Whites Surf PI schematic

[chemelec]

Easy Enough to do. Replace the Feedback Resistor 1M on NE5534 to a Pot.

Not tried the Motion no Motion mod. It didn't keep the Threshold Tone going any longer ?

Yes I Know it is Easy to add that Gain Control, but why don't they add it in their kits.
Is it useful or not?

[homefire]

??? Don't know. Save the cost of a Pot? LOL It's not like a VLF needing to Tune Down to handle Ground conditions I guess. The Surfs not the deepest of PI so no need to turn down to stop digging 2ft holes for fishing weights ? I have a untouched Silver Dog kit sitting here Idle. I'll put the Pot on just because I can.

[kt315]

you have to use shielded cable for the pot anotherway you get strong unstability.

good luck

[homefire]

Yep, Amplifying tons of Noise on the wire.

[chemelec]

Being Curious, I added in the Gain Control, using No Shielded wire and it added No Noise Problems.
I also found having the Gain control does seem to have some advantages in tuning this detector.
My detector also has a Audio Transformer to better match to speaker impedance.

[homefire]

I be thinking the Noise would only be a issue in a Hight RFI or EMI location. No one seems to Remember that you have to Match Impeadance with Head Phones and Speakers any more. It makes a wHOOPING difference in not only in Volume but Tones and Sounds. Thank You.

[chemelec]

Here is my Schematic.

[kt315]

[ATTACH]38246[/ATTACH] Here is my Schematic.

Replace the Feedback Resistor 1M on NE5534 to a Pot.

seems we say about different things. in YOUR schematic the shielding of pot GAIN is not needed.
i mean FEEDBACK RESISTOR ON FRONT END.

[Old cart]

seems we say about different things. in YOUR schematic the shielding of pot GAIN is not needed.
i mean FEEDBACK RESISTOR ON FRONT END.

Perhaps that is the best place to adjust gain since it is essentially DC at that point. Trying to adjust the first stage gain with a pot is difficult as just a few pF of capacitance can are a difference. Maybe crank the first stage gain down to 500 and increased the D.C. Gain by a favor of 4 and then make it adjustable.
As for the transformer some versions of Surf PI had this very transformer. Does it really improve the sound? Can you make a recording?

[chemelec]

It Definitely gives better and louder sound and will drive a loudspeaker, although headphones are still best to use.

As to the Gain control I added, it is the same as shown in the Original Surf Pro Schematic by White's Electronics Inc.
I also included the frequency control of the 7660 from the 555.


The Only Other Surf I have seen with this transformer is one I also built and posted on here a few years ago.
But Didn't seem anyone was interested in it back than.

Personally I have no use for this Surf Detector, Just built it for fun and to see what difference it would make.
It goes in the garbage after in a few more days of playing with it.

Probably so will all my electronic parts and equipment in about 1 year.

[WM6]

The Only Other Surf I have seen with this transformer is one I also built and posted on here a few years ago.
But Didn't seem anyone was interested in it back than.

Wrong impress, your ideas and circuits solutions are very welcomed and really nice. Thank you.

[chemelec]

Here is a Sound File, Recorded using an old Crystal Mic.
Excuse the Hum, not a very good setup.

[homefire]

Man I'd have to lower that freq. Hurts the Ears.

[chemelec]

Sorry, VERY CHEAP MICROPHONE.
Doesn't sound so high Pitch coming from the speaker.
And Loudness is Good.

[homefire]

Good Stuff.