plz help me with 5- pin relay jqc-3fc-t73 .
i m so confused about the connections .. i hv 12 v source .. and i want to glow an LED .i am also using uln2003 .. plz cn ny1 tell me the connections ...??
AS albert stated, you can drive the led with ULN2003.
Can also drive with relay,
Connect 12V to ur one end of your relay coil and another end to ground. Normally C(Common) and NC(Normally closed) are connected. When you apply power to coil, C(Common) and NO(Normally Open) gets contacted. connect a suitable value of resistor to NC terminal of relay. and another end of resistor, connect the led anode and led cathode to ground.
plz help me with 5- pin relay jqc-3fc-t73 .
i m so confused about the connections .. i hv 12 v source .. and i want to glow an LED .i am also using uln2003 .. plz cn ny1 tell me the connections ...??
What you want is not very clear. Do you want to drive the LED with the relay? What LED is it? Is it a standard 3mm/5mm LED or a high power one? Why are you using a relay and not a transistor? Where does the relay drive signal come from? Will you be using ULN2003 or is it also okay if you drive the relay coil with a transistor?
Nothing special, just use low current LED (2mA) with adequate resistor 5,6K. Put led and resistor between +12V and each ULN2003 output in parallel with relay coil. One end of resistor is connected to 1C (output of ULN2003), other end is connected to LED cathode, and LED anode is connected to +12V.
This circuit is not good. There is much better projects based on this concept.
You dont have password for accessing to system, anyone can connect on your number and play with dtmf codes on keypad.
Also you dont have remote information over PSTN about actual state of relays.
Describe S1 relay-switch. Its not clever to drain lots of constant current from telephone lines. Calc 0,5mA-1mA max in On-Hook state, or you can have some bad trouble with your telecom company, if there is newer digital telephone exchange you can be even automaticly disconnected (banned) for longer time, all until some telecom worker investigate cause of that current draining and do some tests.
Look circuits in this EDABoard thread, specialy post #8, and how to simplify and decode DTMF just with single PIC and few discrete components. Access is secured with password (examples: #3479#31* - Turn ON channel 3, #3479#80* - Turn OFF channel 8, #3477# - Invalid password). There is two variants 1 channel with 12F629 or 12F675 and 8 channel with PIC16F628 :