| Electronics > Beginners |
| A one time timer |
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| Zero999:
Why use a 555? Real engineers use a discrete monostable. ;D If the trigger pulse is always shorter than the delay, then R4 and C2 are not needed: R4 should be open and C2 shorted. EDIT: I omitted R5, which is required to limit the base current through Q1, when C1 charges. Without it, nearly the full load current will pass through the base, potentially destroying it! |
| alsetalokin4017:
Real Engineers may use a discrete monostable, but many ordinary people just use what they have available in their junqueboxes. |
| Brumby:
I have no qualms about using any solution when it is capable of doing the job. If a 555 can do it - then why not? Besides ... the 555 has a very well deserved place in history and getting to implement one in a circuit can certainly be considered a right of passage. |
| james_s:
The 555 is a great part, but that doesn't mean it's the right tool for every job. When talking of delays of several minutes or more, there are better choices. |
| Brumby:
There may be "better" - but better how? Are they going to be better for the criteria: --- Quote from: iamashwin99 on May 29, 2018, 03:09:09 pm ---I dont need it to be precise, anything from 5-8min is acceptable. --- End quote --- The thing is - not to get too wound up with the latest and greatest or even some super-duper chip when an entirely satisfactory solution can be had with a 555. JMHO |
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