TESORO GOLDEN SABRE

[simonbaker]

The question what should be a 'normal' noise level for TGS kept haunting me so I took my stuff and went to my testing ground in the middle of the meadows just outside of my city.
No sheep this time ...

Here's a graph measured on the outputs of the LM308's .

Normally I've only measured the noise on one of the outputs just because I can clip my probe easy on it and in the assumption that the noise level would be the same on both outputs .... not .
I've never expected such a difference between both channel .


Noise on the outputs of the LM308's with a shielded coil in AM mode:


Green for the output of the GB channel and Red for AM/ DISC channel

[ATTACH]15421[/ATTACH]


Noise on the outputs of the LM308's with a shielded coil in DISC mode:

Green for the output of the GB channel and Red for AM/ DISC channel

[ATTACH]15422[/ATTACH]

Now I for sure that :

-The noise level should be very low , 5 -10 mV in the field , but I never achieved this in my workshop which is usualy somewhere between 25/30 mV till skyhigh , with even spikes running trough and really unpredictable.

- My pcb doesn't generate any noise

But why such big difference between the two channels , something must have damaged on my pcb during the trip .

I've switched the LM308's but the problem remained on the same place

Back to workbanch for further investigations ...

This must also explain why some of us suffer from cracks , hums and fals alarms in 'rest' position( due to excessive noise : I think the treshold before alarming is around the 40 mV )

To be continued

Kind regards ,

Dennis the Mennis

Hi DtM:

You are putting us to shame with your excellent use of laptop oscilloscope -- good stuff. I wish I had similar results from my mountain trips to compare. Maybe dfbowers can give you basement readings of noise.

Something does seem strange with GB noise -- it is normal for target signal to be much smaller in that channel, but I think noise should be similar to Disc channel.

Check the voltage on capacitor C12, is it above -.5 Volts?

Is the GB sync pulse pulling high enough (up to ground)?

A poor JFet TR5 is something to check.

Use your probe to check the noise at output of both LM358 U103a,b -- do you see the same comparison?

If you have a low frequency signal generator (5 Hz), you can put it on inputs of LM358 u103 and make sure the gain for GB is same as for DISC in the op amps (LM358 and LM308 ).

-SB

[Hornbuckle]

Hi all, the answer to my question. in the picture below, which marked in green to solder in to v3? and what contacts I have marked in purple....And yet, where there should be at the circuit capacitor, 10pF and 15pF
thanks...
http://imageshack.us/photo/my-images/818/123ca.jpg

[dfbowers]

TGSL 101!

I have been making some progress on writing a "TGSL for Dummies" manual . Here it is for review! Anyone that has some time, please let me know your thoughts for improvement.

I need suggestions for:
- Additions
- Corrections
- Deletions
- General formatting
- Content in general
- Understanding from the viewpoint of the novice

Plus.. I may be competely off base on my understanding of some concepts!

But, one thing I might ask. I have a specific goal in mind, stated on the first page. I will not entertain any ideas if not in line with my goal statement. AND.. this is TGSL 101. Two hundred level is probably next winters project.

Don

[Jerry]

Just finished reading both documents. Terrific Job on a huge undertaking. Thank you for doing this.

Jerry

[Thomas]

This dummie is glad you did this, I read both, but I am going to need to read them a few more times. The pictures helped alot! Thanks for answering many of the questions I've been wondering about, but now I have a whole new set of questions to figure out.

[dfbowers]

This dummie is glad you did this, I read both, but I am going to need to read them a few more times. The pictures helped alot! Thanks for answering many of the questions I've been wondering about, but now I have a whole new set of questions to figure out.

Questions are good!! This is just a draft as I have a few sections to work on yet and some cleaning up to do.

What I really need is for someone to read this that has not attempted to build one yet and let me know what parts are not clear. I'm sure that I have some gaps to fill.

[Thomas]

What I really need is for someone to read this that has not attempted to build one yet and let me know what parts are not clear. I'm sure that I have some gaps to fill.

That would be me, one thing that would be a help to me would be if the functional blocks were closer to each explanation of that block, by the time I find the block, the dummie forgot what he was looking for. I am able to understand what each block is for, but when you say something like, "So in order for the diode D12 to stop conducting (and ultimately
provide forward bias for TR2 in block 13), BOTH U106 Pin1 and 7 must go high at the same
time"...The dummie looks for block 13 and what was that I was looking for? It is one way I can solidify all the blocks together, Its probably not a problem for others, but the dummie has arrived.

[simonbaker]

I have been making some progress on writing a "TGSL for Dummies" manual . Here it is for review! Anyone that has some time, please let me know your thoughts for improvement.

I need suggestions for:
- Additions
- Corrections
- Deletions
- General formatting
- Content in general
- Understanding from the viewpoint of the novice

Plus.. I may be competely off base on my understanding of some concepts!

But, one thing I might ask. I have a specific goal in mind, stated on the first page. I will not entertain any ideas if not in line with my goal statement. AND.. this is TGSL 101. Two hundred level is probably next winters project.

Don

So that's what you've been up to Don!

Man, what a nice job, showing all the functional modules! Anyone coming to this forum will have a real crash course in the TGSL and much better odds of completing the project. Very nice gift to all of us. And I know Danny Dennis the Mennis is putting a labor of love into a similar project. Thanks to both of you (and heck, to everyone who contributes to these forums and into Don's opus).

