I wonder how I can make a recording of a little gig with simple equipment, just for listening back. No professional sound needed.
Can I use a normal tapedeck and record the signal with two mikes after the sound check. Is it possible to get a reasonable recording this way ?

If the PA/board has an RCA line out and you have a tape deck with an aux in, you're all set. Of course, depending on how much of the equipment you mic, you're sound will vary. Regardles, you can get some fairly good sounding board tapes this way.

Only the voices run over a PA.
The rest of the instruments use their own amplifier, the drums are mot miked. It's not possible to do this with the coming gig. I wondered if i still could get a recording just for listening back, as feedback to the band.

We record a gig in a little cafe, A normal tapedeck and two microphones on stands before the stage. It sounds fairly reasonable. It';s very good for listening back and rehearsel purpose.
I was amazed by the quality of the recording. With minimal equipment and effort a good result.

The last two times my band played our we had someone film us with a camcorder- it actually picked up some really good audio. Some of it should be up on the web soon. Stay tuned.

If it is only for the one gig which you are not miking instruments, I'd say use two condensers halfway across the room you're playing in. You'll get some crowd noise, but if your instruments are cutting through like they should you will hear them just fine. Also, if it is for the band only, try miking everything at a practice session and record using the RCA's on your board. This way you can hear and correct your mistakes before your actual show.