip

[sinclairuser]

hi all can the audio ic on the barracuda be piggy backed to increase output?
thanks ally x

[jap]

Hi sinclairuser
There are several points:
-Will improve the sound a little bit at the expense of battery consumption and this is important.
-Will improve the sound a bit and not the depth of detection.
- of the electronic circuits audio ic some influence which is not desirable in the metal detector circuits - but if they were completely separate and isolated sufficient distance inside the box.
-Out of electronic circuits for some influence moment the highest sound pull in, which makes the device is unstable and this is important.Or customize another battery to feed audio ic.
*Observing all designs, whether amateur or professional away from this idea of these reasons - and depends on one or two TR.*
I hope I explained the points.
best time
j.

[bernte_one]

hello sinclair

some time ago i palnned here to build the cmoy audio amp
its a headphone amp search forum here or the net
if you find good layout file please post
regards

[maikl]

I do not know what the original impedance headphones for Barracuda (this is the only information that we did not get from Alexismex). I did a little experimenting with different homemade high-impedance headphones:
http://makearadio.com/misc-stuff/piezophones.php
http://www.hpfriedrichs.com/rr-pzphone.htm
http://josepino.com/howto/making-hig...nce-headphones
http://john-shortwavelistenersite-zs...-built-by.html
My ear is most enjoyed when I put handset from old phone (parallel connection 2x260Ω=130Ω impedance).

[satdaveuk]

Interesting subject
Thought it would be so stright forward to bump the audio gain up on these devices but its not.
A while ago tryed bumping up the audio on my Minipulse3 project with the 386 added extra components with preset so I could antenuate the gain of the chip manually, but problems of saturation could not be resolved for optium, ive got it working and together with the extra bass components to give it that thump on the clicks.
The outcome is, its working but there must be some sort of AGC within the chip even though followed manufactures advice to overide it.
So end results are when im hitting large surphase targets the volume is droping to lower level, on deep targets its a pleasing low bass clicking running to higher pitch as target is detected.
After reading above messages wondering maybe if its because im taking it from the same supply rail as the detector, so will try isolating and feeding from my bench supply and see if theres improvement.
Regards
Dave

[sinclairuser]

not as easy as it would appear! my first thought was to piggy back chips then i could control the interface of the two chips
basically switch position 1=normal
switch position 2=boosted audio (for us deaf old gits)
if thats not the way i bow to greater knowledge i would not be the first time the "gut" lead me up the garden path so to speak! when i started this barra project i thought my skills would make it a breeze building it was thanks to alexismex, ap berg and silverdog exellent stuff anyone who can use an iron can assemble the barracuda id tesify to that!
but thats not enough for me i need to mod improve even copy if possible and thats where the learning curve starts again for me anyway
two months ago when i started this barra i nievely posted here asking where to wire a vol pot now i understand that the threshold pot is sufficent
i have added delay pot (switched though untried yet im still in bypass) but it would be nice to have a loudness button thanks ally x

[ivconic]

Why complicating and making more troubles to yourself!!?
No need for any extra amplification.
Just mod R13 resistor and put lower value!
It is now 100ohms and can be lowered down to 4,7ohms or even lower.
Depends on your speaker resistance.
Would be good if you can obtain 16 or 32 ohms speaker.
I am using ordinary 8ohms speaker and R13 is 5,1 ohms in my Barra.
It is loud more than enough.
Or... even better (more safe for transistor) solution is to lower R13 to 2,2 ohms (or just omit and short it) and use piezo speaker instead ordinary one.
Try to find large piezo and it will burn you ears!

Cheers!

[sinclairuser]

thanks ivconic i do have a tendancy to over engineer things
what i'm aiming for is to use the speaker that came with silverdogs kit in my barra its wired to the earphone jack and only operates when no earphones are plugged in (only use speaker for testing)
i have an old pair of earphones low impedance type i use for detecting they are custom modified and only have one phone the other side is a pad for stability(im stone deaf in one ear and dont see the point in having an earphone just doing nothing!)
my barra has a mono connection to match these phones this is suited also to barra design as it has + and - audio
i will adjust that resistor now to get the best sound for my setup as it is now the sound is good just low
i know about the oversaturation now as well after reading on the net so i will try ivconics advice and keep it simple
the reason i thought of the piggyback was it was used on some radios as a quick non invasive audio mod it is basically the prototype of the add in audio cards you can get in radio mags advertisements getting two more identical chips(keeping original as a spare any problems and you just pull the chip and insert the original) seemed cheap but i must stress the ics must be identical no close matches even if sheets say ok
thanks ally x

