I am making another battery charging circuit and am using the Max712 IC. I am charging 10 cells at .4mAh. There is an output called fast charge which is low if the charger is fast charging and high if the charger is in trickle mode. Getting a flash of inspiration, I grabbed my Radio Shack electronic projects book and found a little 4011 nand circuit that with using 2 gates, will flash a led when the circuit is in trickle mode and go steady when the output is in fast charge. I am using a 21 volt transformer for the charger and need to reduce the input voltage down to 3-12 volts (probably 5 volts for easy part accessability) for the 4011. Instead of using a regulator in a to220 1 amp package, I would like to use the to92 100 ma version. Using 2 gates , 3 resistors, a capacitor, and a led, do you think the circuit would pull more than 100 ma? I have to order whichever one I need, so I am asking instead of breadboarding. Gut check answers are welcome.

 

Just llok up the supply current spec for the 4011. Then add the current through the resistors and LED. Then calculate the power diss in the TO-92 reg and see if it is OK. If it's less than about 0.4W, you should be OK.