2 box working, but not quite, Coil Q??

[Desert Eagle]

Ok Folks, have got the transmitter portion and the reciver portion of my


2 box done, now to play with coils. The dementions are given for the


coil in the schematic. However, when built to specs I find the f is off


when built to the schematic. By changing capacitors,(trial and error), I


finly get it close, 178hz, but the range and sensitivity is really poor.


I am looking at changing the size of the coils and experamenting with


that,


However, after our last move I can't seam to find my notes and charts


for figuring the dementions of a coil and the capacitance needed to make


it resonate at the desired f. I want to go to about a 12" sq. coil and


also experament with an 18" and 24" coils.


Any help would be gratly appriciated, I had a program at one time that


would do it for me but it has fatal errors in it now and gives bogus


information.


Any help from those out there would be greatly appriciated. My e-mail


will accept up to a 2 meg file and I have pdf read capabilities. Pleas


dont hesitate to e-mail me direct if you want,


[email protected]


Thanks,


Desert Eagle, (AKA) jimi

[Carl]

Re: 2 box working, but not quite, Coil Q??

>By changing capacitors,(trial and error), I finly get it close, 178hz, but the range and sensitivity is really poor.


Jimi, do you really mean 178 Hz? Maybe 17 KHz? What kind of transmit oscillator is it?


- Carl

[Desert Eagle]

Khz

Sorry mised a K in there, 178Khz


>Jimi, do you really mean 178 Hz? Maybe 17 KHz? What kind of transmit oscillator is it?


>- Carl

[Carl]

Re: Khz

>Sorry mised a K in there, 178Khz


178KHz sounds a little high - ground penetration decreases with higher f. Also you might have detuned the circuit depending on the design. If you have a GIF or JPEG image of the schematic you can use the Image Upload entry in the follow-up and post it to the forum. Or email it to me if you prefer.


- Carl

[Desert Eagle]

Re: Khz

Its the same on on your page,


Desert Eagle,

[Carl]

Re: Khz

So when you say you changed the caps until you got 178KHz, is that on the transmit or receive side or both? It sounds like maybe the receiver is not tuned to the right frequency, which will kill the sensitivity.


- Carl