problem with 555

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hi
in astable mode of 555 i have square wave of 50% duty cycle.
i WANT TO use it for measure L of inductor but when i place my inductor ,square wave is gone.
why this is happening?

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Where, exactly, do you place your inductor?

 

And how do you determine that the square wave is "gone"?

 

Post a schematic - here's the instructions: https://www.avrfreaks.net/wiki/em...

 

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rest of circut is in astable mode

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Whats the frequency response of a serial L/C circuit?

 

 

Jim

 

 

(Possum Lodge oath) Quando omni flunkus, moritati.

"I thought growing old would take longer"

 

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"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

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ki0bk wrote:

Whats the frequency response of a serial L/C circuit?

 

 

Jim

 

frequency does not change. its 100 KHz and with LC serie it does'nt change just square wave is falling apart

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navidrct wrote:
square wave is falling apart

What does that mean??

 

Why did you not follow the instructions for inserting the schematic?

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first pic is one without LC series and another one is when we put LC on output

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awneil wrote:

 

navidrct wrote:

square wave is falling apart

 

What does that mean??

 

Why did you not follow the instructions for inserting the schematic?

IT IS ASTABLE MODE 555 CIRCUT THAT IS GIVING SQUARE WAVE.

PLZ SEE IT IN THIS

ITS MIDDLE ONE

 

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What did you expect?  Do you understand how an inductor works?

 

The inductor builds field strength as current flows through it.  The series cap means that when the 555 output goes high, the current starts high and then falls off as the cap charges up.  The current through the inductor stops, the field collapses, which induces a sharp spike of current in the opposite direction.  When the 555 toggles the output low, the cap discharges, again starting with a high current, building field strength in the inductor.  Once the cap is discharged, current stops, field collapses, sharp spike in opposite direction.  Rinse and repeat.

 

Sure looks like your second image...

 

There are lots of easy ways to measure the value of an inductor.  This is not one of them.  Did you follow the link I posted above?

 

Maybe have a look at some of these too:

https://www.google.ca/search?q=inductance+meter+arduino

"Experience is what enables you to recognise a mistake the second time you make it."

"Good judgement comes from experience.  Experience comes from bad judgement."

"Wisdom is always wont to arrive late, and to be a little approximate on first possession."

"When you hear hoofbeats, think horses, not unicorns."

"Fast.  Cheap.  Good.  Pick two."

"We see a lot of arses on handlebars around here." - [J Ekdahl]

 

Last Edited: Thu. Jun 11, 2015 - 02:11 PM
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joeymorin wrote:

What did you expect?  Do you understand how an inductor works?

 

The inductor builds field strength as current flows through it.  The series cap means that when the 555 output goes high, the current starts high and then falls off as the cap charges up.  The current through the inductor stops, the field collapses, which induces a sharp spike of current in the opposite direction.  When the 555 toggles the output low, the cap discharges, again starting with a high current, building field strength in the inductor.  Once the cap is discharged, current stops, field collapses, sharp spike in opposite direction.  Rinse and repeat.

 

Sure looks like your second image...

 

There are lots of easy ways to measure the value of an inductor.  This is not one of them.  Did you follow the link I posted above?

 

Maybe have a look at some of these too:

https://www.google.ca/search?q=inductance+meter+arduino

SEE the attachment . when inductor field collapes its goes throuth diods and it is working now

thanks alot

if any suggestion u have i will be greatfull to know

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Which country are you in? I just looked at "Inductance meter" on my local ebay and the cheapest meter is about £5. It's not surely worth trying to make up circuits when you can buy the ready made thing for virtually the same cost of the components you might need and you'll end up with something that's guaranteed to work and work reliably. If you build your own how do you actually know it's working right if you have nothing to check against?

 

(rhetorical: is it heresy to suggest such a move?!?)

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Navid,

Please stop using capital words (because it's pointless and we think you are shouting at us. then it's kinda rude) and don't use some childish words like "plz" or "wanna" and use capital "I" when you refer yourself and spend more times to write your posts. sounds like your grammer isn't so good. do you know why these guys here ask you "why don't you google it"?

because they think you can understand English but you don't want to search on internet. in other word, they think you are lazy. if you can understand English then why don't you post all things you want to do and what's your problem.

Why don't you follow the link that Joey has mentioned?

because blogspot is blocked in Iran then I converted that link to PDF. there you go:

 

http://vmaniac.com/files/apexys_toan_blogspot_ca_2011_02_ne555_based_inductivty_meter.pdf

 

clawson wrote:

Which country are you in?

Iran

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

Last Edited: Thu. Jun 11, 2015 - 02:38 PM
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clawson wrote:

Which country are you in? I just looked at "Inductance meter" on my local ebay and the cheapest meter is about £5. It's not surely worth trying to make up circuits when you can buy the ready made thing for virtually the same cost of the components you might need and you'll end up with something that's guaranteed to work and work reliably. If you build your own how do you actually know it's working right if you have nothing to check against?

 

(rhetorical: is it heresy to suggest such a move?!?)

actualy i WANT TO build one rlc meter.not with 555.

its like a practice to me.

inductance meter that cost only 5 euro is not reliable . i have one but its not accurate as i want it to be.

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Do you HONESTLY think something you cobble together with a 555 is going to be MORE reliable?!

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Get a handheld meter that reads L and C in addition to volts and ohms?

 

Imagecraft compiler user

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Elmcie is one uC inductor meter.

 

AN #172 Inductance Meter is another one.

 

Both might give you some good ideas about how others have done this.

 

JC

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clawson wrote:

Do you HONESTLY think something you cobble together with a 555 is going to be MORE reliable?!

well i have good oscop . and 555 give me good square wave . then y not?

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Just did a Google "how to measure inductance with a scope". There's a bit of reading.

