Magnet Wire for Minipulse Plus Coil Question?

[Fozzy The Bear]

Hi Guys! Can anybody tell me if 0.3mm enamelled copper magnet wire is too thin to wind a coil for the Minipulse Plus ?? I only ask because I have some on hand and it would be good to find a use for it. Otherwise I'll have to use something else.

I also have some 0.7mm stranded copper wire that has a PVC insulation on it making the outer diameter 1.2mm. Would this be better?? and If I use this instead, could somebody explain for me, how I plug the numbers into the coil calculator please, as I don't understand what I need to put in there, given that the insulation is effectively moving the wires further apart in the coil pack.

Best Regards,
Julian.

[baum7154]

The 0.3mm enameled copper, AKA 28awg, would not be my first choice with a resistance of 6.5 ohms per 100 feet and its very thin enamel insulation that results in high inter-wire capacitance in the coil. Really though it depends on what kind/size of coil you are winding and the type of targets it is intended to detect. Where will you be using the detector, perhaps only at the beach? These questions will help to define how good of a coil you should build.

The 0.7mm is 21awg and has a resistance of about 1.28 ohms per hundred feet. While this is a bit larger wire than I would use its thicker PVC insulation is much better than enamel for low capacitance if you want to build a fast coil. However there is a penalty for that larger conductor as it too contributes to greater inter-wire capacitance in a coil. Coil capacitance is the enemy of coil speed.

Are you winding a bunch wound coil to detect large targets like coins or are you trying to detect small gold nuggets? If this coil is just to try out your new detector the larger should be just fine. If you are trying to detect small gold nuggets I would not use either of these wires. I would use stranded 24 or 26 awg PTFE (TEFLON) 600 volt insulated wire wound as a 3DSS coil as detailed in the CHANCE PI COIL thread of the COILS forum.

Regards,

Dan

[Fozzy The Bear]

Thank you for your reply Dan,
Yes mostly beach detecting.. I live in Cornwall in the UK. We have beaches on 3 sides of us within at most about 7 miles, closest one about 2 miles. As for objects... not really gold nugget hunting, so yes coin sized objects and up mostly. Some field detecting. Again mostly coin size objects. Just winding a jumble wound bunch coil for now, just to test the detector and get started with. I'll probably go for building a few different coil types eventually to see what works best for me.

I guess the answer then is go for the 0.7mm for now.... but I still don't understand what numbers to plug into the coil calculator and specifically how the wire insulation thickness needs to be handled in there.

Best Regards,
Julian.

[Qiaozhi]

Thank you for your reply Dan,
Yes mostly beach detecting.. I live in Cornwall in the UK. We have beaches on 3 sides of us within at most about 7 miles, closest one about 2 miles. As for objects... not really gold nugget hunting, so yes coin sized objects and up mostly. Some field detecting. Again mostly coin size objects. Just winding a jumble wound bunch coil for now, just to test the detector and get started with. I'll probably go for building a few different coil types eventually to see what works best for me.

I guess the answer then is go for the 0.7mm for now.... but I still don't understand what numbers to plug into the coil calculator and specifically how the wire insulation thickness needs to be handled in there.

Best Regards,
Julian.

The equations do not take account of insulation versus wire thickness, so I would enter the wire diameter including the insulation. The result is usually close enough. For a 10" diameter former with 0.7mm wire, I would suggest 20 turns for a 300uH coil.

[Fozzy The Bear]

The equations do not take account of insulation versus wire thickness, so I would enter the wire diameter including the insulation. The result is usually close enough. For a 10" diameter former with 0.7mm wire, I would suggest 20 turns for a 300uH coil.

Excellent!! Many thanks yet again for your help with this. Perfect answer, exactly what I needed to know. As the designer of this kit, you certainly take care of the people working with it. Superb kit, superb response and support. Both yourself and Silverdog should be proud of what you achieve that is benefiting other people.

Best regards,
Julian.