# Ne555p problems. Inexperienced. Help..

#### dl324

Joined Mar 30, 2015
11,527
The only difference is R1 is 2kohm and R2 is 100kohm.
I don't see a red or orange band:

#### dl324

Joined Mar 30, 2015
11,527
This is my worry that I spent 4 days now going crazy and its faulty hardware.
Now you need to build a jig and test all of them. You'll be lucky if they're even 555 timers. The counterfeiters only care about package.

Can you post some well focused high resolution of some of the parts? You can usually tell if they've sandblasted the top and remarked. You shouldn't see any pitting on the shoulders of the leads.
However besides acehardware I have no idea where to source electronic components. Any suggestions?
Ace isn't on my list for electronic components.

I'd use Jameco, Newark, Mouser, or Tayda. A lot of people like DigiKey, but, for some reason, I don't. I'm of the opinion that their prices are higher because they carry a large inventory.

Don't buy from Ali Express, Banggood, or any place in China. You're almost guaranteed to get counterfeit parts.

#### Bbrandonparran

Joined Sep 8, 2020
24
I don't see a red or orange band:
View attachment 216759
Fantastic. They're probably inaccurate. These came in my breadboard kit and I've been using the labels on the bags for reference. I have no way of confirming the resistance until I get my multimeter in. I'm ordering new ICs from mouser and I'll have a oscilloscope and multimeter this weekend and I'm just going to start from the top.
Not trying to waste anyone's time being the noob I am

#### Chris65536

Joined Nov 11, 2019
225
I'm ordering new ICs from mouser and I'll have a oscilloscope and multimeter this weekend and I'm just going to start from the top.
Excellent. Keep us posted!

#### dl324

Joined Mar 30, 2015
11,527
They're probably inaccurate.
They look like 1% resistors.

2k = red black black brown (2 0 0 1 = 200 * 10^1)
100k = brown black black orange (1 0 0 3 = 100 * 10^3)

1% resistors use a 5 band code.

Sometimes it's difficult to tell which end to start reading from, but there are some numbers that aren't valid in certain positions and that gives you a clue.

#### MrChips

Joined Oct 2, 2009
21,868
Put the 10μF in between Vcc and GND and leave it in permanently. It is a required part of the circuit. You don't have an option.
Does the circuit function correctly with it in place?

#### Bbrandonparran

Joined Sep 8, 2020
24
Now you need to build a jig and test all of them. You'll be lucky if they're even 555 timers. The counterfeiters only care about package.

Can you post some well focused high resolution of some of the parts? You can usually tell if they've sandblasted the top and remarked. You shouldn't see any pitting on the shoulders of the leads.
Ace isn't on my list for electronic components.

I'd use Jameco, Newark, Mouser, or Tayda. A lot of people like DigiKey, but, for some reason, I don't. I'm of the opinion that their prices are higher because they carry a large inventory.

Don't buy from Ali Express, Banggood, or any place in China. You're almost guaranteed to get counterfeit parts.
Best I could get with the lighting and my phone sorry.
Left is the original 555 that I got and i had effed up and shorted out. Now it gets extremely hot when plugged in. So I got a set (right) which closer inspection it doesnt look pitted but it does look scraped in some way. You can tell an obvious difference in quality. I'm marking this as faulty equipment because inhave no way of proving other wise and I've tried EVERY astable setup I've found on line with EVERY combination of resistors I have. And it does not give me any useable clock pulse.

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#### Bbrandonparran

Joined Sep 8, 2020
24
Put the 10μF in between Vcc and GND and leave it in permanently. It is a required part of the circuit. You don't have an option.
Does the circuit function correctly with it in place?
I leave it in place I thought it was useful info to say I could remove it with out affecting the 555 output

#### Bbrandonparran

Joined Sep 8, 2020
24
They look like 1% resistors.

2k = red black black brown (2 0 0 1 = 200 * 10^1)
100k = brown black black orange (1 0 0 3 = 100 * 10^3)

1% resistors use a 5 band code.

View attachment 216763

Sometimes it's difficult to tell which end to start reading from, but there are some numbers that aren't valid in certain positions and that gives you a clue.
This matches the chart provided with my resistors and I'm looking and seeing that the labels do not match up.. I'm gonna give this a rest until I get some way to verify with my multimeter.

#### dl324

Joined Mar 30, 2015
11,527
I leave it in place I thought it was useful info to say I could remove it with out affecting the 555 output
With all of this shoot through and decoupling cap back and forth, I decided to do a test.

I breadboarded a 555 timer (TI NE555P) using 4.7k resistors and a 220uF cap that I had handy. That should give me a frequency of about 0.5Hz.

The circuit is working using a bipolar timer, a 5.2V supply with around 40mV of ripple, and no supply bypass cap. A cap on the supply won't hurt, but in my case, it's unnecessary.

