Its very rare to hear about DK1 in a development context these days. Oculus said that the DK2 would work for at least the rest of 2016, but even that will probably get dropped eventually.
I fear you may have to use very old versions of runtimes, drivers & Unity to get support for the DK1 these days. I think its a dead end.
I know thats the problem but I could still work with that.
Its just for 3D visualization and walktrough stuff.
I had it running one and a half years ago but I dont remember which versions I used.
Well if you canāt find your way back via the purely oculus method and old versions of everything, it sounds like earlier this year some people were having success in some games via a different method. Use the Oculus 0.8 runtime but also install SteamVR and then use oculus via OpenVR instead of the oculusās own sdk & apps. You might even be able to use latest versions of Unity via that route, but I cannot tell because I donāt have suitable hardware to test. Just keep in mind that newer versions of unity give you explicit control over what VR APIās are used in your project, and if you try this suggestion you probably want to have OpenVR at the top of that list and remove the oculus rift item.
I wonāt post links to random websites I found detailing the non-Unity part of this, but just googling for something like āDK1 0.8 SteamVRā will probably yield fruit.
Iām on a Mac, but have been using Unity 5.3.5 (and now 5.4.1) successfully with a DK1. Iāve fixed my Oculus runtime at 0.5.0.1. No plugins, Iāve enabled āVirtual Reality Supportedā in Player Settings, and it works with Play in the editor or as standalone. I donāt mirror my display, the DK1 is a separate āmonitorā.
PS: Actually Unity 5.3.5 worked perfectly for my DK1, but after upgrading to 5.4.1 last night the rendering appears all āwashed outā in my DK1. So maybe try Unity 5.3.5 first?