spaceman41 said:
Hi let me introduce myself,im Johnny from over in tthe United Kingdom, ...
Johnny, 'Welcome' to the Findmall White's Forum. You can usually find me on one of the better brand White's Forums [size=small](the ones I like
)[/size] or on the ahrps.org forums, and if I can ever be of more specific help, you're welcome to shoot me an e-mail to monte@ahrps.org or to monte@stinkwaterwells.com and we can converse that way. I do fall behind from time to time due to the volume of mail, and I have to fit the Internet stuff in where I can when not out detecting.
There are quite a few helpful and knowledgeable folks on here, so always ask away!
spaceman41 said:
i have a question or two about GEB ...
Okay, and let me ask a question or two to get started. Are you new to the metal detecting hobby, or have you put in some time with other makes or models? Do you know what GEB means?
If the last question is answered 'No' or 'Not sure,' then let me explain because I am asked this type of question a lot. GEB is White's terminology for Ground Exclusion Balance. In short, it means the detectors operating mode is able to adjust to cancel some of the ground mineralization. Prior to 'Ground Balance' we had traditional or conventional T/R [size=small](Transmit/Receive)[/size] operation that didn't have that capability. Using the 'traditional' T/R [size=small](non-Discriminating)[/size] or T/R-Discriminate models meant you [size=small](the operator)[/size] had to deal with the ground mineral effect of the electromagnetic field [size=small](EMF)[/size], and that required the operator to maintain a fairly consistent coil-to-ground relationship.
Once we had detector circuitry to balance-to, or cancel-out, or 'ignor' the mineralized ground, then that search mode provided us ease-of-operation in our searches as we could vary the search coil position a little without any false responses. When you used the early VLF Transmit/Receive detectors, without any target rejection and with the ground mineral effects cancelled, you were in essence searching in a mode that would respond to ALL metal targets that differed from the ground mineral, and that included all ferrous as well as non-ferrous targets.
Also, in order for the manufacturers to take the original T/R circuitry designs [size=small](which operated at-or-about 100 kHz)[/size] and make them able to cancel the ground mineral effects, they had to reengineer them to operate somewhere between 1 and 30 kHz. That is called the Very Low Frequency, or VLF, range. While some models worked at lower frequencies, and a few work at higher frequencies, the bulk of the more popular detectors that operate in the VLF range fit between about ±5 kHz and ±15 kHz.
Forty years ago it was 'popular' to refer to all makes and models that operated in a ground cancelled mode to be called VLF. We associated VLF as being an All Metal mode, and soon they incorporated a 'traditional' T/R-Disc. circuitry in them so we had two operating modes. VLF, for all metal target detection while ignoring the ground mineral effects, and T/R-Disc, which let us check some of the targets we located by using some amount of Discrimination to reject unwanted stuff, like iron, foil, pull tabs, etc. But the T/R-Disc. operation didn't cancel the ground signal.
Naturally, as is the trend in this detector business, each manufacturer had to come up with their own terminology to describe a mode that let the operator ignore the mineralization effect. Aside from the early-day use of VLF, White's went with GEB, while other manufacturers over the past forty years have used terms to describe this mode, such as:
GA [size=small](Ground Adjust)[/size]
GB [size=small](Ground Balance)[/size]
GC [size=small](Ground Cancel)[/size]
GNC [size=small](Ground Neutralizing Circuitry)[/size]
GEN [size=small](Nokta's term for General Search or All Metal mode)[/size]
Normal [size=small](For a 'Normal' find-it-all mode w/o Discrimination)[/size]
All Metal [size=small](perhaps the best term for a ground cancelling mode w/o Discrimination that responds to all metals, both iron and non-iron)[/size]
There have been other terms but this might help unconfuse some readers newer to the hobby, but acquiring older, discontinued detectors.
Back to 'GEB.' Ground Balance let us hunt while ignoring the ground, but early on we had to switch to a conventional T/R-Disc. mode to check the targets, and that mode wasn't ignoring the ground mineral signal. Then about 1978 George Payne brought us the Bounty Hunter Red Baron with what he called SPD. Oh great, another term to learn!
Well, SPD stands for Synchronous Phase Discrimination, and it differed from regular T/R-Disc. because this mode let us search in a Ground Balance mode AND Discriminate unwanted trash at the same time. The early VLF-Disc. mode was then available.
This let us ignore the ground signal as well as ignore unwanted trash signals. To accomplish that task, however, the search coil needed sufficient sweep speed to get a ground signal, a target signal, then the ground signal and the circuitry would then ignore the ground signal and pass along the target signal. On those earliest VLF-Disc. models, or SPD modes using the Bounty Hunter Red Baron label, the search coil had to be swept at almost a golf club swing. Very fast. As the next few years progressed we saw improvements to slow the sweep to a moderate speed on the early 4-filter models, and then since '82/'83 we have had the trend to slow-motion, quick-response 2 and 3 filter type detector designs.
