Re: Extra coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

The original crystal set was made with a 100 T coil with a sliding tap for
tuning. The coil was placed between earth ground and an antenna. A diode in
series witk a high impedance earphone was shunt across the coil. The load
reduced the Q of the coil and caused broad banding. A second version added a
capacitor (variable ) in series with the coil and a seperate output winding
of about 25 turns to the load. This improved the Q and tunability. A later
version added an extra winding between the two. About 75 turns with a 600 pf
capacitor across it forming a parallel tuned circuit between the input coil
and the output coil.The volume encreased enough to drive a high impedance
speaker( no longer made) with enough volume for a small room of people to
hear.The extra tuned coil was connected to nothing,Just a hi-Q coil between
input and output. No one moved the transmitter or the antenna to add volume.
     Robert  H 
> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Thu, 07 Feb 2002 18:32:44 -0700
> To: tesla-at-pupman-dot-com
> Subject: Re: Extra coil
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Thu, 7 Feb 2002 18:53:54 -0700
> 
> Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <m.j.watts-at-massey.ac.nz>
> 
> Hi Robert,
> 
> On 7 Feb 2002, at 12:06, Tesla list wrote:
> 
>> Original poster: "rheidlebaugh by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
>> 
>> Just a thought as you 2 are discussing the extra coil. Before we had a tube
>> radio we had crystal sets that, at best, tuned 2 stations at once with low
>> volume. When we added an extra coil (3 coil system) the volume went up and
>> we tuned only one station at a time. The extra coil increased the total Q
>> and made the tuning narrow. Is it not likely that a similar effect is seen
>> in the TC with the extra coil?  More power going into one frequency band and
>> less power into the unwanted harmonic losses.
>> Robert  H 
> 
> Good question. First question from me: what was the exact arrangement
> of the crystal set before and after the extra coil was added? I
> suggest that in the first case, the load was coupled too tightly to
> the tuned circuit. In the second, the coupling was rendered looser by
> virtue of less total inductance under the influence of the coupling
> loop. Is there any reason that couldn't have been done with the
> single circuit? Presumably, the aerial was the same in both cases so
> no more power was available to the circuit.
> 
> If you are close enough to the transmitter, you can have a
> reasonably good selectivity and run a loudspeaker from a crystal set using
> a single tuned circuit (I live less than mile from several fairly powerful
> radio masts).
> I have single 3" 1:1 resonator hooked to a few feet of wire in
> my study coupled to a bank of LEDs and self-tuned to one of these
> stations. One morning, a lightning strike put this station off air
> and despite the presence of another station right next door to the
> first and with 5x the output, the LEDs were off-air also. The second
> station was still transmitting at full power as verified by another radio
> set BTW.
> 
> With reference to Tesla's circuit operation, things are totally
> different. It is being operated under transient drive conditions with
> a load that's anything but constant. In fact, Qsys varies from
> several hundred before output sparks start flying to somewhere around
> 10 with attached sparks. This is easily seen by monitoring ringdown
> times on an oscilloscope.
> 
> It is true that in the magnifier, Ksys is much less than the 0.6
> coupling constant between the primary and secondary alone. In fact, it is
> easily demonstrated experimentally that a similar Ksys appears in both.
> There is also strong theoretical support for this and in fact, theory gave
> rise to some key measurements which validated the theory. That implies
> that energy transfer times (and hence primary losses) are the same for the
> two systems if the primary systems have the same inductance and
> capacitance.
> 
> I've seen no evidence that a magnifier with an overall K
> identical to a 2-coil system can do better for a given power input under
> spark producing conditions. Under non-output-sparking conditions, both
systems
> exhibit a broadened spectral response while the gap is conducting and in
fact,
> if breakout is prevented, the magnifier can exhibit a greater one than the 2-
> coil system after the gap has extinguished due to the presence of two coupled
> tuned circuits in the secondary/extra coil system.
> 
> Regards,
> malcolm
> 
>>> From: "Tesla list" <tesla-at-pupman-dot-com>
>>> Date: Wed, 06 Feb 2002 18:59:12 -0700
>>> To: tesla-at-pupman-dot-com
>>> Subject: Re: Extra coil
>>> Resent-From: tesla-at-pupman-dot-com
>>> Resent-Date: Wed, 6 Feb 2002 19:14:32 -0700
>>> 
>>> Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>"
>>> <m.j.watts-at-massey.ac.nz>
>>> 
>>> Hi Nele,
>>> I must confess that I share John Feau's view of magnifier
>>> operation. In fact, one of my first measurements on one confirmed
>>> what he said and was previously postulated by Dr de Queiroz, notably
>>> the value of Ksys. I too have read Tesla's notes on this but think
>>> that what he thought and what actually happens are two different
>>> things with respect to this particular form of TC. It is a nice idea
>>> to think that the primary/secondary act like an oscillating voltage
>>> source but in a disruptively-driven system they cannot for two
>>> reasons: K for the pri-sec system is less than 1 and secondly, it is
>>> driven from a charged capacitor (which runs down to empty), not a
>>> voltage source (zero internal impedance generator).
> <snip> 
> 
> 
>