Complete novice here --

I need to make a TTL switch/relay DC circuit (no real load) that does the following:

-Ignores short 'turn on' pulses, or a series of short pulses
-Time delay on in response to a steady 'turn on' signal (DC on, I guess)
- Immediate off when the steady signal is removed

The device involved is a rotating turret. If the turret is clicked into and held at a particular position, a downstream switch should be turned 'ON' with a short delay. If the turret is spun (clicking through several positions), the switch should stay off until the turret reaches a desired position and is held there.

Voltages involved are TTL 5V or so, but could be higher if needed.

Any advice will be greatly appreciated

 

You could use a series resistor with a capacitor to ground to delay the operation of the circuit and ignore pulses. To get it to turn off immediately you could add a diode across the resistor (cathode towards signal source) to rapidly discharge the cap.

 

As crutschow said is a easy way.
If that still can't solve your problem, you can add two schmitt trigger of MC14584 after R and C.

MC14584 datasheet.
http://www.datasheetcatalog.org/datasheet/motorola/MC14584BCL.pdf

 

Here's an attempt to put suggestions down on paper. Comparator used for schmitt trigger & comp. Load is still an unknown to me.