DIY KNX choke/filter

[Leopard]

Automatic translation:
Ich musste KNX-Strom kaufen, aber es war zu teuer, also habe ich normale 18-V-Laborstrom getestet und danach nur 560-uH-Spulen hinzugefügt. und es funktionierte einwandfrei und versorgte das KNX-Netzwerk.

nur 2 einfache Spulen.


eng:

I had to buy KNX power, but it was too expensive so I tested normal 18V lab power and I just added 560uH coils after that. and it worked just fine and and powered KNX-network.

not sure how good signal I got, I dont have scope at home... but next week im going to do some extra tests

just 2 basic coils (see the circle
photo5823192397826341129.jpg

[meti]

I guess that lab power supply is much more expensive than a Knx power supply (I did buy ones for 25€ for my test setup).

Anyway, shouldn't you use 29 V ?

[concept]

and what‘s the question or what we should learn from from this post?

[bazhuyu]

https://selfbus.org/wiki/devices/system-devices/43-electronic-choke

[Leopard]

I guess that lab power supply is much more expensive than a Knx power supply (I did buy ones for 25€ for my test setup).

Anyway, shouldn't you use 29 V ?

yeah, it should be 21-30

and what‘s the question or what we should learn from from this post?

I was just super surprised that it actually worked, I was bored and didn't know what to do as I lost my test KNX power

https://selfbus.org/wiki/devices/system-devices/43-electronic-choke

ok, now I don't understand, if I look https://www.knx.org/wAssets/docs/dow...-Basics_en.pdf (figure 6), I got an idea that '0 V' isn't grounded and signal can be seen on that one too (ofc. inverted if compared to 30V line)

But your link doesn't seem to work like that

edit: ah, I found the webpagewhere is mention that its non symmetrical on purpose because some oscillating, thanks for the link.

[concept]

none of these hobbyist suggestions meet the knx specification and they should not be used in a serous installation.

[meti]

They may not be certified, but that doesn't say anything about meeting specifications, does it?
It's the DIY forum - that's exactly what I would expect here 🤷

[concept]

gadgetry‘s like the thread opener described (simple choke without output protection) have the potential to damage the knx components.

[Leopard]

gadgetry‘s like the thread opener described (simple choke without output protection) have the potential to damage the knx components.

There is always possibility to break something. But in this case, power is limited to 20-30mA, just in case of short circuting something. (And I had no idea how it reacts just with coils as an filter, so better to have some current limits.) thats why lab power, even that was bit low voltage.

Edit 6.6.2022
just with coul, there was bad resonanse in signal, but adding 56ohm resistors paralel with coils made signal clean.

at the end, I had 790uH coils and 56ohm resistors paralel, and I got somewhat nice signal. but need to do extra tests.