This receiver built by Walter Krämbring uses an Auriel receiver card. Walter is somewhat more brutal regarding the connection to the microphone input than I am - he skips the capacitors altogether. Apparently the Auriel device can handle the DC level from the microphone.

The Circuit diagram is like this:

The receiver device used is made by Auriel an called RX-4M50RR30SF. It is available from many suppliers, but Walter recommends http://www.soselectronic.com, where the device costs 5.93 EUR.

Here is a closeup of the radio device with the hand winded coil in front of it:

Walter has built in an USB sound card together with the receiver, so the resulting device is a USB connected 433MHz receiver. He uses the power from the USB-interface to drive the circuit.