hi guys,
I have to drive a mechanical relay from an edge Triggered D-flip flop. output voltage from the flip flop at max when using IC 4013 is 17.27 volts at 40.6 mA. My relay coil rating is 24 volts, although i can drive it using 16 volts because minimum driving voltage is 70% of the max rated coil voltage. i have tried transistor 2N5296 but i am not able to bias it properly i guess. so basically i'm stuck. Any suggestions. thanks
hi guys,
I have to drive a mechanical relay from an edge Triggered D-flip flop. output voltage from the flip flop at max when using IC 4013 is 17.27 volts at 40.6 mA. My relay coil rating is 24 volts, although i can drive it using 16 volts because minimum driving voltage is 70% of the max rated coil voltage. i have tried transistor 2N5296 but i am not able to bias it properly i guess. so basically i'm stuck. Any suggestions. thanks
Hey,
its a positive edge trigger D- flip flop, instead of a clock i'm using a momentary push button.Basically to power up the IC i am using a Battery eliminator which can regulate from 1.5 volts to 12 volts at 500 mA. By applying a max of 12 volts from the the eliminator i'm getting 17.27 volts at 40.6 mA at Q output of the flip-flop.
The coil rating is around 55 mA
hi,
The max recommended voltage for a CD4013 is 15V at which it can source or sink approx 6mA.
The gain of a 2N5296 at 100mA is approx 30.
So for a relay coil that requires 50mA at 24V the 2N5296 will be OK.
So I would suggest a transistor base resistor of approx 15V/.005 = 3.0K , say 2.7K
Connect the output of the 4013 to the 2k7 and the other end of the 2k7 to the base of the 2N5296.
Connect the emitter of the transistor to 0V and the collector to one end of the relay coil.
Connect a diode across the relay coil, to protect the transistor, cathode of the diode to +24v and the anode to the transistor collector.
Yes, it's not surprising you needed to reduce the base resistor. Eric probably didn't notice that the gain of 30 was specified with a collector-emitter voltage of 4V so the voltage drop was probably too high.
Yes, it's not surprising you needed to reduce the base resistor. Eric probably didn't notice that the gain of 30 was specified with a collector-emitter voltage of 4V so the voltage drop was probably too high.