[satdaveuk]

Thanks my old mate Ivonics, It may be well ok for me also, I dont know and cant give opinion until ive built mine, When I commented earlier was talking about my Minipulse3 and detectors in general.
Far as the Barracuda Its worth keeping in mind that the MPSA13 was supperseeded with the MPSA14 which is higher gain and has a better over all S/N ratio same pinout, so anyone who wants a bit more bumf will proberly gain by upgrading to it, or at least worth the try, so thats another option.

Nice to here from you Ivonics, hope all is well

Regards

Dave

[bernte_one]

hello

for which who go deaf the next years i recommend led output
and for those which love ghettoblaster sound i think little active speakers are best choice
sometimes i use my pringles speaker as detector soundblaster
(i wait for a version where i can adjust bass and treble)
if you have enough place on e-box you can install it there or fit them extra at detector stem

regards

[Fabian]

Barracuda sound

I do not know why, but my Bara hurts my ears!. I do not know why your detectors have sound problems or need improvement. My PCB is published by ApBerg in the forum and did not change any part, even the big capacitor (I put one of 6800UF 16V)
As in the original model, connect an LED to the output in parallel with a mono jack, and to test connected a 8 ohm speaker and the sound was very good. On the beach, use a headset that I built with a hearing protector and a headset speakers of the '70s (without any specification) and a resistor in series. I must say that my Baracuda has a very good performance ...I had to dig very deep to get beach beer cans!

Maybe some component that was replaced by another of similar value or something like that is complicating the performance of their detectors, but mine, made according to the original proyect, do not need any changes.

Regards

Fabian

[satdaveuk]

I do not know why, but my Bara hurts my ears!. I do not know why your detectors have sound problems or need improvement. My PCB is published by ApBerg in the forum and did not change any part, even the big capacitor (I put one of 6800UF 16V)
As in the original model, connect an LED to the output in parallel with a mono jack, and to test connected a 8 ohm speaker and the sound was very good. On the beach, use a headset that I built with a hearing protector and a headset speakers of the '70s (without any specification) and a resistor in series. I must say that my Baracuda has a very good performance ...I had to dig very deep to get beach beer cans!

Maybe some component that was replaced by another of similar value or something like that is complicating the performance of their detectors, but mine, made according to the original proyect, do not need any changes.

Regards

Fabian

Thats good news for me because im also building from the origonal lay files almost finshed just waiting for a couple of parts because wrongly thought that I had them in stock.
Regards

[sinclairuser]

Thats good news for me because im also building from the origonal lay files almost finshed just waiting for a couple of parts because wrongly thought that I had them in stock.
Regards

ah that old chestnut!(though when i have had this problem it was allways due to pilferers mixing my drawers up which led me to think i had stuff in stock but on inspection were some other random crap!)

thanks for the tip about the chip i'l see if i can find one and try it this is for my own barra by the way i'm still going to build another one with all original components and am monitoring certain threads
so i'm very interested in your progress satdaveuk as i said before this forum can discover the secret of the barras missing components if motivated correctly and if not then we will do it ourselves
thanks ally x

[Sean_Goddard]

ROFLMAO!!

Come on guys...Look at this as a simple audio amplifier, put a 10uF cap across the 100R emitter resistor (it's called a bypass capacitor)..Should give the result you're looking for (unless I'm teaching you to suck eggs in which case, just tell me to get lost) .

Also, if the audio supply is connected to the cathode of D8 then WHAT is D8 doing? Nothing that I can see, unless it's the wrong way around??

[sinclairuser]

ROFLMAO!!

Come on guys...Look at this as a simple audio amplifier, put a 10uF cap across the 100R emitter resistor (it's called a bypass capacitor)..Should give the result you're looking for (unless I'm teaching you to suck eggs in which case, just tell me to get lost) .

Also, if the audio supply is connected to the cathode of D8 then WHAT is D8 doing? Nothing that I can see, unless it's the wrong way around??

not at all mate that is the simple kind of idea that gets too easily forgoten when your too close to a problem as for teaching me to suck eggs thats cool we forget most of what we learn so i have no problem taking on fresh knowledge from people who know better! the diode does look wrong though
thanks ally x