These devices were very commonly used in audio tone decoder systems, specifically land and radio based communications systems.
The device provides excellent stability of selected audio frequencies (usually in the audio range) with high "out of range" signal rejection.
These are new old stock spares that we kept on hand for special radio communications systems that used DTMF (Dual Tone Multi Frequency) signalling, each NE567 is set to decode one tone, 2x NE567's being used for each DTMF tone set. Usually dual tones provided a high degree of rejection for "non valid" tone signals. Consumer telephone equipment used a particular set of tones, telephone exchange trunk equipment (NEC for example) used their own special control DTMF tone groups and specialised radio communications systems used yet another set of user determined tone groups - these devices are extremely flexible in use as you can set your own customised tone groups that no-one else can easily duplicate.
Philips
Part number: NE567N
Function: Tone/Frequency Decoder
Wide useable frequency range: 0.01Hz to 500kHz
High stability
High out of band and spurious signal rejection
Output capable of 100mA sink
8 pin DIL plastic package
Datasheets and application information is readily available online or I can provide one (if requested)
New unused, old stock and stored in the suitable, safe packaging material.
