LED delay IC, help needed

Hello guys

I'm have not much knowlage about small intigrated circuits so i hope someone can help me out.

I am a skydiver and we have this electronic automatic activation device (AAD) in our parachutes, i have the contol unit of the AAD and would like to make a keychain out of it but still keep the "look and feel" of it. It has a LED and a button on it and my goal is to make a very compact circuit which i can store inside.

Function wise it should be so when you press the button, that about 2 seconds later the led lights up once for about half a second. below there's a link of how the real thing operates, i want something that looks and acts the same, but only without the LCD screen, only the led after you press the button.

is there any kind of IC that can realise this function? the caseing is really small, i think a 3 volt button cell battery should fit inside tho.

here the link
https://www.youtube.com/watch?v=E_L_G8v-ImU
turning on the AAD starts at 1:10, i'm looking to have the same LED behavior without the cable going out from the control unit.

Hope my english is not too bad and hope i might get some help

thanks

Hi,

Ther are many solutions.
One can use analog comparators and some R and C.
Or you can use a small microcontroller like ATTINY and write a little software.

It depends on your skills and your needs. With R and C it may be more easy, but a microcontroler may be more precise and can give you other benifits..

Hope this helps
Klaus

Here is a simple way to do the job, with a power supply of 3V.

Throw the switch, 2 seconds go by, then the led lights briefly.

The scope trace shows the time frame is 2.2 seconds.



The switch must be turned off afterward. If you forget, the battery will eventually be drained.

The 1M resistors are needed to discharge the capacitors (which might take a few minutes). This resets the circuit for the next use.

The largest component is a 4,000 uF capacitor (or 5,000 or 6,000 if you wish). It charges to 1.2V, allowing the rating to be a few volts, which comes in a smaller size.