Because it required search coil motion in the VLF-Disc. aka GEB-Disc. mode, this new Discrimination mode was called a Motion-Disc. operation. Motion-Disc. is a Ground Cancelling and Discriminating search mode. Now, on to sort through your comments and questions.
spaceman41 said:
The audio 'Threshold' level is a proper setting where you adjust to just barely hear a Threshold hum. Not too loud and not too soft or quiet, in the conventional GEB All Metal search mode, just a comfortable 'Threshold' setting. You have a White's Coinmaster Classic III. I presume that is the earlier version in the more squarish control housing and is powered by three 9-Volt batteries?
If so, you do not have any outside Threshold adjustment on the control panel with those models. That was internally set my the manufacturer. You have a 'silent search' Discriminating detector, but you will hear a Threshold audio hum in the GEB All Metal search mode.
spaceman41 said:
i seem to have read. somewhere that with my Whites Classic coinmaster III thats its posssible to hunt with the toggle set to GEB constantly?
If I am correct on the Coinmaster Classic III model you have, on the control panel in front of the hand-grip there is a center positioned toggle that is labeled GEB/DISC. under it. To the left it says Reset/PP[size=small]( Pinpoint)[/size] and that is a momentary position. When released it is spring-loaded to return to the center position.
The center toggle position is labeled GEB/Disc. [size=small](meaning GEB to ignore the ground signal and Discrimination of unwanted targets)[/size], and this is a silent-search, quick-response search mode. The Coinmaster Classic III is a 2-filter type that is a slow-motion detector. Do not use a fast sweep, especially in very mineralized ground.
The right side toggle setting is labeled GEB and this is the basic All Metal search mode. Here you have a Threshold audio hum, and it is not a motion-based search mode and you'll find both iron and non-iron targets.
So, 'YES,' you can toggle to the GEB position and search in the All Metal mode.
spaceman41 said:
You can use the GEB selected setting to Pinpoint a target you have located, but it is best to use the left-side setting that is 'PP' as this is a momentary setting as long as you hold the toggle there and isolate the target position. Then you release the toggle and it goes back to the silent-search motion-based Discriminate mode.
spaceman41 said:
Ive seen that people have said you set the threshold to just about comfortable can someone please explain this to me?
If you have a make/model detector with an external Threshold control, you can select the All Metal search mode and adjust the tuner for a nice-and-proper slight audio 'hum,' better referred to as the audible Threshold level. Your model doesn't have that adjustment.
spaceman41 said:
On my understanding which is very little really that GEB is no discrimination and that I will detect deeper i.e that the higher the Disc setting the less depth detected at.
The right hand GEB mode, your All Metal search mode, can usually detect a little deeper than the silent-search motion Discriminate model, which is your center toggle GEB/Disc. operation. The Discrimination level only effects the performance in the GEB/Disc. mode, not the All Metal GEB mode.
spaceman41 said:
Is it okay for the machine to search in this GEB mode to the right or will it wear the batteries down quicker?
You can search in that mode, but it is best to usually use the center toggle mode of GEB/Disc. Why? Because not only does your model not have an external Threshold control, unless modified it also doesn't have an external Ground Balance control. Thus, you are relying on the internal preset GB, and that's usually just a bit positive. Thus, hunting in the GEB mode you might have some audio fluctuations you'll hear as the ground contour changes and the search coil is lifted away from or moved a little closer to the ground. Also, hearing the slight audio hum can cause some slight drain on the batteries.
Oh, one reminder about batteries, if you have that early Classic III model with 3- 9V batteries. Two of them power the operating circuit and one powers the audio response you hear. The batteries should be rotated periodically to provide more consistent wear-down.
spaceman41 said:
I have just got into using headphones!!! my m8 doesnt like them with his Ace Garrat 250 but Im getting sounds i never had before ones that didnt come through on the main speaker.How is this?
With headphones you'll likely hear the GEB mode's Threshold better than though the speaker, but that's by design. I use headphones all the time, unless demonstrating a detector to someone or doing a seminar for a group. Use some quality headphones and it will provide more attention to target responses, block out disturbing outside sounds, and they can add a little more battery life than using only the speaker.
spaceman41 said:
Ive heard Monte is the expert on this thanks to Douglass Millar (Facebook).
Expert? I'm not sure about that, but the guy does have a bit of experience from fifty years of very active metal detecting.
I hope I have helped you or some reader. Now it's out-the-door for a couple of hours of detecting before dark.
Monte
