TALE OF THE IMPLODING TV

[duff]

Guys,

I don't know much about the internal workings of a TV but last night I had a dream which may or may not be of significance here.


In the dream, I had posted an experiment someone else had done and was reevaluating the results. I was being told that there was some significance related to the capacitance in the clamping circuit.

From Wikipedia:

Alternatively a clamping circuit may also be defined as a circuit which inserts a DC component into a signal. Perhaps the most common such clamping circuit is the DC restorer circuit in analog television receiver, which uses reference levels in the sync pulse in the horizontal blank (inserted during video modulation).

The network must have a capacitor, a diode and a resistive element, but it can also employ an independent DC supply to introduce an additional shift. The magnitude of R and C must be chosen so that t = RC is large enough to ensure that the voltage across the capacitor does not discharge significantly during the diode's "Unconducting" interval.

[HEYDUDE]

Very significant post, Duff. Your dream has a great deal of meaning, at least to me. A while back I was experimenting with DC restorer circuits to auto-bias the pulses above zero so that they do not reverse.

The non-reversal of the signal (below zero) has been alluded to as a key necessity by Spherics. This prompted me to use the pulse itself to provide the bias with the DC restorer circuit rather than externally.

I believe a few others may also have tried this.

Keep dreaming, you are tuning in to something.

[Grumpy]

deleted

[giantkiller]

These effects in this pic were caused by a 556 chip failure.

When the pulse was on things were under control. When off the ground had noise. But that doesn't explain the 3.5x voltage height. False or uncontrolled fet triggering? I am still impressed with what I see there.

Imagine a 17kv transformer in this mix.

--giantkiller.

[Peterae]

Argh Ground noise is a wonderfull thing, i have spent months trying to get rid of it during TPU experiments with high Dv/dt switching, and i guess i finaly managed go get rid of it by using multi layer pcbs, after all who wants 300v of PK pulses across 1mm stretches of pcb track.

Modern EMC law is a great thing, use multiple layer pcbs and you spread the energy across gnd planes which have multiple capacitances to dissipate the RE Energy and loose the horrible ground noise or we can use ferrite to obsorb this energy to make sure we dont find it's true nature.
Hang on did i mention that ground noise is RE offcourse it is, Tesla was able to light light bulbs across a U shaped copper bar, thank god EMC kills this energy, we wouldnt want to discover free energy would we.

The great news is that we can pipe this RE oops ground noise to an iron wire delay line that is capacitively coupled to ground along it's length to sharpen the speed and amplitude of this pulse and if this delay line is not terminated relfect it back to where it was generated, but now we have our original hi Dv/dt pulse with a much sharper high eneergy reflection on top of it if delayed by the correct timming which is about 10% of the oringinal pulse time, trouble is the dam delay line keeps glowing blue sparks and melts.