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saykodayi



Joined: 09 May 2006
Posts: 6
Post25 Feb 2007 16:04   need help
do you have any circuits about telephone ring detection,links or ideas? urgent help please



many thanks from now
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pakitos



Joined: 14 Nov 2005
Posts: 310
Helped: 38
Post07 Mar 2007 14:59   Re: need help
For a quick reply try this: (for cellular)
R1____________100K 1/4W Resistor
R2______________3K9 1/4W Resistor
R3______________1M 1/4W Resistor

C1,C2_________100nF 63V Polyester Capacitors
C3____________220µF 25V Electrolytic Capacitor

D1______________LED Red 10mm. Ultra-bright (see Notes)
D2___________1N5819 40V 1A Schottky-barrier Diode (see Notes)

Q1____________BC547 45V 100mA NPN Transistor

IC1____________7555 or TS555CN CMos Timer IC

L1_____________Sensor coil (see Notes)

B1_____________1.5V Battery (AA or AAA cell etc.)

the link is redcircuits.com

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Last edited by pakitos on 08 Mar 2007 11:07; edited 1 time in total
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rogerynt



Joined: 06 Mar 2007
Posts: 109
Helped: 11
Post08 Mar 2007 6:42   Re: need help
Works in most European countries

L5, L6 : for EMC suppression issue. Avoid unwant signal radiates through telephone line.
VAR1 : varistor, for protection against high voltage
Z1, Z2 : standard zener diode
PC1 : bidirection photocoupler. You can use PC817 or equivalent if kine reversal detection is not required.

Added after 13 minutes:

Can you read the schematic ?
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