# delay on circuit

Discussion in 'General Electronics Discussion' started by RedDragon, Mar 17, 2012.

1. ### RedDragon

15
0
Mar 17, 2012
I need a delay on circuit for about 500ms with 5v

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,832
Jan 21, 2010
Perhaps you can explain more fully what you require.

Do you want the device to wait half a second after you switch it on before it actually powers up?

Or do you want it to remain turned on for only half a second after you turn it on?

Or something different?

We'll also need to know what the device is (probably) unless you simply need a logic level signal.

3. ### RedDragon

15
0
Mar 17, 2012
I need it so the input has to be on for at lease 500ms before there will be a output.

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,832
Jan 21, 2010
If this is a logic signal then you can solve this with a resistor, a capacitor and a Schmitt trigger (or 2 if you don't want an inverted output).

Check out the application notes. Look at figure 12 on the top of page 8. If you invert this (essentially change the position of the resistor and capacitor and point the diode the other way) it will do what you require. The appropriate formulae are provided so you can calculate values.

5. ### RedDragon

15
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Mar 17, 2012
it also needs to have a rating of 1 amp

6. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,832
Jan 21, 2010
Perhaps you can explain *fully* what you require.

(Because I'm not going to get lulled into the trap of repeatedly answering one set of requirements before you add another and another, ... ad naseum)

7. ### RedDragon

15
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Mar 17, 2012
Ok well I'm making a relay computer and i need a delay on circuit so that the input has to be on for at lease 500ms before there will be a output. the supply voltage is 5V and i need it to handles at less 500mA

8. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,490
2,832
Jan 21, 2010
Do you want this done with relays, or can we use electronics?

One "non-electronic" solution is to have a resistor in series with the relay coil (with a low enough resistance that the relay can still operate) and a large capacitor across the relay coil. That will delay the turn-on of the relay after power is applied. The relay should be able to switch 500mA.

9. ### RedDragon

15
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Mar 17, 2012
yes we can use electronics but I like that idea of yours using the relay so i will try that.

10. ### poor mystic

1,068
31
Apr 8, 2011
the capacitor will also delay release of the relay

11. ### RedDragon

15
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Mar 17, 2012
well that mite be ok if it not long

12. ### RedDragon

15
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Mar 17, 2012
no it didn't work. i got a delay but i do need it to turn off when the input turns off without a delay