TESORO GOLDEN SABRE

[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

[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

[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.

[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]

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.

[Jerry]

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

Jerry

[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

[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

[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

[Dennis the Mennis]

Noise under field conditions

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




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



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

[simonbaker]

Hi Simon ,
Thanks for your reply ,
To be sure no one gets confused I've made some graphs again of :

- pin 1 vs pin 2 of the LF353 and
- pin 1 LF353 vs LM393 pin 1 (Disc Sync Pulse / all these examples at 0% of disc pot)

for 51 , 68 , 80 , 100 , 122 and 168 pF .

51 pF :

[ATTACH]15411[/ATTACH]

68 pF :

[ATTACH]15412[/ATTACH] [ATTACH]15413[/ATTACH]

80 pF :

[ATTACH]15414[/ATTACH] [ATTACH]15415[/ATTACH]

100 pF :

[ATTACH]15416[/ATTACH] [ATTACH]15417[/ATTACH]

122 pF : ( from 0% -40% of disc pot the spike remains )


[ATTACH]15418[/ATTACH]

168 pF :

[ATTACH]15419[/ATTACH] [ATTACH]15420[/ATTACH]

In my case it is impossible to make a 'perfect sinus' ...

But as said before : the secret of the Disc Sync spikes is revealed ...



I probably will also work in All Metal Mode , but just wanted to have good working pcb just in case ...Thanks for the reminder ( I'm just a rookie )



Stay with us and I will let you know if I get it working ( ever ).
I'm glad it helped you ... We'll get to the bottom of the TGS(L) !!

I must say I didn't experiment enough with the DISC function yet , I wanted to collect the materials which should DISC OUT according a picture I saw of an original TGS : Pulltab ( the new pulltabs are much smaller as the ones which amputate your feet when you step on it ) , Foil ( like you posted but I didn't find the baklava yet here ) , Nickel ( as the alloy or like the coin ? ) and the S.Cap which I don't understand but I think a cap from a beer- or soda bottle .

Perhaps when the spikes are at the end or the beginning of your DISC SYNC you could miss a tiny bit (?), I think the most important is if the DISC SYNC starts at the right point.
So enough questions left

kind regards ,

Dennis the Mennis

Thanks DtM, I can sleep at night again...

Your (actual) LF353 pin 1 looks pretty normal, and those little spikes on the sync pulse usually don't cause a problem (even though I don't like them and made some mods to get rid of them).

I've never seen a graph of LF353 pin 2 before, so... interesting! But generally we don't care what it looks like, if pin 1 looks pretty good. However, it might be useful someday to compare our pin 2's. Because it is a "virtual ground" according to op amp theory, it is hard to interpret (for me).

Anyway, I would think your DISC mode should work OK -- if your sync pulse phase range (min to max) is normal compared to TX signal phase. It looked roughly OK to me, but we can check some more.

I think you already checked this, but it is useful to check the voltage on C15 as the DISC pot is turned from min to max. It should not go below -.5 volts, otherwise could be a problem.

If you have trouble obtaining a US Nickel coin, let me know. I find that coin the easiest to check the discrimination. Maybe dfbowers and others can check where a US Nickel discriminates (what pot setting). I'll check when I get a chance.

Regards,

-SB

[Dennis the Mennis]

Hi DtM - great pics -- raises some interesting questions!

I assume the red traces are the output of LF353 pin1. When I look at the voltage scale, it looks like the signal is approximately 100 mV p-p. Is that correct????? If so, something is really wrong! The output of LF353 pin1 should be 10 volts peak-to-peak at least!

Would you double-check that? Maybe you measured a different point?

I did and you were right ( of course ) , I messed up LF 353 pin1 and pin2 , the other side of the 100K ...
Normally it is pretty late when I post something ... must have been sleepy, my workshop noise usually becomes less after 00:30 hr , don't know why.

Anyway, the sync pulses look good shape, which is what matters. But for good stability, you want a healthy input, so tell us what is happening with the LF353 pin 1 -- something is strange there.

Also, looking at the graphs of the LF353 pin 1, I see many zero crossings that I would expect to make spikes in the sync pulse, so I'm wondering if you probed the correct point? Let us know!

Best regards,

-SB

Hi Simon ,
Thanks for your reply ,
To be sure no one gets confused I've made some graphs again of :

- pin 1 vs pin 2 of the LF353 and
- pin 1 LF353 vs LM393 pin 1 (Disc Sync Pulse / all these examples at 0% of disc pot)

for 51 , 68 , 80 , 100 , 122 and 168 pF .

51 pF :



68 pF :



80 pF :



100 pF :



122 pF : ( from 0% -40% of disc pot the spike remains )




168 pF :



In my case it is impossible to make a 'perfect sinus' ...