I like the way you managed to communicate the ideas economically and make the points clear -- I'll need to read some more to really appreciate.

I don't quite get this point though:

6. U103a and U103b further amplify and filter our D.C. phase related signals. Also a

very interesting function is to provide an automatic “threshold” reference value by the voltage retained on C14 and C17. As U103 pin 5 (all metal) and U103 pin 2 (disc) vary, pins 2 and 6 remain nearly the same. U103a and U103b compares and amplifies these differences.

I just thought of it as a kind of bandpass filter, but I'll think about it some.

Thanks for super resource!

-SB

[satdaveuk]

Hi everyone
I must be the last person on here to be making one of these I got the board done , mounted alot of components, I been looking for BF247A, apart from J107 does anyone know of any other fets that will do the job as they were discontinued years ago, and the only sources are exspensive.
Many thanks in advance

[satdaveuk]

I have been making some progress on writing a "TGSL for Dummies" manual . Here it is for review! Anyone that has some time, please let me know your thoughts for improvement.

I need suggestions for:
- Additions
- Corrections
- Deletions
- General formatting
- Content in general
- Understanding from the viewpoint of the novice

Plus.. I may be competely off base on my understanding of some concepts!

But, one thing I might ask. I have a specific goal in mind, stated on the first page. I will not entertain any ideas if not in line with my goal statement. AND.. this is TGSL 101. Two hundred level is probably next winters project.

Don

You done a nice job there mate, very profesional
Many thanks

[dfbowers]

So that's what you've been up to Don!

Man, what a nice job, showing all the functional modules! Anyone coming to this forum will have a real crash course in the TGSL and much better odds of completing the project. Very nice gift to all of us. And I know Danny Dennis the Mennis is putting a labor of love into a similar project. Thanks to both of you (and heck, to everyone who contributes to these forums and into Don's opus).

I like the way you managed to communicate the ideas economically and make the points clear -- I'll need to read some more to really appreciate.

I don't quite get this point though:



I just thought of it as a kind of bandpass filter, but I'll think about it some.

Thanks for super resource!

-SB

Actually.. I was hiding in the Bahamas with the wife for a while!!
You may be right about the bandpass filter thingy. Maybe I misused the term "filter"? Let's ponder a bit and maybe I can clarify the explanation.

[mikebg]

Don, Going into the role of Dummy I ask you: "Why these phasor diagrams seem different; why they have different titles; where is the scale of conductivity and how it explains discrimination?"
Here is the correct orientation:
http://en.wikipedia.org/wiki/Complex_plane

[simonbaker]

Don, Going into the role of Dummy I ask you: "Why these phasor diagrams seem different; why they have different titles; where is the scale of conductivity and how it explains discrimination?"
Here is the correct orientation:
http://en.wikipedia.org/wiki/Complex_plane

I think such diagrams are qualitative anyway, just to give a flavor. Actual phase will depend on the frequency you are using, doesn't it? Also it can be misleading to say ferrite has a phase -- it is really phaseless, just amplitude-modulates whatever your null phase is (ref: Qiaozhi) (from a received signal standpoint). I think that's the case. (Well, maybe you can say ferrite is zero phase if you consider it as having its own magnetic field component -- out of my physics depth there).

It would a nice experiment to use a TGSL or modified circuit to actually verify some target phases.

Regards,

-SB

[dfbowers]

Don, Going into the role of Dummy I ask you: "Why these phasor diagrams seem different; why they have different titles; where is the scale of conductivity and how it explains discrimination?"
Here is the correct orientation:
http://en.wikipedia.org/wiki/Complex_plane

I probably should have cleaned up page 22 before posting as that diagram is not accurate. Maybe reuse the one depicted in the original Gifford patent or remove it all together for page 22? I would agree with you that the orientation is not correct on either one.

I will have a go at redrawing the diagram from the Gifford patent.

Thanks for the suggestion.

[dfbowers]

So that's what you've been up to Don!

Man, what a nice job, showing all the functional modules! Anyone coming to this forum will have a real crash course in the TGSL and much better odds of completing the project. Very nice gift to all of us. And I know Danny Dennis the Mennis is putting a labor of love into a similar project. Thanks to both of you (and heck, to everyone who contributes to these forums and into Don's opus).

I like the way you managed to communicate the ideas economically and make the points clear -- I'll need to read some more to really appreciate.

I don't quite get this point though:



I just thought of it as a kind of bandpass filter, but I'll think about it some.

Thanks for super resource!

-SB

Simon,
Back to your response on block #6, I can see where C13, C16, C18 and C21 determine the upper and lower cutoff frequencies thereby creating a "bandpass" filter of sorts. But since the inputs to pins 2 and 5 are not necessarily at 0V, the OPAMPs have to have some reference voltage all the time on pins 2 and 6. You could just replace the 10uF caps with pots and provide a reference voltage but you would be constantly adjusting them to be slightly lower than the DC value on pins 3 and 5.

My take, for example, was that the DC value on pin 6 would always track the voltage on Pin 7 and any change on Pin 5 would be compared to what was on pin 6.. At least until the caps (C14) began to charge or discharge and caught up to the voltage level on pin 7 again.

Are you suggesting that C14 also has a function in the bandpass filter as well?