Remote Control by Mobile Phone

Switch & control using DTMF signaling

Published in issue 348, November 2005

Resistors:

R1 = 390k

R2 = 1k

R3,R5,R12,R15,R17-R23 = 10k

R4 = 100k

R6-R10 = 33k

R11 = 470k

R13 = 220k

R14 = 47k

R16 =2k2

P1 = 1M preset H

P2 = 25k preset H

Capacitors:

C1,C3,C6,C7,C15,C17-C20 = 100nF

C2,C13 = 1µF 16V radial

C4,C5 = 27pF

C8 = 2µF2 16V radial

C9,C10 = 220nF

C11,C14 = 22µF 16V radial

C12,C16 = 10µF 16V radial

C21 = 1nF

Semiconductors:

D1,D2 = 1N4001

T1,T2 = BC547B

IC1 = MT8870BE

IC2 = PIC16F84A-20/P (programmed, Publishers’ order code 040415-41*)

IC3 = ISD25120P (Winbond, Digikey # ISD25120P-ND)

IC4 = 7805CP

Miscellaneous:

K1 = 4-way SIL pinheader

LS1 = 16 Ohm miniature loudspeaker

MIC1 = electret microphone capsule

S1,S2  = pushbutton, 1 make contact

S3-S7 = on/off switch, 1 make contact

X1 = 3.579MHz quartz crystal

Mobile phone with headset (see text)

PCB, Publishers’ order code 040415-1*

PIC source and hex code files, Publishers’ code 040415-11