Need to trigger 4 relays for a single pulse

[anbudanarunm]

Hai, I am new to this forum. I am in a need to design a circuit which need to trigger 4 relays for a single pulse. My trigger pulse will come from the IC 74LS318. Basically it's an 3 to 8 line decoder. can any help me to solve this?

 

[brunofunchas]

HEllo,

Try to use a flip-flop SR and with transistors on the output to drive the relays.

Regards,
Bruno

 

[anbudanarunm]

could please provide the basic circuit diagram for this if possible

 

[hameeds01]

hey if u want to use 3 to 8 decoder then u need 3 inputs , use D-flip flop on the output of each decoder line & a driver to trigger the relay thatz it

 

[anbudanarunm]

I have one more doubt. Shall i use the ULN2803 which is a relay driver at the outputs of D flip flop(74LS138) and connect 4 relays/ULN2803 output directly.

 

[hameeds01]

yes u can use ULN2803 (max = 500mA) as a Relay driver. hey don't 4get to connect pin#10 of ULN2803 with +ve supply
another option is u can use a simple cheap transistor(as a switch) + diode as a relay driver

don't 4get to press helped me button

 

[anbudanarunm]

Thanks for the immediate response.