Electronics > Beginners
1 NE555 timer and 1 LED circuit question
Audioguru:
There are only TWO 555 spec's: The old bipolar one and the newer Cmos one.
The NE555 is made by many IC makers. Its max output current is 200mA. Its minimum supply voltage is 4.5V.
The Cmos one is made as LMC555, TLC555 and ICM7555 and is low power and has a low max output current, especially when its supply is 5V or less.
The LMC555 is guaranteed to work with a supply as low as 1.5V!
Arjunan M R:
--- Quote from: soldar on June 02, 2019, 02:46:23 pm ---"I once crossed the street without looking first and nothing bad happened." Bad advice.
"I text while driving and haven't had an accident yet." Bad advice.
--- Quote from: Arjunan M R on June 02, 2019, 02:31:31 pm ---I have also built your circuit don't even thinking about pin 5 and I had no problems :-//.
--- End quote ---
Bad advice.
Bad advice: costs nothing and it's worth the price. :)
--- End quote ---
I said so because I built this circuit a lot of times but I never had a problem =
I said so because I texted many times while driving and haven't had an accident yet. = bad advice :)
Sorry, removed the first two lines.
I was not aware of that I was posting it in the beginners section. :palm:
soldar:
--- Quote from: Arjunan M R on June 02, 2019, 02:51:53 pm --- Sorry, removed it .
--- End quote ---
Oh man, I did not intend to pick on you and I am sorry if it came across that way. I was just attempting a little humor.
All I meant is that it is better to follow good practices all the time. You can get a way with a lot but bad practices will catch up with you sooner or later.
Pin 5 of the 555 should not be left floating. It is better to put a capacitor that will avoid false triggers.
StillTrying:
With long power wires the 100nF to 10uF decoupling across a bipolar 555 power is more important than the Pin5 decoupling.
Just to add to the confusion. >:D
On a supply with high impeadance such as a half discharged battery, there are occasions when decoupling to Pin5 to GND when the timing or triggering is tied to V+ can make false triggering worse.
soldar:
Decoupling the power pins goes without saying. There, I said it.
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