increased voltage

[Anonymous]

l have a whites surf master pi. ls their anything ,to be gained by, increasing the voltage ,by 1.5 volts, as they do with minelab pi. Luke <img src="/metal/html/wink.gif" border=0 width=15 height=15 alt="">

 

[Anonymous]

http://www.siliconchip.com.au/cms/A_100886/article.html
what you think about.

 

[Anonymous]

Mr Bill,you must have fair idea, as to their being an advantage, in running the whites surf pi on 13.5 volt nihms or 12 volts nihms. Will this damage detector, in your opinion. Regards Luke.

 

[Anonymous]

You can run it at 13.5 volts.
Your getting close to the outer edge, with no room for mistakes for the circuit.
I don't see any advantage, outside of trying to regain voltage loss going to the NiMH cells, (1.5v to 1.2v of the NiMH cells).
If this is a standard Surfmaster PI, and not the PI Pro, the biggest advantage you could do for it is to have it modified to a 15uS. pulse delay. The gains would be very noticable.
Please excuse, I was not trying to make this answer a plug for my modifications. I'm sure they are others that could do it for you. <img src="/metal/html/smile.gif" border=0 width=15 height=15 alt="">
Mr. Bill

 

[Anonymous]

Hi Luke,
I do not own a White's Surfmaster, but I have increased the voltage on a few other units, including the Beachscan, my GQ clone, a Hammerhead by Carl Moreland, and a couple of kits.
Now, I have never seen any significant or even a minor depth increase by increasing the voltage by 1.5V. What does happen on most units is the audio gets a little louder, which makes it appear that the detector is more sensitive. However, just adding a separate mini audio circuit ampilifier can do the same thing. In fact, the Radio Shack mini amp ML owners discuss on a couple of other forums adds more gain and sort of isolates the audio loading. This addition makes it easier to hear minor changes better and can be used on many of the PI's out there.
Reg

 

[Anonymous]

Mr Bill l live in Australia other wise l would gladly get mod done.The nihms batterys are suppose to run, close to their maximum voltage and only drop off in voltage, right near the end .Nicads have a much greater decrease in voltage performance.The Minelab pi run better on voltage increase.Reg thank you for your reply,interesting.Does any body know why they make most rechargables in 1.2 volts.That is my understanding of nihms,dont know if it is right.Thanks for replys. Luke.

 

[Anonymous]

Hi Luke,
There has been several interesting discussions about the ML and the increased voltage, none of which really explained what was going on. I am relatively sure any increase in depth that may have been see was not the result of the additonal power into the coil. The basic laws of physics apply to ML's also.
The logical answer why the small increase in voltage seems to help would be the increased voltage made the detector more stable which could help one distinguish object signals from noise.
Now, I am not sure why rechargeables are 1.2V. What I do is use a 10 pack, instead of an 8 pack. This adds a little weight but gets the voltage back up to 12V. Actually, I don't add the two batteries for the increased transmit power one might get from the additional voltage, but rather because I have added additional circuitry and the + V supply is marginal because of the additional loading. The extra voltage gives me a little extra room for more experimenting.
Reg

 

[Anonymous]

The voltage of a battery is set by the inherent properties of the materials from which anode and cathode are made. The electrolyte between anode and cathode has a minor effect on cell voltage.
The energy storage capacity, rechargability, et al, are set by the chemistry of anode, cathode, and electrolyte, so one chooses a battery type for these properties, and lives with the resulting voltage.

 

[Anonymous]

Hi Luke,
I don't know about the Minelabs or the Whites PI's, but I have noticed something strange with my Goldquest. When I tried different battery combinations, I found that when using a 10 Volt NiCad pack as opposed to a 12 Volt Alkaline, the NiCads give a much more steady and stable unit.
I've not tried a 12 Volt NiCad pack yet. I'm not sure what's happening, but I suspect that the higher voltage is increasing the white (thermal) noise inherrently generated in the circuitry, and this is causing the instability, and interferring with legitimate signal processing. In other words the higher voltage reduces the useful signal to noise ratio. Alternatively one of my amps has a defect? I must look into this sometime.
Also the extra voltage doesn't seem to give much of an increase in detection depth, if any. It's likely that what Reg says is correct, the audio block becomes more sensitive, and gives the illusion of greater sensitivity.
I'd go with Bill, and Reg's suggestions for guaranteed improvements.
Cheers
Kev.

 

[Anonymous]

Hi Kev,
NiMh's do seem to be more stable voltage wise, but even they will bounce around a little if the audio is activated heavily from a very strong signal. Now, once a battery gets weak, whether it is an Alkaline, a NiMh, or a NiCad, the voltage droop at the FET becomes quite noticeable. This can lead to instability problems.
I normally run my PI with 10 freshly charged NiMh's and it runs super stable.
Now, for another little trick. This works well for those who hunt in areas where there is additional background noise.
To minimize the problems caused by the background noise, you might want to try a set of noise canceling headphones. I was amazed just how much of a difference it can make.
One can use passive types such as Koss units (don't remember the number) , or active types, such as my Aiwa HP CN 6. The Aiwa are really quite sensitive also. I picked up both the Koss and the Aiwa units off Ebay quite reasonably.
Now, I combined the little preamp plus the noise canceling headphones and I could add almost a couple of inches in depth in an air test of a US nickel.
It does make a difference.
Reg

 

[Anonymous]

I have heard that the pulse delay of some units maybe be decreased by supplying more volts into the circuit. i.e. 15us to 14 or 13us perhaps?
I have increased the voltage on my SURF PI PLUS and PI PRO to 12.4v using a home made 3 cell lithium ion battery pack. I was happy with the results from both detectors.
As for my old GQ SS, I did not have noticeable improvement using higher voltages. Actually, more instability was experienced. It is possible that the pulse timing was also being affected, possibly lower than 10us, making it unstable. To my knowledge, the new GQ SS v.2 has been improved with a new circuit that sets the minimum delay to exactly 10us.That is a great improvement, in my opinion, to an already very good PI machine.
RE: Minelabs PI's, looking at the battery used for those machines, I assume that they are higher powered machines (high amp draw) which would probably punch deeper into the ground with more voltage. Im just guessing though.
rgds, bing

 

[Anonymous]

I measured the change in pulse delay on the Goldquest SS when going from 12V to 14V and it only amounts to less than 0.5uS. Not enough to give a noticeable change in sensitivity. This would also amount to a 16% increase in transmitter current, but when you consider that 100% increase in TX current will only give about 10% more range, then going from 12V to 14V will not be very noticeable either. There will also be a small shift in TX frequency, which could result in changes in the threshold noise, if you are getting interference from a local transmitter. Also, as has been pointed out, the audio will be a bit louder, resulting in threshold noise being more perceptible.
Best to stick with the design battery volts of 12, as higher voltages will give little benefit and could put the electronics, and the warranty, at risk.
Eric.