Time delay latch-thingy

Hiya

I've got a scenario where I want to power-up a 12V supply for (say for ~60 seconds) based on a momentary supply of 9V current (basically I want a doorbell push to turn on a small LCD monitor)

Its been a while since I've played with breadboards, but it strikes me as something straightforward but googling for components has drawn up a blank.

Anybody got any pointers?

Cheers

Colin

Reply to
Colin Chaplin
Loading thread data ...

RS sell a wide range of plug-in timers...

Reply to
Huge

Sounds like a nice job for a 555 based monostable (single shot) application. See the ten minute timer circuit here:

formatting link
need to tweak the cap size for 1 min obviously)

Reply to
John Rumm

A 555 timer chip plus a relay would be my option. If you pop along to the RS site you can download a PDF of the data sheet with circuit diagrams that should give what you want.

Reply to
Dave Plowman (News)

Ahh, that'd be the ticket... takes me back a few years!

However, I think I've come up with a better idea of using a PIR sensor, but I may yet choose this.

Thanks for your help guys.

Reply to
Colin Chaplin

Reply to
Owain

If you don't want to make one,

formatting link
up to 40s.

If you do, Velleman K2579 from Maplin does up to 15 mins

Owain

Reply to
Owain

Colin Chaplin presented the following explanation :

A 555 timer IC will do that, combined with a small relay.

Reply to
Harry Bloomfield

On Tue, 8 May 2007 10:47:15 +0100, "Colin Chaplin" mused:

Why not just use a relay with a delay timer built in?

Reply to
Lurch

Did something similar for my brother and his outdoor model railway to light track lights.

Basically just use a diode and capacitor (+small value resistor to limit capacitor current) and connect low current relay across capacitor. Applying

9V to diode charges the capacitor instantly'ish, relay closes. With 9V removed capacitor holds charge and relay remains closed. Relay discharges capacitor and after say 60s relay opens. Choose as low current relay as possible and vary capacitor value to get required hold time. He got all the bits from Maplin.
Reply to
Ian_m

HomeOwnersHub 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.