Audio Modulated CRT Flyback Transformer Loud Sparks

[hashtala]

Hello,

I have built driver for CRT Flyback transformer with audio modulation. I have measured input signals and everything seems to be fine. When I inject audio and gap is large enough that it cannot spark, I can clearly hear the modulation. However, when gaps get short enough that it can spark, I get very thin (but long) purple sparks that are very loud, so much so that I cannot hear audio modulation anymore.

What could be the issue?

Voltage - 14V current drawn 12-13A RMS

How can I make brighter silent sparks?

Thanks

[davekni]

Hard to tell without more details (circuit diagram, scope waveforms if available, pictures of setup).

One possibility is that your flyback transformer has an internal filter capacitor on HV output.  That cap will charge and then spark.  The cap discharge makes loud sparks.  You could try adding a high-voltage power resistor in series, but it will in-general be difficult.  AC-output transformers are likely to work better, though are hard to find.  A DC-output one without output capacitor might be OK.  I haven't personally tried to build such a project as yours.

[hashtala]

You have a very good point, it really sounds like a big capacitor discharging.

it has two knobs, screen and focus, can I get away by dialing them ?

The transformer is TV 29-FS4RL if it helps.

I do not have scope pictures but I have measured them and it looks fine, I am getting about 5ns edges

[John123]

Voltage - 14V current drawn 12-13A RMS

How long are your sparks when measured with a ruler and can you post a schematic? Those power levels sound rather high, is the switching device heating much?