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NE555p circuit help

billybob

Member
I have recently got 20 NE555p ics, and from what I found are the same as the commonly known 555 ic. I have tried sooooooo many simple oscillator designs for at least 3 hours it’s not even funny. I just cant figure out what Im doing wrong. Most circuits are very similar with only a slight resistor change. Here is one that I have tried multiple times on my breadboard. although it’s not the variable design I assume I can switch a resistor for a potentiometer. If anyone can provide some input on the design or an alternate schematic you will save me a lot of stress.
1611101967637.jpeg
 

sarahMCML

New Member
Try 5 Volts or more for your power supply as a standard 555 needs a minimum of 4.5 Volts. To run at a lower voltage you need a CMOS version of the chip.
 

crutschow

Well-Known Member
Most Helpful Member
Apparently someone failed to look at the data sheet. :rolleyes:
 

Visitor

Well-Known Member
Apparently someone failed to look at the data sheet. :rolleyes:
Billybob is a 16 year old (or so) kid just getting started in electronics. I'm certain he would appreciate your encouragement and guidance more than snide remarks.

Or some helpful advice, like searching for a part on octopart.com to quickly locate a datasheet, and to see distributors who have stock of a particular component. It's a handy resource.

Screenshot_20210120-015040_Edge.jpg
 
Last edited:

AnalogKid

Well-Known Member
Most Helpful Member
There is a reasons why the circuit will not work. On the datasheet, in the table of Electrical Characteristics, note the first item. Compare this to your schematic.

Note that this reason is not related to the distributor.

ak
 

DerStrom8

Super Moderator
In general you'll want the lower resistor (between pins 6 and 7) to be the higher value. As designed, your duty cycle is around 91.7%, so the output off-time will be very short. Since you've got your LED connected to turn on during the output off-time, there will only be a very short flicker (152ms).

Do read the datasheet though, there are other issues that should be taken into account before the above even matters.
 

gophert

Well-Known Member
Most Helpful Member
The circuit posted will turn on the LED for about 0.2 seconds every 2 seconds and it should be easy to see.
If you are not seeing it, try
- turning your LED around in case you mixed up anode and cathode
- checking voltage across pins 1 and 8 on your 555 chip in case your breadboard is defective or has a gap in the power rail that you are not aware of
- check if your timing capacitor is really 10uF.

DerStrom8 - the 555 will have a high output 90% of the time but the LEd will only be on 10% of the time since the anode is connected to Vcc (LED will be lit when 555 output is low).
 

DerStrom8

Super Moderator
The 555 will have a high output 90% of the time but the LEd will only be on 10% of the time since the anode is connected to Vcc (LED will be lit when 555 output is low).
That's why I said this:

Since you've got your LED connected to turn on during the output off-time, there will only be a very short flicker (152ms).
 

crutschow

Well-Known Member
Most Helpful Member
Billybob is a 16 year old (or so) kid just getting started in electronics.
Well, I don't look up the age of every poster.
Apparently you do.
And his age is no excuse for not looking at the data sheet for a device (which is readily found with a Google search) that he is trying to use, especially when it doesn't work as he expected.
 

Visitor

Well-Known Member
No, I just have read some of his posts where he has explained he's just getting started.

But a condescending reply is easier to post than a helpful one.
 

DerStrom8

Super Moderator
Well, I don't look up the age of every poster.
Apparently you do.
And his age is no excuse for not looking at the data sheet for a device (which is readily found with a Google search) that he is trying to use, especially when it doesn't work as he expected.
It's not so much a matter of looking at the age, but a matter of being kind towards others, especially considering they may be new to electronics and perhaps don't have much experience reading datasheets yet. It takes some practice to read and truly understand a datasheet.
 

Mickster

Well-Known Member
Most Helpful Member
In one of his posts a short while ago, he mentioned that he was at school.
 

simpleGuy

New Member
If he is a newbie to electronics he should definitely not start with a NE555 or any other opamp, thats way too complex to a "newbie".
But if he just wants to make a led "blink blink blink" with a NE555, there are tons of quick diy youtube videos.
 

DerStrom8

Super Moderator
If he is a newbie to electronics he should definitely not start with a NE555 or any other opamp, thats way too complex to a "newbie".
But if he just wants to make a led "blink blink blink" with a NE555, there are tons of quick diy youtube videos.
Are you kidding? 555 timers are an excellent introduction to ICs for newbies, and are most certainly NOT "too complex" :p
 

MacIntoshCZ

Active Member
If he is a newbie to electronics he should definitely not start with a NE555 or any other opamp, thats way too complex to a "newbie".
But if he just wants to make a led "blink blink blink" with a NE555, there are tons of quick diy youtube videos.
He is playing with few volts. If his power supply cant supply hundreds of amps as mine he should not be scared of anything.
Only his mother i guess =D.
BTW
I think i already post this to him
 

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