I am wondering if there is a switch out there that can acomplish the following:

I have a device powered by a 9v battery. I want to be able to depress the switch and have a set delay of 3-7 seconds. At that time the switch opens allowing current to pass. Idealy the switch should be small and in-expensive.

Any ideas??

Thanks!

 

ok i have one ...
* goes off to design room*

 

you want to be able to turn the device off ..Right ?..lol

 

is two IC's and a N-channel FET..some resitors and cap's too complicated ??
to this circuit , you could hook up a 555 timer then have the output go to the FET turning on your device..
the circuit can also be operated off of 9V.
EDIT : revised circuit..

Attached Images

on_off_circiut.jpg (17.6 KB, 943 views)

 

Thanks for the info williB. I do not have a tremendous amount of experience with circuit design. The schematic you posted looks relatively simple. The switch is for a smoke device (for paintball) I want to be able to hit the switch (triggering the time delay) then place it or throw it, and have the switch trigger the device after 3-7 seconds. Can you give me a written indication of how this circuit works?

Thanks again!

Steve

 

got a new circuit..
ok R1 & C1 set up the delay.
C2 is just a .1 uF cap.
R2 = 10K ohms
Q1 is any N-channel Mosfet
I tried 100K ohms for R1 & 5uF for C1. it came out to 5 . Seconds i think..
Time =1.1 (R1*C1)

Attached Images

untitled_2.jpg (24.5 KB, 887 views)

 

oh another thing
This curcuit works from 5 to 15 V.
about half way down the page is a Mono stable circuit..the one i used..
also this site has a calculator for astable operation( free running) so in mono stable mode the calculator wont be correct.

http://ourworld.compuserve.com/homep...Bowden/555.htm

 

williB can you PM me your email address, might make it easier?

 

sure ..
oh that big +sign just below the switch was part of Eagle Software pgm i forgot to get rid of it..

 

Ya know if you are going to test the circuit with a LED ., ya need a current limiting resistor in the drain current path..
but the current limiter is not needed when you hook in your circuit to mine..

 

sorry
page two

http://www.jameco.com/wcsstore/Jamec...797Philips.pdf

 

You could do this with a relay, capacitor, button and switch.
Connect the cap across the relay coils. Press the button to operate the relay that will also charge the cap. Fick the switch while the button is in so when the relay closes the circuitit will be active.

You should easy get 10 seconds with a big enough cap and small relay.

 

Hey dingo, thanks for the reply! I am still working with williB on the 555 circuit, but there's more than one way to skin a cat! Do you have any suggestions on a specific relay or capacitor values?

 

well your relay is easy, find out what current draw you are using so you don't burn out the contacts. I am guessing that if you are only using a 9v batt a small reed relay would do.

connect the battery, cap and relay. Disconnect the battery and see how long the relay stays in. Try starting with a 220uf 16v electro and see if you need to go up or down in uf.

 

Ok I have prepared a schematic based on Dingo's suggestions (I have adjusted the voltage for now, the final circuit will be 9v) The file is attached.

Thoughts??

Steve.

Attached Images

timer_v1.jpg (17.3 KB, 729 views)