Silverdog Surf PI Modifications

[chemelec]

If you use HIGH Impedance Headphone, (600 Ohm) you will get Better Volume.

[multieagle]

I've found the warble at a certain point when adjusting the delay. If you turn all the way clockwise, using a small gold ring, turn trimmer back until the gold is no longer detected, then back the other way just until the ring is detected. This will have it most sensitive. Otherwise, for general hunting just adjust the trimmer until you get the maximum distance, say on a silver dime, quarter, or whatever is your silver currency.

[Sean_Goddard]

I had the prtoblem on my orig build years ago. On geotech was the solution that worked for me.
Change out a resistor to a different value to suit your needs.

[ATTACH]29259[/ATTACH]

Put a 10uF cap across the 33R for AC bypass you will get a MUCH LOUDER volume then.

[muddy fingers]

I have a Whites PI surf Pro and the threshold noise you hear is a warble rather than the constant hum you get on VLF machines.

[godigit1]

Hi Multieagle,

Maybe this is not a issue anymore as it has been awhile since you posted on this thread.

If Not. Have you tried a different coil? It almost sounds like the coil is overloading and the machine goes pretty much silent and becomes un responsive. Since you have increased the gain you may now be picking up your copper shielding Or even solder joints at the coil and overloadind. I cannot solder my shield connection as just that overloads my smpro kit. I have some coils I cannot use anywhere indoors. As a matter of fact all my indoor testing is on a 4 or 6 inch coil as that is all that will work in my place without overloading.

[Sean_Goddard]

I have a Whites PI surf Pro and the threshold noise you hear is a warble rather than the constant hum you get on VLF machines.

I suspect this is some sort of "beat frequency" caused by the 7660 -ve generator.

If you have a split bench PSU try removing the chip and running the machine from that.

The Surf PI doesn't have decoupling caps across the 4066/16 and timing delay IC as a result it is terrible for random signals. Also, it you are using the 9640 FET then the switching goes all to pot as the battery voltage drops, the Tx pulse looks like cr@p after about 9V. What is needed is a regulator on the FET drive circuit to hold a constant drive level, but then as the FET is running directly from the battery, the quiescent conditions change on this quite badly too.

[multieagle]

Thanks for the feedback. I am still experimenting with this board . . . sometimes it works, most times it does not. But hey, it is fun!

Question: I notice some using smiley icons not included on the forum list. How do you insert your own smileys into a message?

[multieagle]

I am still having problems with the delay pot. Question: In changing the delay trimmer to an external linear pot, should it be 100k, or would 10K work? Also, which resistor R9 or R25 is related to the Delay trimmer?

[SVEN1]

Hi Gordy,
You need to use the same value external pot as the value of the trimmer. Linear.
look at it this way
100k pot adjustment from 0-100k.
10K pot adjustment from 0-10k.
If you sub a 10k for the 100k, you lost adjustemnt over the 20-100k span.
Instaed of going 100 miles an hour, you added a govenor and now can only go 10mph, when you could really go 100mph.

[multieagle]

Thanks Sven. However, for a dedicated small gold machine, would 10K be sufficient? I might add, I will change R25 from 15k to 5k1.

[SVEN1]

Couldn't tell ya, haven't built or looked at the Surf for years

[Hayden]

In another life (before retirement) I was a broadcast engineer. We used to have a saying "If it ain't broke, don't fix it!" I had 33 old computers networked one time. New Cheif engineer insisted on installing EVERY new software update that Gates could come up with. After having to wipe the drives and reload for about the 10th time I finally said "boss, you load up another "update" to that network you better be prepaired to fix the problems it causes yourself!"

If I got a detector that is working, with decent depth and everything is going along just fine, the last thing I am going to do is start changing parts to make it "better" as that just might make it dead Wait until "the lord calls it home" then work on it. You do realize that parts are sold to distributors that are 60%, 80%, 90%, and 99%. That means that 40%, 20%, 10% and 1% are guaranteed to be bad right out of the box! Your supplier likes to go cheap, you got a 4 in 10 chance that new part is DOA! You boys ever deal with ECG or NTE? Then you should know