At first thanks to all who gave me tips and informations until now. I will specify the function of the IC I try to identify a bit further: The whole assembly seems (as far I had the possibility to measure) only to produce a clipped, rather distorted 40 kHz signal which is frequency modulated with an audio signal (whatever you like, music, etc.) fed in through a connector. The modulated 40 kHz output goes to a pair of ultrasonic piezo transducers. Currently I have only a handmade scetch, but I could provide a CAD schematic. I will not post in on my homepage, but I could e-mail it on request. Besides, I checked all ICs with 7501 or 8025 (the numbers on the chip I mentioned yesterday) as part of their name, and none fits. I tried Internet search engines, www.questlink.com, www.chipdir.com, searched in my old IC Master etc. Thanx, regards Matthias Mansfeld ----------------------------------------------- Matthias Mansfeld Elektronik * Printed Circuit Board Design and Assembly Am Langhoelzl 11, D-85540 Haar, GERMANY Phone: +49-89-4620 0937, Fax: +49-89-4620 0938 E-Mail: [log in to unmask] Internet: http://www.mansfeld-elektronik.de ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################