I put my DSO138 on the timing cap and the scope doesn't load the node appreciably. You can see that the capacitor voltage varies between 1/3 and 2/3 of VCC as expected. The scope is by no means what I'd call "good", but it's sufficient and saves wear and tear on my vintage Tek CRT scopes.

Sorry for the crappy image. I needed flash and didn't want the glare on the screen, so I took it at an angle.

#### MrChips

Joined Oct 2, 2009
21,868
If you have ever worked often enough with NE555 timer ICs you will come to understand why decoupling capacitors are not optional.

#### Bbrandonparran

Joined Sep 8, 2020
24
With all of this shoot through and decoupling cap back and forth, I decided to do a test.

I breadboarded a 555 timer (TI NE555P) using 4.7k resistors and a 220uF cap that I had handy. That should give me a frequency of about 0.5Hz.

The circuit is working using a bipolar timer, a 5.2V supply with around 40mV of ripple, and no supply bypass cap. A cap on the supply won't hurt, but in my case, it's unnecessary.

I put my DSO138 on the timing cap and the scope doesn't load the node appreciably. You can see that the capacitor voltage varies between 1/3 and 2/3 of VCC as expected. The scope is by no means what I'd call "good", but it's sufficient and saves wear and tear on my vintage Tek CRT scopes.
View attachment 216770
Sorry for the crappy image. I needed flash and didn't want the glare on the screen, so I took it at an angle.
The highest cap I have currently is 100uf. And to be clear your using 2 - 4.7k resistors for the timing? I noticed a difference last night when I used two of the same resistance resistors but it still was not an reasonable cycle. I believe it would have been about a 90% duty cycle? On for 90% of the time and just a quick flicker off. Correct me if I'm wrong. That's just what my eyes were seeing

#### dl324

Joined Mar 30, 2015
11,527
Best I could get with the lighting and my phone sorry.
Guess no one uses real cameras these days. A clearly focused picture with a large F-stop would give a good depth of field.

That's the saddest TI logo I've ever seen. Both appear to be counterfeits. If you look at the texture on top, bottom, and sides, it should be uniform because the package is molded. The leads should be shiny; yours look like they might be textured from sand blasting.

Here's an authentic part from the late 70's/early 80's:

#### dl324

Joined Mar 30, 2015
11,527
The highest cap I have currently is 100uf. And to be clear your using 2 - 4.7k resistors for the timing?
Use 2 10k resistors and the frequency will be
$$f=\frac{1.44}{(R_A + 2R_B)C}=\frac{1.44}{30k*100uF}=0.48Hz$$

You could have determined that the frequency would be about the same because you'd be doubling the resistance and halving the capacitance.

No supply bypass cap and no cap bypassing the control pin to ground. Both are recommended, but clearly not mandatory in all cases.

#### Chris65536

Joined Nov 11, 2019
225
That's the saddest TI logo I've ever seen. Both appear to be counterfeits.
That's what I thought too. Is the logo on the left actually supposed to be Texas!?

#### dl324

Joined Mar 30, 2015
11,527
I noticed a difference last night when I used two of the same resistance resistors but it still was not an reasonable cycle. I believe it would have been about a 90% duty cycle?

$$t_{ON}=0.693(R_A+R_B)C=0.693*(4.7k+4.7k)*220uF=1.43s$$
$$t_{OFF}=0.693R_BC=0.693*4.7k*220uF=0.72s$$

EDIT: corrected typo; & instead of %.

Last edited:

#### dl324

Joined Mar 30, 2015
11,527
That's what I thought too. Is the logo on the left actually supposed to be Texas!?
Yes, it's supposed to be the state of Texas. The 'i' sometimes appeared as a man/boy.

#### SamR

Joined Mar 19, 2019
2,580
I have learned that upon receiving ICs from Amazon, fleaBay, or AliX that I have to test them. One batch of 15 555s had over half of them fail using a simple test circuit. They did reimburse me for the entire lot but it is the price you pay for cheap components.

#### Bbrandonparran

Joined Sep 8, 2020
24
Guess no one uses real cameras these days. A clearly focused picture with a large F-stop would give a good depth of field.
View attachment 216778
That's the saddest TI logo I've ever seen. Both appear to be counterfeits. If you look at the texture on top, bottom, and sides, it should be uniform because the package is molded. The leads should be shiny; yours look like they might be textured from sand blasting.

Here's an authentic part from the late 70's/early 80's:
View attachment 216779
Lol my only camera is from 2005 would be much worse lol. And yeah they are definitely matt/satin not shiny. The ones on the right actually have excess plastic molding at the seem on some of them. Starting to really believe these are my issue. Very frustrating but I have 10 coming from mouser on friday