Here are the schematics to a DTMF decoder: -==- C1 .01uf cap S2 momentary, normally open C2 47uf cap S3 momentary, normally closed C3,C4 .1uf cap IC1 SSI202 DTMF decoder R1,R3 4.7K res IC2 5101 256x4 SRAM R2 1M res IC3 CD4070, quad XOR R4 1K res IC4 74C93, ripple counter LED 7segment common cathode IC5 74C48, BCD to 7-segment X1 3.579 Mhz colorburst, HC case IC6 78L05, 5v regulator S1,S4 SPST switch -==- +5v +5v +5v __|_ _______| _|_ _|||__|_ | _____|____ _____|___|___ | 345 16 | ____ |_|2 5 1|___________|9 17 22 10|_______|7 13|_a| | |_|3 18|___________|11 12|_______|1 12|_b| L | |_|8 S 17|___________|13 14|_______|2 11|_c| | | S 16|___________|15 5 16|_______|6 10|_d| E | | I | | 1 | | 9|_e| | C1 | 2 | o__+5v | 0 | | 15|_f| D | o__||__|9 0 4|__o _|1 1 | | 14|_g|____| || | 2 7|__o |_|2 S | |___8____| | o _|14 10|__| |_|3 R | | \ | | | 15|__| |_|21 A | GND /R4 GND | |_11_____12| GND |_|18 M | \ | | R2 | |_|19 | | | |--/\/--| |_|8 | ^ o | | _ | | |__20___4567__| \ S4 | |_|| ||_| | | |||| o | ||_|| GND | ||||___________ | | X1 ___| |||__________ | GND | +5v | ||_________ | | | _____| | +5v |_________ | | | | __|_____|_____ | _|_________ || | | | | 13 14 | | | 4 | || | | | | | _ | | | 12|_|| | | |___|12_>)_)-----11|____| | 7 10|__| | | |_|6__ _ | | 4 9|____| | _|5__>)_)------4|_________|14 C 13|______| +5v |_|3_______ | | 9 8|_| |______|2__ _ | 9|___ | 3 | \ ___|1__>)_)-- 8|___| | | R1/ | |___________7__| | |_1_2____11_| \ | | | | | | S2 o__|__| | | | | | ^ _|_ | | +5v | | | \ ___C2 | | | | | | o__|__________________|______| / | | | | \R3 | | | GND /____|_| | |________o<--o S3 | GND -==- (optional) ^ +5v / _____ _|_ ____o o__|78L05|____o+5v _|_ _|_ | |_____| C3 ___ ___ C4 9v | |___| | GND | (-) GND For instructions and details write to: HB Technologies PO Box 2771 Spring Valley CA 91979 enjoy--- Dispater . . . ^ `____ + ________ __ ____ _|\ _ _ ______ __ _|\ ___ \ \ /.(__ __). | # /. // | \ \| (__ __)_ \/ | \/ / |\/: \/ | |/ \/ | | / |_// | \ : \/ \ _/ / | \ / + | | \ _ \\ / _ \ / | _\ : / . /\ / \ \ : /'---. |_____/_| /_\/\__| / \___ |_\___/__| /._\/__/\ \___/____/ |/ |/ \| |/ \__/NomaD93' : v . : ~ . ' < Advertisment added using -=Bad Ad=- 1.91 by Troed/Sync. BBS: +46-451-91002 >