Short press of a button - timed, long press - off when released

Hi all,

I have electric curtains on my windows which are regulated by a simple DOWN-OFF-UP button. Current function of this switch is that as long as it is pressed the curtains fall or raise and when they reach end position the motor is switched off automaticaly. What I have designed so far is simple 555 timer schematic which when activated by a short press will provide contact for a relay which will be on for about 30-40 seconds which will fully open/close my curtains.

The problem is that sometimes I want the curtains half way or so open. I want when I single press and release the button shortly to have the timer activated, but if I hold for more than say -1-2 seconds this timer to be invalidated and manual release of the button to stop the opening/closing of the curtains.

Can you help me how should I modify the schematic?

kdobrev said:

What I have designed so far is simple 555 timer schematic which will provide when activated by a short press contact for a relay which will be on for about 30-40 seconds which will fully open/close my curtains.

Click to expand...

I think the old working system is using limit switches to let motor know the the curtains reached up/down to stop the motor.
In your design, using timer may cause the motor to work/stop in unwanted areas, before or after the required limits.

kdobrev said:

The problem is that sometimes I want the curtains half way or so open. I want when I single press and release the button shortly to have the timer activated, but if I hold for more than say -1-2 seconds this timer to be invalidated and manual release of the button to stop the opening/closing of the curtains.

Click to expand...

In my opinion, this would be much easier using Microcontroller, and yes for this purpose you may use timer.

In your design, using timer may cause the motor to work/stop in unwanted areas, before or after the required limits.

Click to expand...

I think these limit switches are mounted on the curtain itself so they cut off the motor no matter my relay/button has closed the circuit or not. Currently when an end position is reached no current is supplied to the motor even with button pressed.

Can you point me how should I use such a microcontroller/timer. I'm still new to this and a link with something similar will be of a great help.

Better schematic with junction points

Presumably the op doesnt have facilities for programming microcontrollers.

I'd be inclined to connect the p/b to the 555's trigger input and also via a cap to the reset input.

So then one press over 1/4 sec or so starts the timer and closes the curtains (reset pulse is shorter than the trigger pulse thanks to the cap), and a short blip press resets the timer and stops the curtains where they are.

I've never tried this so I dunno whether its viable or not.

Althought I did not quite understand you, I tried several ways and nothing produces the desired result. Another idea of the functions is to start the timer with the button and stop it if pressed again.

I was also thninking of combining two 555 times - one connected as toggle switch https://todbot.com/blog/2010/01/02/momentary-button-as-onoff-toggle-using-555/comment-page-2/ and the second one would be my schematic but this again leaves a gap of stopping already running timer.

Any furder help would be appreciated.

Maybe a simple ON-OFF-ON switch would do the job if there is limit switches mounted on the curtain.

This to replace your "DOWN-OFF-UP button" witch is I suppose a MOMENTARY ON-OFF-MOMENTARY ON switch.

**broken link removed**


Alain

This should do what you want