1. Home
  2. Electronics Design
  3. Schematics For Delayed ON/OFF Switch??

Schematics For Delayed ON/OFF Switch??

I'd like to build up a switch that works identically to the switch on my Nokia 6010 cell phone, which is basically a membrane type button, which must be depressed for about 2-3 seconds or so, before the device is either turned ON or OFF.

I have seen schematics that use PIC chips with delays, in conjunction with N-MOS and P-MOS FETS, supposedly with low RdsOn, so that battery efficiency is still good, and with decent leakage while the device is OFF, in the tens of uAmps.

But I'm hoping someone out there has other ideas for ultra-low voltage drops, and ultra-low leakage current while the device is off, obviously to extend battery life, but with the delayed reaction so that accidental switching is minimized.

Thanks in advance.....

Reply to
Paul
Loading thread data ...

When it is off and the button is not pressed, it doesn't need to take any power at all. Basically the idea is like this:

semiconductor Switch --------+----------/o--------+--------- To load ! ! ! !o ! V Button --! ! --- !o-+--->!-------------+ ! ! ! ! ------------------- +--! Power Logic ! ! ------------------- / \\ / 1M ! GND

The power logic is only powered on if the semiconductor switch is on or is the button is pressed.

Another way to go is to make the power logic out of a CD4000 series IC and leave the power on it.

The delay can be as simple as a RC circuit that is discharged any time the button is not pressed. Like this:

----!-------+---/\\/\\---+---+--- !/ ! buffer === ! GND

You can get CD4000 logic that has Schmit trigger inputs.

Reply to
MooseFET

The obvious way to me would be a push button and RC network going into a Schmit trigger, driving a CMOS Dff. You can now make the turn on and turn off times different, depending on the state of the FF. As a first approximation 1S is 1 ufd and 1 meg.

Tam

Reply to
Tam

Not if you have the slightest clue, Google Grouper.

formatting link
*-*-4-ways+monospaced-*+To.read.ASCII.prints.from.Google+zzz+Before+%26fwc-*+Show.original+Fixed.text+Notepad+Proportional-*&fwc= snipped-for-privacy@e10g2000prf.googlegroups.com

Reply to
JeffM

Hope is all you have apparently since anything even remotely approaching analytical thinking is beyond your reach. That is a very confused question full of superlatives, non sequiturs, and other problems: "you've seen this (which does that) *but* you're hoping for that by not using this." Give us a break...

Reply to
Fred Bloggs
[snip]

Yes, Fred, Please!

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

formatting link
| 1962 | America: Land of the Free, Because of the Brave

Reply to
Jim Thompson

s off,

so

Reach for THIS, bone-head.

You have certainly dashed any hopes I HAD.....

Reply to
Paul

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.