12V sequencial on delay

[ut_]

Hi I need help with a simple delay circuit. I have a 12V signal, A, when A is on I want to have a delay of x-millisecond delay to output B and B would trigger C with x-ms...and etc. When A is off, all other signals are off. I figure if I can make one delay circuit I can just repeat for the rest.

TIA.

 

[andre_luis]

Could use an IC having 4 comparators in a cascaded arrangement ( output from previous as input for the next ), and at the reference input of each one a R-C net to perform the desired delay.

 

[D.A.(Tony)Stewart]

It depends on signal current and accuracy needed, otherwise many solutions.

Analog vs digital ,
low current vs high current ,
low side vs high side vs CMOS switch

 

[ut_]

The outputs will be powering some LEDs with 2.1Vf/70mA. I want to use only analog and been looking some transistors designs.

 

[FvM]

There are many kinds of analog circuits possible, e.g. with discrete BJT or MOS transistors, using comparator or timer ICs.

The question about intended timing accuracy is still pending.

 

[D.A.(Tony)Stewart]

Since all transistor switches invert, a primitive cascade solution with 1Q device does not cascade.

What else should it do? Variable delay? Variable frequency? Recycle? Rotate? Reverse directions? None of the above?

 

[eetech00]

Hi

you can use a CD4060B counter/oscillator...

eT

 

[chuckey]

The easiest way for a coarse delay circuit is to feed your A signal via a resistor into the input of a CMOS gate with a capacitor to ground. Go for a quad non inverting type such as a 4071. If you connect a diode across the resistor, cathode to the A signal, when the A goes to zero the output of the gate will rapidly return to zero also. The output of each gate can then feed current into the base of the LED driver transistor and drive the next delay section.
Frank

 

[crutschow]

A simple analog/digital solution is to use a CD4106 Hex Schmidt Trigger. Connect each output sequentially to the next input through a series R and C to ground to get the desired delay between stages. The CD4106 has a high input impedance so you can use up to 1 megohm resistors to minimize the capacitor size for a given delay. The gates have a Schmidt Trigger input so they switch cleanly at the switch point with no oscillation.