The coil inductance is determined by this formulas
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg7oBz8uZiLvC8GPSc4AOFEOwDAsuKMwf7X_7FRkp6eiaEP1SdCANMCVXz0W90QLW70hHb-NuET0-7o4RyXnXgOAAdoA63bpK0N18OckA7G8VlFMqqi3H_12jXR2I5kcFPu0e19YRIBVEM/s320/Turns+to+make+coil+Coil.jpg)
The factor are length of winding and radius of the windings. K is found from a chart.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhraRccXWg-CPOFDuuvdyamfZ71XxN3At8hxrrdW-P4s_9_w4m62kxs2jnFyZERsba4u9L3zgk189ZFF8LBx7C-0O_htoDs9MPMp9SHW1e00SwzNhJRf81EiwZOd644FYHROXUaxZJPLNI/s640/Table+K+factor.jpg)
The Diameter to Length ratio is calculated and then the K is found on the chart. The inductance to resistance ratio is the Q so a larger wire with less resistance or a shorter wire of smaller gauge will give different results. For the rule of thumb a 'square' coil will be the best compromise. There are to many variables to just go square though. For example a transmitter coil may be wound with 1/4" copper tubing.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi13vEwRzavIl9Fu0BwpG5TnsTjTSYM455X2S8A8PCsFPLJCaLHzfwjxzAFrt0vAXpLfS9rH4s9uAXh5IJYAFQ2OI9vkzgPbj-i3A6ToFnbxPUvBI-D5_zdOXo0rsphku1Fx_KgQpANBQ8/s640/spacing+turns.jpg)
This example shows the 'square' coil has more inductance with the same size and number of turns the wire resistance will be the same and the Q will be higher for the 'square' coil. However if the 'square'coil was a receiver coil wound with 24 guage wire and the other coil was a transmitter coil wound with 1/4" copper tubing it could have a high Q so they could both serve their purpose. You could use this chart to find your values.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEipIfwrQyy_gqD6tMZFNeSQ_FBpBL9K-ja_AAcywIOkO9fRR8eWJPdLNP_N8zgIwE2Vu1phQfJp2sCKaUEGf7zcyCv1QuNbvXj647GVOsOQUU6icv8gmF_xRx_rfIZn8D38Od1cACdGVDw/s1600/LC+chart.jpg)
Then determine the Q you want and use this chart to see some posibilities.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg6mDOSJdSc9dywrJg4nNpWVfk17HeyrmS2TGtzWrkA6uEBTG0zNW9SerLK3bxsBslPcDUBYAsMTuvXSBJY1Tl7qFsTwXdjSFOQlcEP215bx_BYx1r_aRREJ33zroBrWLR3sIoTZmYn1KM/s640/former+size.jpg)
The chart shows a larger diameter coil is higher Q.
For more information including spider wound coils check this link
Comparing different coil types
No comments:
Post a Comment