TGSL Tuning & troubleshooting

[satdaveuk]

The eduardo/silverdog model seems to be the latest version to get some buzz, slight changes to the Audio amp section and gain/filter parameters. There may be some rationale to the layout also, putting the speaker ground closer to the power supply ground point. But dfbowers feels the changes to the gain/filter parameters makes it a little too tempermental in the field. It might be ideal to use the resistors from the original schematic (check the LM358, LM308 op amps) with eduardo's pcb. See this post for changes and comments by dfbowers: http://www.geotech1.com/forums/showp...postcount=4525

Otherwise, you can't go wrong with Ivconic's layout, dfbowers has made some beautiful MDs that work great with it.

-SB

Thanks Simon your a star
Regards

[simonbaker]

Hi
Im due to start the project next week starting with the circuit board
Is there any more update circuit plus pcb layout on here than I aready have for the light, because ive been reading through the threads and there seems to be alot of modifcations been done since I last read the thread, infact you have all been hard at it.
Hope the coil spec has remained the same, If not be kind and tell me that also
I just gone out and bought a new printer because my other one conked out.
Anyway the quicker I get mine built the quicker I can join in the fun with tests etc and scratch what little hair i have left out my head.

Thanks in advance Dave

The eduardo/silverdog model seems to be the latest version to get some buzz, slight changes to the Audio amp section and gain/filter parameters. There may be some rationale to the layout also, putting the speaker ground closer to the power supply ground point. But dfbowers feels the changes to the gain/filter parameters makes it a little too tempermental in the field. It might be ideal to use the resistors from the original schematic (check the LM358, LM308 op amps) with eduardo's pcb. See this post for changes and comments by dfbowers: http://www.geotech1.com/forums/showp...postcount=4525

Otherwise, you can't go wrong with Ivconic's layout, dfbowers has made some beautiful MDs that work great with it.

-SB

[satdaveuk]

THE PROJECT

Hi
Im due to start the project next week starting with the circuit board
Is there any more update circuit plus pcb layout on here than I aready have for the light, because ive been reading through the threads and there seems to be alot of modifcations been done since I last read the thread, infact you have all been hard at it.
Hope the coil spec has remained the same, If not be kind and tell me that also
I just gone out and bought a new printer because my other one conked out.
Anyway the quicker I get mine built the quicker I can join in the fun with tests etc and scratch what little hair i have left out my head.

Thanks in advance Dave

[raff33]

You can easily flip your image with "Paint" or "Microsoft Office picture manager" before printing .. Probably many other ways as well.

Don[/quote]
hi,
it is ok i did many thanks

[dfbowers]

Hi Jerry , dfbowers
i use the "toner transfer method" i tryed to invert the image without result thanks for reply............

[/quote]


You can easily flip your image with "Paint" or "Microsoft Office picture manager" before printing .. Probably many other ways as well.

Don

[raff33]

Hi Jerry , dfbowers
i use the "toner transfer method" i tryed to invert the image without result thanks for reply............[/quote]

[raff33]

What method did you use to make the board?

I used photo sensitive pc boards and exposed them using a transparency that I printed on my ink jet printer. It was a contact print with the transparency so all I did was turn it over so it looked like the pictures.

Jerry

Hi Jerry ,dfbowers
i use the "toner transfer method" i tryed to invert the image without result thanks for reply............

[Jerry]

What method did you use to make the board?

I used photo sensitive pc boards and exposed them using a transparency that I printed on my ink jet printer. It was a contact print with the transparency so all I did was turn it over so it looked like the pictures.

Jerry

[dfbowers]

hi ,
please what's hapen with my pcb why it is inverted ?
'' TGSL complete details "
http://www.geotech1.com/forums/showthread.php?t=15710

Yes, I have made that mistake too. It depends what method you use to make your PCB. If you use the "toner transfer method" you may have to flip the image on your computer before printing. Other methods do not. . I will hopefuly only ever make that mistake once!

Other things to be aware of. Make sure that your image is the correct size. I had to adjust mine to about 108% to get it to the right size. All depends..

Oh well, you just got some good practice for your next one!!

Don

[raff33]

My sensitivity control causes instability at maximum gain but if I back if off until stable, (about a quarter turn) I get good results. For my particular board the mod probably was not needed. I am going to leave it because I did make some parts substitutions and want to change out a few of those to observe changes.

I am using an aluminum box but have the top cover removed most of the time for testing. It seems like there may be a slight improvement with all the covers in place but have not run an actual test with and without.

I hope to finish my vacume forming setup this week.

Jerry

hi ,
please what's hapen with my pcb why it is inverted ?
'' TGSL complete details "

http://www.geotech1.com/forums/showthread.php?t=15710

[Jerry]

My sensitivity control causes instability at maximum gain but if I back if off until stable, (about a quarter turn) I get good results. For my particular board the mod probably was not needed. I am going to leave it because I did make some parts substitutions and want to change out a few of those to observe changes.

I am using an aluminum box but have the top cover removed most of the time for testing. It seems like there may be a slight improvement with all the covers in place but have not run an actual test with and without.

I hope to finish my vacume forming setup this week.

Jerry

[Mullihaka]

Strange, the device is stable at any position of the sens pot; no chatter at all.

I don't know if that's OK or just another sign of something being wrong.

I will make another set of coils using the rescue blanket (or whatever it is) as shielding. In addition, I'll move the device from plastic box to aluminium one. I think they may play some role in getting more depth.

Andy

[Jerry]

That is great news. You are getting close.

The weather has been so nice here (Northern Wisconsin) that I have not been doing a lot with the TGSL. As soon as it turns bad, I will be back at it.

One question: How far can you turn the sensitivity up before it starts crackling?

Jerry

[Mullihaka]

Found the depth problem!

When making the dwbowers mod to the sensitivity pot, I found out that the pot was broken. The voltage at pot viper never went below 6 volts. There was a crack in the carbon arc.

Without the mod I got 23 cm, with mod 26 cm. That's in the middle of the noise from a dozen of instruments.

I'll pack it and get some fresh air, finally!

[Jerry]

Hi Andy:

What do your tx and rx coils measure for inductance and resistance? Can you post some pictures of what the scope is showing when you set your null? So far I have made two coils. One very bad and the other very good. The first one (25 cm) was made last winter and was not real close on inductance or resistance. I had a lot of problems with GB and finally gave up on it but not until I saw some real potential. I was seeing responses to coins at the outputs of U104 & 5 well past 30 cm. It just was chattering all the time and I could not get it ground balanced.

This summer I made a smaller coil. (20 cm) This one measures 5.79 Mh Tx and 6.23 Mh Rx with the resistance about 24 ohms. This coil has worked well from the start. I get about 35 cm on a 2 Euro coin. At 30 Cm it is really solid.

My circuit is from the information that Ivconic provided and I have made several substitutions for parts. So it isnt a real critical circuit to get working. This the background on what I have build with good results, so I know it can be done.

Good luck with your project. Keep us posted on you progress.

Jerry