Dangerous Posting?? "Common Mode DC Power Filter"

[R.G.]

The post titled "Common Mode DC Power Filter" contains nothing other than a link which purports to be a link to something that might or might not be a youtube video.
The poster is a new member, and this is their first post.

While it may be perfectly innocent, it fairly screams "CLICK ON ME TO GET MALWARE DOWNLOADED ONTO YOUR MACHINE!!! HURRY!! CLICK ON ME!!"

I have pretty good shields and protection setups on my machines, but I would not click on it except possibly on one of my burner machines which I can flush entirely.

[Colossal]

I saw that. The link actually does lead to a video about a power supply. No schematic and nothing really useful. I'm more than happy to delete the user and block his IP.

[R.G.]

If it's innocent, that's probably not necessary. I just have a low threshold on things like this. Maybe just a pm to the user to explain what they're posting.

You're braver about possible malware links than I am. I just wimped out, was too lazy to get out a burner machine.

Thanks for checking.

Edit: I forgot to mention the subtler thing I was thinking of. A man-in-the-middle attack gives you a link. You click the link, an evil website installs the malware, then fetches the purported results from the real web site and feeds it to your browser. Nasty and hard to detect.

[gmm20]

No, I don't normally post schematics, to ensure my design work does not fall into the wrong hands, like MerlinB.
You want to throw me off, go ahead....
It's a real circuit, when I was thinking of a more painless way to provide a clean power source for something like filament power for a 300b.

-g

[R.G.]

No, I don't normally post schematics, to ensure my design work does not fall into the wrong hands, like MerlinB.
You want to throw me off, go ahead....
It's a real circuit, when I was thinking of a more painless way to provide a clean power source for something like filament power for a 300b.

You don't need to get defensive. This was not an attack on you. Instead, I think that it was reasonable caution in an era when a significant fraction of the internet is malicious.

Read my comments about your post. It has a large number of characteristics of an abusive posting. I moderate another forum, and I see lots of real attempts to post malicious links. Here's a recap of the issues:
> Your posting contained nothing but a a title and a shortened link. (Although I see that you've edited it since it was first posted with only a URL)
> The shortened link made it impractical to do anything but click on it or not.
> Fake links and man-in-the-middle attacks are rampant on the web.
> It was your first and only post to the forum. You have no history on the forum of either contributing or genuinely asking questions.

There are a number of things that you could have done to make the post less of an alarm flag.
> Participate in the forum for a while first before posting URL-only links. This gives you at least the trappings of a real, non-malicious actor.
> Provide some discussion of what the link is about and why the content is a good, bad, or not-understood technique or approach.
> Provide a non-shortened link, not a blind and shortened link. This lets the possibly suspicious reader type in the link themselves without clicking on an unknown link.

I still have some issues. Your response above seems reasonable at first glance, then gets odder and odder on re-reading. I've played with some of the AI chatbot things, and they make it easy to generate realistic sounding things that don't quite add up. Here are my thoughts on this reply.

No, I don't normally post schematics, to ensure my design work does not fall into the wrong hands, like MerlinB.

I don't normally post schematics either. But I have, on occasion done so over a period of some years.
As to keeping my schematics from falling into the wrong hands; I don't think that a power supply schematic in the wrong hands would be a disaster. There is remarkably little technology about power supplies that hasn't already been put into practice long ago. If you mean by "wrong hands" that someone would copy or "steal" your work - sure, we're all proud of what we thought of, but even then if you're not writing a book or selling amps based on the circuit, it's not like there are evil villans out to conquer the world with tube amp circuits. And is Merlin really such a threat? Merlin writes a lot about well-known circuits, re-threading them into new books. Further, I would challenge you to come up with a circuit technique with tubes that was NOT in use before, say, 2000.

You want to throw me off, go ahead....

I suggested that this was not necessary.

It's a real circuit, when I was thinking of a more painless way to provide a clean power source for something like filament power for a 300b.

This, plus the "wrong hands" thing above is what makes me wonder if an AI chat program wrote this post. AI chatbots generate completely plausible text. But there is not necessarily any fact behind what they write. Here are some oddities I noticed.
> There is not just one single DC common mode choke video on youtube. I counted a dozen before I decide that there are "many". Some include schematics, some don't.
> 300Bs are not (in my reading about them) super-sensitive to noise on the heater winding, even though sure, it's possible that common mode noise could be an issue if it was low enough impedance to be piped into the cathode. 300B and most other power tubes have the cathode as a low impedance node, which would be difficult for a noise source to drive. It's probably more practical to work on making the heater current source be quiet.
> I've worked with common mode chokes in power supplies professionally. They do impede noise currents from both wires that pass through them relative to some other "ground". It's not clear what this other "ground" you're implying with "common mode choke" use. If it's signal ground, OK. If it's electrical network ground, there may be even simpler ways to do it.
> You gave no hint of what the circuit looks like, or what you are blocking, attenuating, or impeding with the choke. You would have gone a long way toward plausibility by providing a context, but there was none.

As I said to colossal, it's probably innocent.

[gmm20]

I should not mention the 300b does not have a cathode.
Well , for example, some guitar amp builds do use dc filaments, like the Valve Junior.
But one of my design goals, is to use this circuit to obsolete other power supply filters, like switching regulators, and linear regulators.
Efficiency goes up, as when you use the common mode rejection, asvery little waste heat is generated.

More parts expected to arrive from my vendor, this Friday. Then, I should be able to demonstrate full-range-of-output-voltage.


-g

[pompeiisneaks]

I should not mention the 300b does not have a cathode.
Well , for example, some guitar amp builds do use dc filaments, like the Valve Junior.
But one of my design goals, is to use this circuit to obsolete other power supply filters, like switching regulators, and linear regulators.
Efficiency goes up, as when you use the common mode rejection, asvery little waste heat is generated.

More parts expected to arrive from my vendor, this Friday. Then, I should be able to demonstrate full-range-of-output-voltage.


-g

Your other thread as well as your replies to this one seems heavy on the vague and light on the actual useful content. Also you've been hinting at what appears only to be HiFi designs (300b and mentioning in the other thread you didn't do guitar amps anymore post pandemic) so why specifically do you feel the need to vague-post on a forum dedicated to guitar amplifiers?

If you're willing to share actual information, and real value, we welcome you, as has been mentioned. If you're going to continue the less than useful vapid nonsense, I'll be happy to ban your account so we can keep the forums 'on task'

~Phil

[sluckey]

If you're going to continue the less than useful vapid nonsense, I'll be happy to ban your account so we can keep the forums 'on task'

Please, just do it. Why wait any longer. Just gonna get worse.

[Colossal]

Done. Gary won't be down for breakfast and thread is locked.