Surf Pi Post assembly checks?

[silverdog]

Yep, twas me that found it, if you recall!!!! (Took me 2 weeks to find it, though, I am ashamed to admit!!!)

I have found that different coils cause 'hiccups' in the delay setting, I'm sure I will hit an optimum coil inductance soon,...... looking around 400 to 500 microhenrys at the mo...........

LOL!!! Cheers, Fred

Just picked this up one bay for £22
measures 240uH

[Lefizz]

Now I am jealous

What kind of results can you get with it attached to one of your kits?

What diameter is it?

[homefire]

I have that coil stuck away some place . Need to dig it out. Thanks for the Measurement.

[Lefizz]

So i built a 260mm coil today, to what it would perform like. Seems to give me about another inch or two. Its weird the faint signal is better with this, i get weak signals even further away but a strongish signal (not solid tone) is around 1.5 inch further but weak but repeatable signals are probably another 1.5 inch on that.

Seem like a step forward to me, plus i had less time to test tonight (where eagles dare was on the box). I will do more tuning over the weekend to see what more i can scrape out of it.

I read somewhere that tuning one of the resistors can help, which is it?

Regards Phil

[Lefizz]

Any news Comp?

Did you build a bigger coil?

[Comp]

Any news Comp?

Did you build a bigger coil?

Hiya!!! Nope!! the love of my life found me a couple of chores to do on my day off,.... (to be fair, the hinges on the front door failed, and seemed to be more important than winding a coil,.... )
and have been at work this morning as well,... but I have just finished winding a 25 turn, 270cm coil, I have bound and glued it,... but not shielded yet,... I think I will try it tomorrow, and post back.....

Cheers, Fred

Edited to add....... I do think trying to get 40cm airdepth test on a, say 1 Euro coin with a 20cm coil is probably a bit hopeful..... I have looked at the tests on YouTube, and wound a fair number of coils, but struggled to get more than 25cm airtest depth with any of them, scramble wound, basketweave, whatever... as it is my first play with a MD, I didn't know what to expect,.... and the videos led me to think 35 to 40 cm would be easily achievable,... now, I am not so sure,......

I have stripped, & tested bits from my board so often, the print is shot it, and had to order a spare board to rebuild up!!!!
It would be nice to have an airtest guide for the Surf, for us newbies,.... I'll start the ball rolling, I can test a Euro at 20cm, with a 20 cm coil easy. A baked bean tin at nearly double that, and a Quality Street sweet tin from Xmas at about 50 cm.

I will post results of the new coil ASAP, when tested, and I plan on tweaking the damping resistor. The coil pulse width has been tweaked to about 70 microsecs at the mo, by increasing R2 to 4K7.

[Comp]

Ok, Update,.. I wound a 27cm coil, 25 turns of 24swg enamelled wire,... came in at 2.6 ohms dc resistance, 506 microHenrys inductance,......bound and superglued,....

Air tests were,.. a 1 Euro coin, 27 cms, my gold wedding ring, (24mms dia) 32cms,.. I didn't have a bean tin, but did have an aerosol, (PCB cleaner) similar size, 53cms,.....

Not brill, but a lot better than the 20 cms coils,.... time to pot it up, and go look for gold!!!!

Cheers all, Fred

[Lefizz]

Ok here are my results on my homemade 27cm 19turn 30awg coil.

1 euro......... 29cm

Baked Bean tine (ok tomate frit...you try and find bean in Spain)...55cm

Gold Ring......no idea my missus is wearing it in London at the moment

Results defintely seemed to go up once I shielded the coil.

I used a USB2 extension cable as my main cable that way you can cut it and get a coil lead and the plug an socket you need all it one. It cost 1.50 euro, what a deal.

Are results look very similar Fred, seeing as i dont have a scope I am really happy with that.