hi:

i have to design a undercarriage for a model hand launched glider for a competition.

the undercarriage must deploy AFTER 2 seconds, and the glider must remain airborn for at least 5.

heres the problem: it CANT use radio control.

so obviously a timer is the way to go.

i have the mechanical system designed, it just needs a timed actuator to pull the pin. once the pin is released the (torsion) spring loaded frame will deploy.

so i need a timed servo/rotary dc motor to activate after 2 seconds.

HOW CAN I DO THIS?

i have one real life 555 circuit built, and a simulated one in MULTISIM, but the output off the relay is showing decay on oscilloscope. it should be showing a square wave of a specified pulse witdth. it ISNT.

does anyone know ANYTHING about this kind of thing who can help me? i have spent many hours on google, and all the circuits seem to fail when simulated.

what i need a is a 5v-12v DC "monostable one-shot" circuit, that starts timing after i press a button, and either keeps the relay open for short/long enough to move my motor OR sends a correctly modified pulse (1.5ms) to my servo.

any ideas?

 

A simple 555 monostable will do the timing, but you need to figure out the mechanics from an electrical signal, also how you want to start the timing circuit.