Re: phase locked loop SSTC

["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>

Luc; The problem is 2n3055. This transistor has a very low base tolerance to
over current or voltage. A RCA 40411 is forgiving of abuse. Yes you can use
a "HARTLEY" oscilator circuit with a feedback winding in a solid state TC
coil.
 Robert  H  

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Fri, 28 Dec 2001 17:13:37 -0700
> To: tesla-at-pupman-dot-com
> Subject: Re: phase locked loop SSTC
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Fri, 28 Dec 2001 17:18:42 -0700
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Kchdlh-at-aol-dot-com>
> 
> In a message dated 12/28/2001 11:15:44 AM Pacific Standard Time,
> tesla-at-pupman-dot-com writes:
> 
> 
>> 
>> Subj:Re: phase locked loop SSTC
>> Date:12/28/2001 11:15:44 AM Pacific Standard Time
>> From:<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com
>> To:<mailto:tesla-at-pupman-dot-com>tesla-at-pupman-dot-com
>> Sent from the Internet
>> 
>> 
>> 
>> Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
>> <ludev-at-videotron.ca>
>> 
>> Hi list,
>> 
>> Could someone here be enough generous to explain in simple term
>> why can't you use a feedback loop like the grid loop in VTTC or
>> the feedback loop used in simple flyback ( 2* 2N3055 circuit )
>> for driving a half bridge mosfet.
>> 
>> I ask this question in many occasion in the last 2 years and I
>> never get an answer. Each time I try to rephrase the question
>> because I know my english could be ambiguous sometime but whit
>> out success.
>> 
>> Cheers,
>> 
>> Luc Benard
>> 
>> Tesla list wrote:
>>> 
>>> Original poster: "Malcolm Watts by way of Terry Fritz
>> <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
>>> 
>>> Hi Paul,
>>> 
>>> On 27 Dec 2001, at 7:49, Tesla list wrote:
>>> 
>>>> Original poster: "Paul Nicholson by way of Terry Fritz
>>> <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>
>>>> 
>>>> John Tomacic wrote:
>>>> 
>>>>> use a current sense transformer in series with the secondary
>>>>> driving the magnifier coil (placed in between the secondary
>>>>> and ground).  The signal from the sense tx should be rectified,
>>>>> filtered then fed to a comparator.  Since maximum current is
>>>>> drawn through the coil at resonance, the frequency of the driver
>>>>> can be adjusted by the comparator through a vco to always keep
>>>>> the coil in resonance.
>>>> 
>>>> I wrote:
>>>> 
>>>>> John, can you help me understand just how the vco is tuned with
>>>>> this arrangement?  I don't see how, with only amplitude info
>>>>> from the sensor, the vco can 'know' which direction to tune, ie up
>>>>> or down?
>>>> 
>>>> Malcolm wrote:
>>>> 
>>>>> A digital approach can pull a "direction" out of the signal (a D FF
>>>>> is all it takes).
>>>> 
>>>> Malcolm,
>>>> 
>>>> Well, I don't understand this. John doesn't seem to be giving any
>>>> hints, maybe you can explain?  How can you tune the VCO with just an
>>>> amplitude feedback and a comparator?
>>> 
>>> If you apply one signal to the "D" input and the other to the clock
>>> input, Q will be high or low depending on relative phasing of the two
>>> signals. I realize that because the frequencies are different, the
>>> phase will slide from lagging to leading (or vice-versa) but if the
>>> difference is not too great, the direction indication should last for
>>> long enough to enable locking. An XOR gate fed from the same signals
>>> gives the degree of difference.
>>> Kind of handwaving stuff from the digital realm but I thought
>>> it might be useful or applicable to the problem.
>>> 
>>> Regards,
>>> Malcolm
>> 
>> Luc
> 
> -
> 
> I haven't been following this discussion, but I see no reason to complicate
> things:  My s.s. system uses simple positive feedback from the secondary's
> return-end to excite its linear amplifier, MOSFET drivers and MOSFET
> assemblies.  The key to doing that, I found, is to phase-shift the voltage
> signal taken from the secondary by ~90 degrees, by connecting the secondary's
> lead to ground via a low-Z capacitor--of 0.15 uF or so in my case.  The
> (small)
> voltage across that capacitor then ends up in phase (or 180 out depending on
> how the primary/secondary windings are phased) with the signal you need to
> drive the MOSFETs, or tubes, or whatever.
> 
> A happy new year to you, & to all...
> 
> Ken Herrick
> 
>