Turn solenoid on for 1 sec only

[Girl0090]

Hi everyone,

I am working on a project that requires me to turn on a solenoid for one second only. I was using a 555 timer in a monostable setup and had it working but it has since stopped. My understanding of a 555 timer is that if once you take the trigger to ground the output remains high until you return the trigger to high (via say a 10k resistor). What i want to do is take the trigger to ground, thus setting the output to high, and then 1 sec later returning the output to low, regardless of weather the trigger is still grounded.

I am trying to switch a transistor IRF640 on with one second of +5v to its gate which turns on a solenoid for one second.

Any advice would be great

Thanks!

T

 

[ericgibbs]

Hi everyone,

I am working on a project that requires me to turn on a solenoid for one second only. I was using a 555 timer in a monostable setup and had it working but it has since stopped. My understanding of a 555 timer is that if once you take the trigger to ground the output remains high until you return the trigger to high (via say a 10k resistor). What i want to do is take the trigger to ground, thus setting the output to high, and then 1 sec later returning the output to low, regardless of weather the trigger is still grounded.

I am trying to switch a transistor IRF640 on with one second of +5v to its gate which turns on a solenoid for one second.

Any advice would be great

Thanks!

T

hi,
The 555 configuration you require is for a monostable, look at the 555 datasheet it has applications for monostables.

 

[Girl0090]

solenoid on for 1 sec only

That is pretty much what I have been using but I need it to turn the transistor off after one second (go LOW) it doesn't do that in monostable does it?

I am creating switch that when stood on, for say 5 seconds, takes pin 2 of the 555 to ground, turns the solenoid on for one second, then off after one second. my understanding is this is not what happens in monostable mode.

thanks for the snappy reply

T

 

[ericgibbs]

That is pretty much what I have been using but I need it to turn the transistor off after one second (go LOW) it doesn't do that in monostable does it?

I am creating switch that when stood on, for say 5 seconds, takes pin 2 of the 555 to ground, turns the solenoid on for one second, then off after one second. my understanding is this is not what happens in monostable mode.

thanks for the snappy reply

T

hi,
The basics of a monostable ,[ stable only in one state, ie ;OFF] is such that when triggered the 555 output will go high, it remain high for approx the time constant of the Res/Cap timing circuit, At the end of the timing period the 555 output will go low and remain low until the 555 receives another external trigger pulse.

To get more complex timing sequences two or more 555's can be connected in series.

Does this help?

 

[ericgibbs]

That is pretty much what I have been using but I need it to turn the transistor off after one second (go LOW) it doesn't do that in monostable does it?

I am creating switch that when stood on, for say 5 seconds,
When stood on, monostable #1 is triggered, it has a 5sec ON time, if at the end of the 5sec period the item is still stood on, a second monostable, having a 1 sec period is triggered and the solenoid operates...

Is this what you mean?

takes pin 2 of the 555 to ground, turns the solenoid on for one second, then off after one second. my understanding is this is not what happens in monostable mode.

thanks for the snappy reply

T

hi,
More detail.

 

[Girl0090]

to put it in real terms is easier to understand...

i am designing a simulation mine field for a charity org and need to trigger a 12v solenoid for 1 second to fire some powder into the air... i was going to use a momentary push button switch that could be stood on for some time... so as not to burn the solenoid it needs to turn off after about 1 second

 

[audioguru]

Pin 2 must be high again for the monostable to time out. You can capacitor-couple a short duration low-going pulse to pin 2 for triggering and have a pullup resistor on pin 2 to make certain that it times out if the input signal is still low.

 

[ericgibbs]

to put it in real terms is easier to understand...

i am designing a simulation mine field for a charity org and need to trigger a 12v solenoid for 1 second to fire some powder into the air... i was going to use a momentary push button switch that could be stood on for some time... so as not to burn the solenoid it needs to turn off after about 1 second

Something like this sequence?

If he/she gets OFF the switch before 5 sec, do you still want the 1Sec?

 

[Girl0090]

solenoid on for 1 sec only

my circuit is not using trigger pulses it uses a momentary switch that could be on for more than the time of the time constant of the Res/Cap.

 

[ericgibbs]

my circuit is not using trigger pulses it uses a momentary switch that could be on for more than the time of the time constant of the Res/Cap.

The closing of the switch would be connected to a C/R differentiator which will generate the trigger pulse
[once only] when the momentary switch is pushed.

Are you going to design and build this circuit?

 

[Girl0090]

Hi again,

Here is a graph to illustrate both scenarios.

if it helps...

 

[Girl0090]

yeah for sure i have tested it on a bread board and want to put it on a prototype for the installation...

Are you saying put the switch inbetween pins 6 and 7 of the 555...


thanks for all your help

 

[ericgibbs]

yeah for sure i have tested it on a bread board and want to put it on a prototype for the installation...

Are you saying put the switch inbetween pins 6 and 7 of the 555...


thanks for all your help

hi,
Please post your circuit, so that we can give you the correct advice.

 

[Girl0090]

solenoid on for 1 sec only

Here is the circuit i am really familiar with... it is a simple monostable circuit... should i use pull up resistors on a capacitor from pin 2? I have no idea what that does but maybe it is on the right track?

Thanks,

T

 

[audioguru]

I Eric,
I have looked all over the place for the explanation of the pin 2 voltage requirement for it to time out, that you posted.

It is too bad you saved and posted it as a fuzzy JPG file type instead of as a very clear GIF or PNG file type.
I made it black and white to eliminate its colourful bits but it is still fuzzy.

 

[ericgibbs]

hi,
Its getting closer!.

Build this extra bit, then get the 5 Second timing correct.

 

[ericgibbs]

I Eric,
I have looked all over the place for the explanation of the pin 2 voltage requirement for it to time out, that you posted.

It is too bad you saved and posted it as a fuzzy JPG file type instead of as a very clear GIF or PNG file type.
I made it black and white to eliminate its colourful bits but it is still fuzzy.

Attached ne555.pdf, is this what you mean?

 

[Girl0090]

Great I will give it a shot... thank you so much for your help... i will let you know how it goes!

 

[ericgibbs]

Great I will give it a shot... thank you so much for your help... i will let you know how it goes!

hi,
Next stage, to keep it simple its almost identical to the 1st stage.

 

[audioguru]

Thanks Eric,
I knew that Signetics invented the 555 then was taken over by Philips. I should have looked on their datasheet for the info. I have the Signetics databook somewhere in my library.

I copied the PDF page as a very clear PNG file type. It uses fewer bytes than your fuzzy JPG file type copy.