Is it possible to identify if it's fake?

That's one of the ugliest TI logos I've seen. I'd say it's counterfeit. There's no dimple by pin 1. Are the shoulders of the leads grainy like they've been sandblasted? Is the texture of the top of the package the same as the bottom?

 

I'd say it's counterfeit. There's no dimple by pin 1. Are the shoulders of the leads grainy like they've been sandblasted? Is the texture of the top of the package the same as the bottom?

I have just done a search for TI 555's and had a look at several well known and reputable authorised dealers and companies (I won't mention their names) and it seems that some 555's do not have dimples at pin 1.
So I'm not certain if the 555's I have are fake or genuine.
Here are 2x screenshots of 555's from reputable companies...

 

some mosfets have input protection clamp - such as if you insert too high voltage it gets shunted to GND ??

this one IRF530 obviously has not nor is it's Vgate out of limits ... ??? is your mosfet pinout correct ???

+ there is a known gradual gate oxide failing mechanism that would be more likely if the mosfet is at heavy duty circuit where the voltages and temperatures approach these listed in the Abs. Max. ratings section of the datasheet (or if it's taken out ouf such cicuit) . . . but then your LED woudn't get ON - i guess (or you never know if it takes 5..6 minutes to get hot)
= measure the device (555) current from both sides Vcc and Vee power inputs

 

some mosfets have input protection clamp - such as if you insert too high voltage it gets shunted to GND ??

this one IRF530 obviously has not nor is it's Vgate out of limits ... ??? is your mosfet pinout correct ???

+ there is a known gradual gate oxide failing mechanism that would be more likely if the mosfet is at heavy duty circuit where the voltages and temperatures approach these listed in the Abs. Max. ratings section of the datasheet (or if it's taken out ouf such cicuit) . . . but then your LED woudn't get ON - i guess (or you never know if it takes 5..6 minutes to get hot)
= measure the device (555) current from both sides Vcc and Vee power inputs

As I have mentioned, I have removed the MOSFET but the 555 is still getting hot.

 

At this point, the NE555 is toast. Move on. They are pretty hardy but I have had some chinesium trade that were dead on arrival. I now test all parts that I receive from china and about 10% fail. I do get my money back but the 4-6 delivery time (or not at all) and time spent testing and applying for refund is not something I would do except as a hobby. Parts are cheap, most are good, but there is a high level of frustration to deal with. I have become convinced that when companies sell their off-spec trash as electrical scrap they get bought and sorted in china for resale by people who have absolutely zero knowledge of electronics. Simply trying to change a pig's ear into a silk purse. FWIW

 

I have just done a search for TI 555's and had a look at several well known and reputable authorised dealers and companies (I won't mention their names) and it seems that some 555's do not have dimples at pin 1.

Here's a photo of a TI NE555 from the late 70's or early 80's.


Look closely where I've drawn a red line. The package texture and color should be uniform because it's formed in a mold. That's how the pin 1 dimple is formed. Counterfeits will sand the top and apply a blacktop. The shoulders of the leads look to have been sandblasted to me.

 

At this point, the NE555 is toast. Move on. They are pretty hardy but I have had some chinesium trade that were dead on arrival. I now test all parts that I receive from china and about 10% fail. I do get my money back but the 4-6 delivery time (or not at all) and time spent testing and applying for refund is not something I would do except as a hobby. Parts are cheap, most are good, but there is a high level of frustration to deal with. I have become convinced that when companies sell their off-spec trash as electrical scrap they get bought and sorted in china for resale by people who have absolutely zero knowledge of electronics. Simply trying to change a pig's ear into a silk purse. FWIW

Yes, I understand what you mean. I have also obtained items from China and I have received some items that have been damaged or defective.
I seem to think that the 555's were from a reputable UK dealer (possibly RS Components) but that was many years ago.
At this point I have decided to move on and start again.

 

Just to let you know that it was the 555 that was faulty. I got hold of some good quality 555's and the circiut is now working fine.

 

No, I haven't replaced the 555 IC and could be difficult because I didn't use a IC socket. I will make a new circuit board and try again.



True, as Bertus said, there is no problem with pin 7 not being connected.
My circuit has a 50% duty cycle with an equal mark/space ratio.
(Picture courtesy of Electronics Tutorials website)

View attachment 215410

Total time (T) = 2 x 0.693 x R x C
So in my circuit the total cycle time is T and so..
T = 2 x 0.693 x 220,000 x 0.0001
T = 1.386 x 220,000 x 0.0001
T = 1.386 x 22
T = 30.492 seconds
Ie. The output cycles about 30.492 seconds (LED is 15.246 off and 15.246 on).
I have disconnected the MOSFET but does not seem to make any difference..(the 555 is still getting hot).

I would not have thought lowering the resistor value would affect the 555 operation.

Make sure you're using the correct capacitors. In your first post, you're showing polarized capacitors, which can cause a negative feedback through the 555. IN the drawing above, they are non-polarized. I'm not saying either is right- you need to rely on the datasheet to be sure you use the correct one in each place.

 

I have just done a search for TI 555's and had a look at several well known and reputable authorised dealers and companies (I won't mention their names) and it seems that some 555's do not have dimples at pin 1.
So I'm not certain if the 555's I have are fake or genuine.
Here are 2x screenshots of 555's from reputable companies...
View attachment 215429View attachment 215430

You don't need a dimple at pin 1- the fact that a notch is taken out of the top identifies pin 1 to be first pin on left of notch. I'm not making any remark about counterfeit or not; just saying that they don't always specifically mark pin 1.

 

Just to let you know that it was the 555 that was faulty. I got hold of some good quality 555's and the circiut is now working fine.

Good deal!

 

You don't need a dimple at pin 1- the fact that a notch is taken out of the top identifies pin 1 to be first pin on left of notch. I'm not making any remark about counterfeit or not; just saying that they don't always specifically mark pin 1.

Yes, I've discovered that. These are the new 555's I've got and they seem to be ok.

 

Make sure you're using the correct capacitors. In your first post, you're showing polarized capacitors, which can cause a negative feedback through the 555. IN the drawing above, they are non-polarized. I'm not saying either is right- you need to rely on the datasheet to be sure you use the correct one in each place.

If you do not recommend polarised capacitors, what value and type of capacitors could I use in the circiut to produce the same/similar timings?

 

Plain ole ceramic disc caps

 

Make sure you're using the correct capacitors. In your first post, you're showing polarized capacitors, which can cause a negative feedback through the 555.

Can you please explain that.

 

Plain ole ceramic disc caps

Ok, so what value of ceramic capacitor can I use in the circuit shown in post 1 to give a total time of 30.49 seconds?
I can only seem to find ceramic capacitors go up to about 2.2uF, this would mean I would have to use a 10M ohm resistor.

 

Ford, before you waste your time looking for a non-polarized timing cap, let BoBa explain his remark.

 

this would mean I would have to use a 10M ohm resistor.

10M is about the max resistance for a NE555. There is nothing wrong using polarized capacitors when trying to achieve long time delays. It's about the "leakage" in the capacitor that is often the limiting factor. Use a tantalum type electrolytic for your timing cap

 

These are the new 555's I've got and they seem to be ok.

It looks suspicious to me. The package is molded, so the texture seems off. Is it painted? Does the bottom have the same texture?

 

It looks suspicious to me. The package is molded, so the texture seems off. Is it painted? Does the bottom have the same texture?

These 555's seem to work quite well, as far as I can see there is not a problem. I was promised that these 555's are excellent and 100% quality...but then I suppose all sellers would say this even if they're rubbish! We will see...