I'm working on a circuit for a hobby project (not homework). In this circuit is an IC that carries out the functions of being a countdown timer and driving a seven segment LED display. I want to be able to do either of the two following things: 1. Have the logic level of one of the pins on the aforementioned IC determine whether a load is driven or not driven. 2. Drive one of the pins on the IC high or low depending on the the logic level of some signal. For number 1, as an example, there is a pin on the timing chip that is always at logic low whenever the value of the counter is 00:00 (and logic high otherwise). I want to use this "zero" pin to cause a load to be driven whenever it is low. I don't want to use a BJT, because I don't think that the pins on this IC can source or sink very much current at all, and I don't want to have to worry about having sufficient base current to make the transistor work. A MOSFET would be perfect, but I don't think there are discrete, low-level MOSFETs, and a power MOSFET would be overkill (when I say a "load", I'm talking about an LED powered by 5 V. I'm not talking about switching huge currents here). I thought maybe I could use a logic buffer/driver chips like a 7406 or 7407 (depending on the specific case). However, it doesn't seem to be quite what I need. Instead of a truth table like: input --> output ------------------ high --> high low --> low What I really want is: input --> output ------------------ high --> high impedance low --> conducting For number 2, it's the same idea, except that I would connect the pin on the timing IC to the *output* of my driver/buffer/whatever, instead of having it be the input. Can you recommend something that will do the job?