# Hey I Need help on a 555 2 second timer!

Discussion in 'General Electronics Chat' started by willtry, Jun 25, 2011.

1. ### willtry Thread Starter New Member

Jun 25, 2011
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0
Hi, I have a board that you throw bean bags at and when they go through the hole they hit a paddle I have made. The paddle goes on a standard light switch behind the hole. The paddle has a spring on it so that it will come back to its original position. Then when the switch moves it will activate a bell and light. I would like to have them both be on a timer so when the paddle comes back (it comes back right a way) that the bell and light stay on for about 2 to 3 seconds. I would like to be able to use a 555 timer. Does anybody have a diagram or something that would be helpful? I need to get this done and I would like it to be simple and cheap.

2. ### DerStrom8 Well-Known Member

Feb 20, 2011
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1,356
connect the switch between pin 2 of the 555 timer and ground, and use a 1K resistor for R1, 10K resistor for R2, and a 400uF capacitor for C. Use the first diagram in this image:

That will give you an on-time of roughly 3 seconds. Hope this helps!
Der Strom

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3. ### SgtWookie Expert

Jul 17, 2007
22,202
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DerStrom,
You're giving him values for R1 & R2, but only the astable circuit has an R1 & R2 - which won't do what the OP needs to do.

See the attached schematic; R1 and C1 are the timing components, giving a ~1 second ON time for the buzzer and LED. I used a much larger resistor and smaller capacitor of a standard value. If you really want ~2.2 seconds, increase R1 to 2 MEG.

Ignore V2 and the 2N7002; they simulate the closure of the switch for simulation purposes.

R3 and R4 were selected for a power supply of 10v. Since our OP has not stated what they are intending for use as a supply, they will do for the moment; but will be OK for ~6v to ~10v.

• ###### 555 One Shot 1 Sec.PNG
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Last edited: Jun 26, 2011
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4. ### DerStrom8 Well-Known Member

Feb 20, 2011
2,424
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Oh, I'm terribly sorry about that! Thank you very much for pointing that out, SgtWookie!

DS

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5. ### willtry Thread Starter New Member

Jun 25, 2011
3
0
Hey thanks for the info I'll see what I can come up with.

6. ### DrugCoder New Member

Jun 29, 2011
6
1
I was wondering if you could post a pic of your board with the paddle. I was interested in doing something similar but was considering using some kind of IR sensor to know if the beanbag has gone through the hole. Seems like unless you have a very weak spring the paddle might prevent some of the bags from falling through the hole if it's just creeping over the edge of the hole.

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7. ### willtry Thread Starter New Member

Jun 25, 2011
3
0
I know what you mean. I happen to have a very weak spring and the paddle is made out of steal, and it has a hole in it at the top that the spring is mounted to and that way I do not have to worry about the beanbags messing it up. And no I can not post a picture because I do not have a camera at the currant time. sorry about that. The light switch that I'm using has a lot of travel so that beanbags have to hit it pretty hard. I like your idea. Also the paddle is fairly big. So I do not have to worry about the beanbags just making it through. Enjoy!