Dr Ronald Stiffler SEC technology

[gyulasun]

Yes, you can use it.   Thanks for the DC voltage values.   Did you find any mV in AC voltage mode? I know that voltage meters are useful at 50-60 Hz sinusoidal frequencies but some ten mV to some 100 mV indication in AC mode could be expected from them if the oscillator works. Compare the AC voltages when the crystal is removed versus when in place.

[erfandl]

Yes, you can use it.   Thanks for the DC voltage values.   Did you find any mV in AC voltage mode? I know that voltage meters are useful at 50-60 Hz sinusoidal frequencies but some ten mV to some 100 mV indication in AC mode could be expected from them if the oscillator works. Compare the AC voltages when the crystal is removed versus when in place.

thanks. I used that 1000 uh coil. the AC voltage from supply ground and tesla coil about 7 volt and frequency is 900 hertz.
I build the below circuit and its working like a charm with tesla musical coil. but I dont know why the crystal circuit cannot be working

[gyulasun]

Well, please do not connect the air coil to the collector of the crystal oscillator circuit, ok? Just check the AC voltage between the negative ground and the base and between the negative ground and collector, first without the crystal and then with the crystal in place,  ok? Check this with the 1 kOhm resistor too and also with the 1000 uH choke instead of the 1 kOhm.

Your mesured DC voltage of 0.675 V between the base and emitter that is correct and the collector voltage of 2.35 V versus the emitter is also good when the 1 kOhm collector resistance is used but ideally 6 V DC would be the best value there if your supply voltage is 12 V. You could use a 470 kOhm trimmer potmeter (or a 220 kOhm in series with the 100 kOhm resistor) to adjust the 6 V DC between the collector-emitter when the crystal and the coil is removed and you have the 1 kOhm collector resistor instead of the choke coil. The 6 V DC level would insure the transistor is biased for the most linear operational point and oscillating signal would have the least distortion.

You do not have a oscilloscope but a digital multimeter, is this so?  Do you have a function or signal generator, even with a low level output?

[Lidmotor]

 :DAll ---I did a video explaining this crystal circuit exciter build better and specifically how I am making that air core coil.  I just wrap stiff paper on a AA battery, wrap the length of the battery with 26ga magnet wire, take the battery out,  and that is it.  I don't count the turns or measure the inductance.  A ferrite rod moved in and out does the fine tuning.  The coil is based on Dr. Stiffler's SEC 18 'L3' but is longer. 
  I soldered up a replication of the initial bread board version taking care to put the components on the board in about the same location.  It worked fine but the device is sensitive capacitive influence.  Tuning is a bit touchy. 
   I show the second unit driving the first unit wirelessly here:
   
  https://www.youtube.com/watch?v=tJhdZNIUOiI

Cheers,
            Lidmotor

PS----Gyula I think your idea about using a 'wiper' style coil for tuning like in a simple Crystal Radio might work.  I might try that today.  As far as the 1000mh choke I did get mine to run on different values and styles so building your own should not be a problem.  The dynamic of these open ended exciters goes beyond a simple running oscillator and EVERTHING in the local area has some effect on it -- including the human sitting in front of it.  The types of components and their position in relationship to each other matter.  I was very worried that I was not going to replicate my original bread board setup because of the capacitance in the bread board itself.  I got lucky.  It is like all the things in the local are talking to one  other when the thing pops into resonance.  In the above video I could tune the whole area in and out of resonance but tuning the second unit that was driving the pulse motor.

[erfandl]

Well, please do not connect the air coil to the collector of the crystal oscillator circuit, ok? Just check the AC voltage between the negative ground and the base and between the negative ground and collector, first without the crystal and then with the crystal in place,  ok? Check this with the 1 kOhm resistor too and also with the 1000 uH choke instead of the 1 kOhm.

Your mesured DC voltage of 0.675 V between the base and emitter that is correct and the collector voltage of 2.35 V versus the emitter is also good when the 1 kOhm collector resistance is used but ideally 6 V DC would be the best value there if your supply voltage is 12 V. You could use a 470 kOhm trimmer potmeter (or a 220 kOhm in series with the 100 kOhm resistor) to adjust the 6 V DC between the collector-emitter when the crystal and the coil is removed and you have the 1 kOhm collector resistor instead of the choke coil. The 6 V DC level would insure the transistor is biased for the most linear operational point and oscillating signal would have the least distortion.

You do not have a oscilloscope but a digital multimeter, is this so?  Do you have a function or signal generator, even with a low level output?

thanks so much for reply. OK . no I don't have oscilloscope and signal generator or function
the AC voltage report:

0.018 base voltage with 1000 uh and with crystal
0.476  colector voltage with 1000 uh and with crystal
0 base voltage with 1000 uh and no crystal
0.476 colector voltage with 1000 uh and no crystal ( the voltage randomly go to 0.000 and go to 0.476 )

0 base voltage with 1kohm resistor and with crystal
0.004 collector voltage with 1kohm and with crystal
0 base voltage with 1kohm resistor and no crystal
0 collector voltage with 1kohm resistor and no crystal