TGSL-EDU Build Question

[Agme]

I am building a TGSL-EDU and had a question regarding a capacitor. When I was completing my BOM for the components I missed this 100uF capacitor between the 8V and -5V. Can I substitute a 220uF Instead of 100uF? Or just omit it (its not on the TSGL schematic)? It seems like this it just for filtering and the value shouldn't matter, but I wanted to ask just to be sure there wasn't some hidden purpose.




Thanks

[Carl-NC]

Yes, value isn't critical.

[Agme]

Thank you!

[rajesh]

Thank you!

[Agme]

DD Coil Winding Direction and overlap question.

I have a couple of questions regarding the building of the DD coil.

1) How should the winding direction of the coils be arranged? Should they be in the same direction or opposed (see pictures). And does the direction matter in relation to the ground? The TGSLcoil document says wound in the same direction, but I just want to confirm.
2) Which coil should be on bottom (closest to the ground) when they (TX/RX) cross? Does it matter?

I have read thru the 101 document, the "TGSLCoil Making" making document, the ITMD book, and the forum and I didn't find a clear answer. I'm sorry if I missed this somewhere.




Thanks for any advise!

[Agme]

DD Coil Winding / Coil Winder and Coil Measurements

I'm just going to start putting this stuff here. I don't want to extend the already very long TGSL posts. I am just going to document my TGSL Build with pictures and measurements. Maybe it will help someone / maybe not.

This was my approach to winding the coils and the frequency response for each stage. My crappy LCR meter was not accurate so I based everything off of the frequency of the coil using TGSL and used the colpits equation to get the Inductance (for reference)

For the most part I followed the 101 document, the only thing I did a little different is after 1 terrible try to tie the string I decided to use small zipties 1st then tie the string and glue. I also realized too late that if I put the string wraps directly over the dowels (put the string between the dowels and wire) it prevents the little divots in the wire form.

[Agme]

TGSL-EDU BOM - Parts List

This is the BOM I put together. The parts are from Tayda. Use at your own risk. The text file is a CSV.

TGSL-EDU-FINAL.txt
TGSL-EDU-FINAL.pdf


The forum was incredibly confusing about which opamps are better. I listed all of them I saw mentioned in the main TGSL post, I bought all of them. I plan on experimenting to see if there is any noticeable differences.

[MartyJ1963]

Nice one Agme! I'll be following this thread to see how you progress. Best luck in your build. Regards, Marty.

[Agme]

This is the BOM I put together. The parts are from Tayda. Use at your own risk. The text file is a CSV.

[ATTACH]56019[/ATTACH]
[ATTACH]56021[/ATTACH]


The forum was incredibly confusing about which opamps are better. I listed all of them I saw mentioned in the main TGSL post, I bought all of them. I plan on experimenting to see if there is any noticeable differences.

I should not have posted this yet.. I was going thru the pinouts and some of the ICs are wrong (the Substitutes/Options) I will post again when I'm finished.

[waltr]

Agme,
Coil winds are both in same direction.
It is when you look to Null the coil with a 2 channel O'scope you can check this. The Phase of RX should be close to the TX phase. If near 180 degrees off then swap the leads on one coil.

Your coil form looks nice. I make a form like that. I then waxed the form as a release agent and coated the wired as it was being wound with Polyurethane. This glues the wires together so no tie wraps are needed and the coil holds it shape.

[Agme]

Agme,
Coil winds are both in same direction.
It is when you look to Null the coil with a 2 channel O'scope you can check this. The Phase of RX should be close to the TX phase. If near 180 degrees off then swap the leads on one coil.

Your coil form looks nice. I make a form like that. I then waxed the form as a release agent and coated the wired as it was being wound with Polyurethane. This glues the wires together so no tie wraps are needed and the coil holds it shape.

Thanks!
Do know if it makes any difference which coil is closer to the ground (TX or RX)?

The string and gluing is the worst part. I will try the poly. Thanks for the tip. Are you using just regular paraffin wax or something like a fiberglass mold release wax?

[waltr]

Don't think it matters which is closer, both are less than a cm difference.

I used paraffin since it what I had. A good mold release should also work if the wood surface is sealed (the wax rubbed on does this).
Do a test for a piece of wood like used on your form. Then you will know.