Partnered Output Coils - Free Energy

[gyulasun]

A blocking oscillator?
Nice name, but what actually is blocked?.
Current path diversion oscillator would be a better description.
....

Hi Brad,

Just for the shake of correct technical info, the name 'blocking' oscillator was created in the era when sweep circuits were developed for television receivers. 'Blocking' was meant to cut the plate current off by applying a sudden high negative bias voltage on the grid of an electric valve.
In television receivers there have been a horizontal and a vertical oscillator to insure that the position control of electron beam (thinking of cathode ray tubes) should be from left to right and from up to down and during the retrace time the (beam) current had to be switched off, otherwise the return of the beam could have appeared on screen too.  For the retrace periods blocking oscillators were ideal due to their very sharp (steep) pulse output waveforms which came from the strong positive feedback within such oscillator circuit. Of course these oscillators received syncronizing pulses from the broadcast video signal to exactly 'know' when to 'block' i.e. blank the beam current (via additional circuits), making it invisible on the screen.

Gyula

[Vortex1]

Hi Brad,

Just for the shake of correct technical info, the name 'blocking' oscillator was created in the era when sweep circuits were developed for television receivers. 'Blocking' was meant to cut the plate current off by applying a sudden high negative bias voltage on the grid of an electric valve.
In television receivers there have been a horizontal and a vertical oscillator to insure that the position control of electron beam (thinking of cathode ray tubes) should be from left to right and from up to down and during the retrace time the (beam) current had to be switched off, otherwise the return of the beam could have appeared on screen too.  For the retrace periods blocking oscillators were ideal due to their very sharp (steep) pulse output waveforms which came from the strong positive feedback within such oscillator circuit. Of course these oscillators received syncronizing pulses from the broadcast video signal to exactly 'know' when to 'block' i.e. blank the beam current (via additional circuits), making it invisible on the screen.

Gyula

Gyula

You have given a very nice explanation of the blocking oscillator. I can see from your writing style that you are an experienced electronics person, you speak the language accurately and concisely.

I built my first such oscillator back in the mid 1950's using a vacuum tube, and then later a transistor. I used it to illuminate a four foot fluorescent tube as a Halloween prank, like a Star Wars light saber. It certainly got a lot of attention on the streets that night, but not a lot of candy as folks were afraid of it, and I was ushered out of one home.
Since then I was always interested in those circuits, and studied the patents of TV's   Tektronix scopes and other devices that used such circuits. I also built many that are now still being produced in products for the company I was retired from as Chief Engineer.

It is always interesting to see old circuit ideas wrapped in a new name (Joule Thief, Slayer Exciter, etc.) Most of them are rather crudely thrown together without attention to the critical parameters that make for high efficiency, definitely not "engineered".

[MileHigh]

You two guys really know your stuff, I figured that out almost right away.  I never really knew what "blocking oscillator" referred to and never looked it up.  So I was always puzzled about that one.

I can throw in some early TV trivia myself.  I am not sure if it was for NTSC or an earlier version, but let's pretend the following example is for NTSC.  How did they decide on (262.5 x 2) = 525 horizontal lines?

I read that the early TV signal generators inside the big bulky cameras and similar equipment counted to 525 by cascading a series of simple tube-based counters.  So 525 is equal to 5 x 5 x 4 x 3 etc, etc.  So just the simple act of counting in the old days was a challenge and required some cascaded tube counter circuits.  In other words, they were "slaved" to pick 525 lines as dictated by a need to find a line counter system/circuit that was realizable and didn't consume too much power and was quite dumb and inflexible when you think about it.

If you look it up on Wikipedia a Joule Thief's operating frequency is dependent on several parameters, including supply voltage.  However, I am pretty sure the core timing mechanism is based on a variation of an L/R time constant, and not on an RC time constant.  The design is based around a main power coil and a feedback coil, after all.  Capacitance has almost nothing to do with it.

I find the schematic of the electo-mechanical flasher to be somewhat cryptic but I think I recognize the core operating principle at play, and it has nothing to do with any kind of electrical RC time constant.  Rather, it's based on the good old mechanical house thermostat that has a strip of two dissimilar metals that bends with temperature change because of the different coefficients of expansion of the two metals.  As a kid, I remember dismantling the standard Christmas tree light flasher and saw the same metal strip.  When the Christmas tree lights were off, a small current was still flowing to heat up the metal strip.  Then when the lights were on, no current was flowing through the heating resistor and the metal strip started to cool.  I am pretty sure the mechanical flasher schematic shown is based on that principle.  So it's based on a thermal RC time constant, not on an electrical RC time constant.

It's helps to dismantle things when you are a child to try to figure out what makes them tick!

[Vortex1]

There is plenty written on the theory operation of the blocking oscillator on the net, and also in those dreaded textbooks of old. It is also interesting to see this venerable and long used circuit getting rediscovered by a host of new "inventors" that like to rebrand old iinventions in their own names. That is ubiquitous.

Those wishing to understand the three possible  switching modes  and operation of this classic circuit should read the wikipedia entry or go here:

http://mysite.du.edu/~etuttle/electron/elect37.htm

By the way it goes back much further than 1969, possibly to the Major Armstrong days.

Milehigh, you are 100% correct, the flasher as used in auto turn signal circuits of yesteryear is an electro thermo mechanical switching device (to be precise) that has nothing to do with an Resistor Capacitor time constant.
Anyone claiming it does exposes the depths of their ignorance. Of course they will argue otherwise by some stretches and pretzel logic.

[EMJunkie]

Changing the shown Capacitor gives a different frequency: R X C = T, either way this is a Time Constant and it is associated with the Electromechanical Flasher.

Where:

R = Xc, Xl and Resistive components. (Impedance)
C = Capacitance in Farads.
T = One Time Constant.

   Chris Sykes
       hyiq.org

P.S: The Topic was not about the Thermal Flasher.