The most simple delay..

[ikalogic]

hello,
i need a method to provide output voltage x minutes after a switch closes the circuit.

the accuracy of x is not very important, do i have to use those 555 timers and etc.. or there is a more simple way like using capacitors, etc...???

i need the most simple way to provide that delay.

 

[mozikluv]

delay circuit

hi ikalogic,

since you did not specify what voltage you would like to use to drive what ever device is attach and you also want not to use the famous 555, how about using an SCR so you would have more leeway on the drive voltage. the timing is quite similar to the 555.

 

[dingo]

yes a cap and resistor will work as a time delay but to read it you may need a gate input anyhow.

 

[Nigel Goodwin]

The main problem here is 'x minutes', to get delays in the minutes you need large value capacitors and large value resistors, this means it requires a high impedance trigger circuit.

The formula for charging time is T=CR - where T is in seconds, C in farads, and R in ohms. So 1uF and 1Mohm would give 1 second, 60uF and 1Mohm would give 1 minute (in theory! - in practice large electrolytic capacitors tend to be fairly leaky and mess your timings up).

Certainly a 555 timer seems about as simple as you are going to get, it's designed for the job and makes it easy.

 

[ikalogic]

okay! gr8!
i just bought a couple of 555 timers..and i played with them to get my self more familiar wih it...
but it seems all i can get is (for example in a tone generator) a tone of say 5 seconds then no tone for 2 seconds, then tone again for 5 seconds, etc, etc,

actualy what i need is the best described by the folowing simulation
1-you press on a switch, or release a switch, or what ever
2-you wait for x minutes
3-after the x minutes passed, give an output voltage to drive another circuit.

but i dont want this precesus to repeat to infinity...

how can i do that (so, can 555 do that?)

thx for your help all.

 

[panic mode]

**broken link removed**

 

[Barry]

Hello all,
You may find this link useful : **broken link removed**
or even this link could help for some ideas : **broken link removed**
cheers,
Barry.

 

[mozikluv]

simple delay

hi,

now that you have the 555, you can configure that in a monostable mode (one shot) a have a turn on delay of whatever time you like, the SCR to turn on whatever device you connect. so when the 555 turns off the SCR remains conducting to keep the attach device remain on. the only way to stop operation is to cut power to the system.

the next problem is, do you know how to connect the SCR to the 555 and have it triggered with the correct trigger current/voltage?

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