First of all, I would like to say hello. This is my first post here, so I am looking forward to asking all kinds of silly questions. I am trying to accomplish what I believe to be a simple task. Unfortunately, my understanding and knowledge of circuit design is limited. I have a basic knowledge of what the individual components are, but as far as designing what I want, I've got nothing.
That said, I am looking to build a "time delay" relay. The circuit must accomplish the following things:
1. 12V DC is the trigger voltage
2. When 12V DC trigger is removed, 12V DC is still output from the circuit for a period of time of about 3 seconds fixed (adjustable between 1-10 seconds would be perfect though)
3. Ignores other trigger inputs during operation
4. Self "resetting" so it will do the same timed operation upon receiving the next trigger signal
5. Drive a relay with a 300 mA 12V DC coil
6. Status LED to show when the circuit is operating. (I have 12V DC built-in resistor LEDs on hand)
I have looked at quite a few "one shot" monostable 555 circuits, but unfortunately I just don't know which one is right. Am I correct in assuming there is more than one way to skin a cat on this subject? Obviously the time is accomplished by a combination of resistance and capacitance in most instances, so I know there are variations there, but I am seeing circuits that supposedly accomplish the same thing with various things hooked up to different pins on the 555 too. Not to mention most circuits I have seen look to use a low input on the 555 to trigger it, I need a high input trigger (or a way to convert a high input trigger to a low input).
I guess I just want to know what the "right way" is to accomplish what I'm doing. I bought an "off the shelf" timer kit for $8 using a 555 timer at a local electronics shop to kind of "brush up" on what was going on, but it's an "intermittent" (bistable?) circuit (has adjustable delay for on time and off time via two pots) so it won't work. Well, that and I can't figure out how to take what I have and convert it into something that does what I want. Good news is, I have some bits and pieces I can use to build something new. I'm also not against buying new parts either of course.
So, if that's not too much to ask for a first post, I would greatly appreciate any and all help on this matter. Thank you in advance!
~T.J.
That said, I am looking to build a "time delay" relay. The circuit must accomplish the following things:
1. 12V DC is the trigger voltage
2. When 12V DC trigger is removed, 12V DC is still output from the circuit for a period of time of about 3 seconds fixed (adjustable between 1-10 seconds would be perfect though)
3. Ignores other trigger inputs during operation
4. Self "resetting" so it will do the same timed operation upon receiving the next trigger signal
5. Drive a relay with a 300 mA 12V DC coil
6. Status LED to show when the circuit is operating. (I have 12V DC built-in resistor LEDs on hand)
I have looked at quite a few "one shot" monostable 555 circuits, but unfortunately I just don't know which one is right. Am I correct in assuming there is more than one way to skin a cat on this subject? Obviously the time is accomplished by a combination of resistance and capacitance in most instances, so I know there are variations there, but I am seeing circuits that supposedly accomplish the same thing with various things hooked up to different pins on the 555 too. Not to mention most circuits I have seen look to use a low input on the 555 to trigger it, I need a high input trigger (or a way to convert a high input trigger to a low input).
I guess I just want to know what the "right way" is to accomplish what I'm doing. I bought an "off the shelf" timer kit for $8 using a 555 timer at a local electronics shop to kind of "brush up" on what was going on, but it's an "intermittent" (bistable?) circuit (has adjustable delay for on time and off time via two pots) so it won't work. Well, that and I can't figure out how to take what I have and convert it into something that does what I want. Good news is, I have some bits and pieces I can use to build something new. I'm also not against buying new parts either of course.
So, if that's not too much to ask for a first post, I would greatly appreciate any and all help on this matter. Thank you in advance!
~T.J.