I have not used the 567, but I have used the XR2211 with pretty good results. The math to compute the center frequency etc. is straightforward and the chip needs pretty minimal external components. steve -----Original Message----- From: James R Albers [mailto:n9cyl@JUNO.COM]=20 Sent: Sunday, July 15, 2001 7:15 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Any experience with tone decoder 567 ? Joan Ilari said: > The key point is what you say : "the voltage controlled oscillator > (VCO) signal gets into the high gain part of the circuit". I may be having less trouble with the VCO signal getting into the high gain part of the circuit because I have down converted to my 2500 Hz tone detect frequency. I start out with about 100 dB of gain at 60 kHz, and down convert to 2500 Hz using a bipolar transistor mixer with L.O. (Local Oscillator) injection at the emitter. Of course, there are all kinds of mixing products; but I filter out the 2500 Hz, and send that to the LM567. You (I think) are detecting 20 kHz, and stray effects are greater at that frequency than at 2500 Hz. I tend to think that the LM567 is not the best tone detector available, but it is cheap! Maybe someone else on the Piclist can suggest a better performing IC. Hope this helps. Jim Albers -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads