questions in general?:ausflag:

[blowfly1967]

1. what is vco and what does it do ? if you have time monte?
2.when i say i can hear different targets in the 450hz range and know pretty well what they are before i dig.
but when i use a detector that operates in the
630hz range however,i will still dig every responce,even though every target sounds like ,phut,phut.dull and uninteresting
.no clues what i'm digging up.the question is,which way does the hz run.low hz base or trebble.or high is what?
3.out there in detector land is there a set of earphones that has not only volume control,
but also audio adjust for those hearing inpaired detectorists that can't hear every nuance that all the young bucks can?
h h hooroo blowfly

 

[BarberBill]

I can help on the VCO question. It means either voltage controlled oscillator or volume controlled oscillator (I've forgotten which) Anyway, it is what makes the all metal pinpoint or all metal mode raise in pitch as the target gets closer to the center of the coil or, conversely, lower in pitch as the coil moves away from the target. On machines without this feature that have all metal pinpoint or all metal mode the beep is a single pitch/volume beep like generally heard in the discrimination mode.
HH
BB

 

[tab-nabit]

I can help on the VCO question. It means either voltage controlled oscillator or volume controlled oscillator (I've forgotten which) Anyway, it is what makes the all metal pinpoint or all metal mode raise in pitch as the target gets closer to the center of the coil or, conversely, lower in pitch as the coil moves away from the target. On machines without this feature that have all metal pinpoint or all metal mode the beep is a single pitch/volume beep like generally heard in the discrimination mode.
HH
BB

Voltage Controlled Oscillator

 

[Monte]

First, the question. I'm curious about how some 'name' come about, in your case "blowfly" as well as '1967'?

1. what is vco and what does it do ?

VCO stands for Voltage Controlled Oscillator.

In our much earlier days of metal detecting you had basically two principles of operation to choose from: BFO or T/R.

BFO stands for Beat Frequency Oscillation and T/R stands for Transmit/Receive, and was also known as I/B, for Induction/Balance. The primary perceived difference between these two principles is that a BFO is a fixed-volume, frequency-change design. The detector was tuned for a motor-boating audio where you would hear a low frequency beating or putting. When the generated field was brought closer to a metal target the volume was the same, but the frequency changed resulting in progressively faster beats as the pitch (frequency) increased to its peak when the metal target was in-line with the coil's center axis. While it sounded like it got louder, it wasn't really a loudness or volume change, but a pitch or frequency change.

The I/B or T/R principle of operation relied on a model designed to operate at a fixed frequency, such as 6.592 kHz, and you would adjust the tuner control for a slight audio threshold of sound. As the search coils EMF is brought into the presence of a metal target, the frequency doesn't change, but the volume does because this principle of operation is a volume or loudness change design.

In short description, what VCO audio does, is provide a pitch (audio frequency) change with the increasing audio volume we hear on a target response.

The benefits of having a VCO audio are two. One is that some people's hearing can interpret the response much better, and the second and primary benefit is that it can aid in pinpointing a target because we can hear both a volume (loudness) increase as the coil is centered over a target, as well as the VCO pitch increase.

I like a good VCO audio design, and that means (to me) one that can be controlled or is factory designed so that it doesn't peak too quickly (making it almost useless), and a VCO mode that doesn't have a fast auto-tune circuitry, which sort of defeats the purpose/benefits of a VCO audio for pinpointing.

2. when i say i can hear different targets in the 450hz range and know pretty well what they are before i dig.
but when i use a detector that operates in the 630hz range however, i will still dig every responce, even though every target sounds like ,phut,phut.dull and uninteresting . no clues what i'm digging up.

the question is,which way does the hz run.low hz base or trebble.or high is what?

The lower, bassy frequency (lower Hz) are easier for some ti hear, while others enjoy the more treble-sounding higher audio frequencies (higher Hz) better. Then there are those of us with hearing loss in various frequency ranges and a ringing in our ears that makes detector selection "interesting." Some makes and models just don't have enough audio 'bark' for me, and some just have an audio frequency that I have difficulty hearing or perceiving subtle target responses.

3. out there in detector land is there a set of earphones that has not only volume control, but also audio adjust for those hearing inpaired detectorists that can't hear every nuance that all the young bucks can?

I don't have great hearing. I wasn't able to be hired as a permanent civilian employee at Hill AFB because I failed the hearing tests. That was in '82, '83, '84, '85 and '86. I worked temporary for the summers, but all testing I had as part of the hiring process resulted i them telling me I was deaf. they asked if I wore hearing aids, etc. No, I don't, but I sure have a tough time hearing certain ranges of sounds like I use to, as well as weak or faint sounds.

The absolute best headphones for me and my hearing problems have been the Killer B 'Wasp' and SunRay Pro Gold. That's all I use and I have tried most anything than comes along. we all hear a bit differently and you might have to try several to determine a brand that you prefer, but the Killer B Wasp & SunRay Pro Gold headphones (basically the same headphone) fit well, don't flop around, and the audio is excellent.

Monte

 

[grumpyolman]

There's some good audio folks on Eriks Audio World in another part of Findmall. Might get some more info there or post there as well. Definitely some discussion going on about what to do with a friend who has major hearing loss and wants to detect. What machine might he get.

 

[blowfly1967]

thank you monte.your wealth of knowledge astounds me sometimes.i think i told you i read back through all your old posts on anything that touched on tesoro.man that was a lot of reading.retained some knowledge,forgot a lot,but i know where to look in future.when i joined this forum i had to decide on a name to identify with as we all did .my wife came up with the name.her cat's name is blowfly.in australia anyone who keeps sticking his nose into things is sometimes called a blowfly .i'm 67 years young and my wifes birthday is 1967.we have been married for 23 years,have three grown up children.i think that classifies me as a dirty old man.ah well such is life! see ya blowfly.

p.s.the wife says could you not interface a small graffic equelliser between the earphones and the detector,battery operated.would that not give a better quality of sound,for the hearing impaired. blowfly.