need help with simple small circuit design

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wozzzzza

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I have the need for a circuit operating on 12VDC to do the following
every time powered up, will close relay contacts for 10 seconds, then open the relay contacts for about 10 seconds then keep the relay contacts closed again permanently while power is applied to the circuit.
anyone help me with a simple circuit that will do this? i've been out of electronics too long and cant think of a way.
 

what ever is the easiest circuit to build, timing doesn't have to be accurate.
all it is switching is a 12v/5v convertor powering a USB device.
 

A 3914 IC in dot mode can do the job.

Attach its input pin to a capacitor being charged slowly. It has ten output pins. They change state, one at a time, as the capacitor charges. Adjust values so it takes 22 seconds total.

Connect the relay coil only to the pins that yield your desired timing action. Skip the other pins. Tentatively the skipped pins will be 5-6-7-8.
 

something like this? would this work you reckon??
what is the output of this chip, I cant work it out, input is ok at 12v, is output only 1.5v? would I need a transistor to power the relay?
 

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