I want to drive a relay of 12v,60ma circuit with TTL of 5v
I can use bjt ? how can i connect and any suggestions or thoughts?
below is the circuit,
Use ULN2803A.
...but 100Hz? I'm not sure.
Provide more information.
An electro-mechanical relay is not going to operate at 100Hz... If you want to turn the relay on when the 100Hz signal is present, you can add a diode, capacitor, and a resistor to "filter" the square wave. Or even better you could add a "one shot" multivibrator to hold the signal high until it's no longer being triggered at 100Hz.
okay ,100 hz is not enough
or if we dont consider 100hz signal then how can we design ?
Your relay will be "chattering" trying to keep up. What is the relay supposed to do at that speed?
Paul
it is just assignment question,my friends used to learn things electronic stuff
manisrinivas:
it is just assignment question,my friends used to learn things electronic stuff
So we are doing your friend's homework!
Well, it is again, an "XY Problem", isn't it?
We are given just half the information needed. A cryptic box labelled "TTL" which is an obsolete logic system using logic levels of 0 to 2.5 V, not compatible with current CMOS devices, a mysterious and misspelt reference to a 100 Hz square wave without indication of what it is desired to do with it, and a "number 2" relay with an again misspelt rating of 12 V, 60 mA with no indication whether this is the coil operating voltage or contact rating. 
And still no primary indication of what might be the purpose or practical application.
It's a losing proposition to be sure, and so far simply a waste of time. 
manisrinivas:
I want to drive a relay of 12v,60ma circuit with TTL of 5v
Simple, use a TTL O/C gate and free-wheel diode.
It is a reed relay of course, only those can switch that fast....
However why TTL, its completely obsolete and has been for decades.