But as said before : the secret of the Disc Sync spikes is revealed ...

Trouble is Dennis, if we disc out foil here in england, we loose are old sixpence which is 65% silver, also you and us would miss out on small silver rings etc, so I would advise dig all foil, no matter where in the world you live
My opinion of course
Regards
Dave

I probably will also work in All Metal Mode , but just wanted to have good working pcb just in case ...Thanks for the reminder ( I'm just a rookie )

Hello Dennis!
Glad to hear your disc is working . Im considering to make TGS original so I wish to know about noch. I hope you will get it working

Thanks for all the scope images and results of experiments - its very helpful.
I got spikes too. But say - is your disc becaming worse with spikes? Is there any reason of getting rid of them?

Stay with us and I will let you know if I get it working ( ever ).
I'm glad it helped you ... We'll get to the bottom of the TGS(L) !!

I must say I didn't experiment enough with the DISC function yet , I wanted to collect the materials which should DISC OUT according a picture I saw of an original TGS : Pulltab ( the new pulltabs are much smaller as the ones which amputate your feet when you step on it ) , Foil ( like you posted but I didn't find the baklava yet here ) , Nickel ( as the alloy or like the coin ? ) and the S.Cap which I don't understand but I think a cap from a beer- or soda bottle .

Perhaps when the spikes are at the end or the beginning of your DISC SYNC you could miss a tiny bit (?), I think the most important is if the DISC SYNC starts at the right point.
So enough questions left

kind regards ,

Dennis the Mennis

[simonbaker]

I've did a small test with different C9 values but is seems that within the range of 60 - 90 pF you the 'best' Disc signal/ shape output LM393 pin 1 ( varying of course from pcb to pcb ).


This a picture with 68pF for C9 : Output pin1 LF353 vs output pin1 LM393 DISC signal with Disc pot at minimum / 0% .
Still a little spike, only at the minimum of the disc potmeter

[ATTACH]15376[/ATTACH]

This 80 pF has also the same spike only at the minimum setting for the Disc pot
Only the complete signal at the output LF353 increases.

[ATTACH]15377[/ATTACH]


A 100 pF for C9 gives my pcb the best cards in terms of a Disc signal without any spikes over the complete range of the Disc potmeter ...

[ATTACH]15378[/ATTACH]

122 pF gives spikes again even at 50% of the Disc potmeter

0% :

[ATTACH]15379[/ATTACH]

50% :

[ATTACH]15380[/ATTACH]

and 168 pF : the ringing somewhat disappears

[ATTACH]15381[/ATTACH]

As said before : this part of the circuit is pretty forgiving and if someone has problems with the spikes a different value for C9 mightbe considered .


Kind regards ,

Dennis the Mennis

Hi DtM - great pics -- raises some interesting questions!

I assume the red traces are the output of LF353 pin1. When I look at the voltage scale, it looks like the signal is approximately 100 mV p-p. Is that correct????? If so, something is really wrong! The output of LF353 pin1 should be 10 volts peak-to-peak at least!

Would you double-check that? Maybe you measured a different point?

Anyway, the sync pulses look good shape, which is what matters. But for good stability, you want a healthy input, so tell us what is happening with the LF353 pin 1 -- something is strange there.

Also, looking at the graphs of the LF353 pin 1, I see many zero crossings that I would expect to make spikes in the sync pulse, so I'm wondering if you probed the correct point? Let us know!

Best regards,

-SB

[habitbraker]

Hi Habitbraker ,

I think my Disc function is working finally, still experimenting with it to be sure ...

I haven't tried the notch function that much because I think it doesn't work at the moment.

I recently discovered some defective parts on my pcb causing a not working Disc function for a long so I didn't spend that much time on the Disc ...

Now I can Disc out a piece of chewing gum foil and still detect a coin at the same time.


kind regards ,

Dennis the Mennis

Hello Dennis!
Glad to hear your disc is working . Im considering to make TGS original so I wish to know about noch. I hope you will get it working

Thanks for all the scope images and results of experiments - its very helpful.
I got spikes too. But say - is your disc becaming worse with spikes? Is there any reason of getting rid of them?

[satdaveuk]

foil

Hi Habitbraker ,

I think my Disc function is working finally, still experimenting with it to be sure ...

I haven't tried the notch function that much because I think it doesn't work at the moment.

I recently discovered some defective parts on my pcb causing a not working Disc function for a long so I didn't spend that much time on the Disc ...

Now I can Disc out a piece of chewing gum foil and still detect a coin at the same time.


kind regards ,

Dennis the Mennis

Trouble is Dennis, if we disc out foil here in england, we loose are old sixpence which is 65% silver, also you and us would miss out on small silver rings etc, so I would advise dig all foil, no matter where in the world you live
My opinion of course
Regards
Dave