You probably want a sine wave source, not a square wave.

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Kartman wrote:

Just did a Google "how to measure inductance with a scope". There's a bit of reading.

You probably want a sine wave source, not a square wave.


I want to measure L .for that I want di/dt.in squire wave I can do that .because inductor will smooth di little bit.
it's what's in my mind.
please if I'm wrong, tell me
thanks for answering

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And if you are going to use a square wave then what you have is not a square wave.  The tops are nasty.

This looks like you have a second signal at a very close frequency running through the trace - what is the cause of that?

David

 

 

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I don't know.should it change?y should it change?

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My guess is that you power don't handle the extra power when  the diodes open , very well

How good are the PSU, some good caps over GND and VCC near the 555 would probably help.

 

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I thought it might be mains frequency related but the frequency doesn't tie in, unless the scope is out of cal.

 

David

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sparrow2 wrote:

My guess is that you power don't handle the extra power when  the diodes open , very well

How good are the PSU, some good caps over GND and VCC near the 555 would probably help.

 


thanks I should consider that.I'll add cap.thanks

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its full circut in attachment.why this is happening? 

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Why is it happening - because you made it! What do you expect to happen? You created the circuit - surely you have some expectation of what you might want to achieve?

 

Why don't you use the simulator to show you current and voltage across the inductor and the capacitor? This might give you a better idea of what is happening. You have the tools at your fingertips - use them.

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Kartman wrote:

Why is it happening - because you made it! What do you expect to happen? You created the circuit - surely you have some expectation of what you might want to achieve?

 

Why don't you use the simulator to show you current and voltage across the inductor and the capacitor? This might give you a better idea of what is happening. You have the tools at your fingertips - use them.

which simulator u recommend?

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avr freaks forum is not working for me.nobody answer and just complaining

WELL I WANT TO KNOW WHY THIS CIRCUT IS WORKING LIKE THIS?

IF I CREAT A SQUARE WAVE WITH LTSPICE THE SQUARE WAVE WILL NOT FALL APART LIKE THIS?

I JUST WANT TO KNOW WHY WHEN I USE 555 AND HAVE A SERIE OF LC ON OUTPUT IT BECAME LIKE THIS

U DONT GET IT.DO U? 

NOW JUST COMPLAIN

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You should remember that this forum is not here just to solve your problems for you.  You will have to think about the problem and do some research.  Also shouting (UPPERCASE TEXT) will not win you any friends.

 

David 

 

 

 

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DAFlippers wrote:

You should remember that this forum is not here just to solve your problems for you.  You will have to think about the problem and do some research.  Also shouting (UPPERCASE TEXT) will not win you any friends.

 

David 

 

 

 

sorry

i get it now its because LTspice voltaj internal resistance of voltaj source of mine was zero . in 555 i should have buffer for output

 

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Over your dummy spit? Try using stack exchange and see what reception you get if you don't like the free service here.

 

What simulator do I recommend? How would I know?  I was brought up using pen and paper, simulators are novel to me. You mentioned LTSpice - if that works for you, use it. You've been using a simulator judging by your pictures. You only look at the voltage, the other part of the picture is in the current so set your simulator to show the current waveform as well.  Just don't ask me how to do it - I have NFI.

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Kartman wrote:

Over your dummy spit? Try using stack exchange and see what reception you get if you don't like the free service here.

 

What simulator do I recommend? How would I know?  I was brought up using pen and paper, simulators are novel to me. You mentioned LTSpice - if that works for you, use it. You've been using a simulator judging by your pictures. You only look at the voltage, the other part of the picture is in the current so set your simulator to show the current waveform as well.  Just don't ask me how to do it - I have NFI.

*unnecessary words removed. Moderator*

 

anyway thankyou all guys . i learned somthing in every post that u post

Last Edited: Sun. Jun 14, 2015 - 12:24 PM
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I think you're missing the point. I'm trying to give you the tools to answer your own questions. One day you might realise this.
Anyway, what you wrote makes no sense. I have no idea of what you're try to say.

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Kartman wrote:

I think you're missing the point. I'm trying to give you the tools to answer your own questions. One day you might realize this.
Anyway, what you wrote makes no sense. I have no idea of what you're try to say.

no need for that one day because right now i know that i asked a dummy question and by a little googling will be find out.

thanks for answering

my body here say that mr kartman is right and i should take lesson from him to not ask a dummy question again. lesson taken wink

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Did you even bother to look at the TWO AVR inductance meters I provided links to in Post #7 above?

 

Theirs works.

 

Yours doesn't.

 

One might want to spent a moment studying their approach, and comparing it to yours.

 

If you want to use an alternative technique, (there is more than one way to solve most problems), then you need to expect to spent a lot of time designing the circuit, and debugging it.

Analog design, especially with LC circuits, isn't trivial.

 

JC

 

 

 

 

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DocJC wrote:

Did you even bother to look at the TWO AVR inductance meters I provided links to in Post #7 above?

 

Theirs works.

 

Yours doesn't.

 

One might want to spent a moment studying their approach, and comparing it to yours.

 

If you want to use an alternative technique, (there is more than one way to solve most problems), then you need to expect to spent a lot of time designing the circuit, and debugging it.

Analog design, especially with LC circuits, isn't trivial.

 

JC

 

 

 

 

yes 

thankyou

 

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Navid

I warned you that such asking isn't wisely.
personally I think you got the best consultations here. nobody want to insult you or solve your homework. you cannot ask your pre-answered questions although all guys tried to suggest a better circuit or a source to introduce the fundamentals of L meters. you didn't even bother yourself to read them, did you?

and about Kartman and other friends here I have to say that he is like a father for me. I like all of the freaks.

 

also you shouldn't be disappointed for your problems. as Kartman said check out your circuit in simulation and tell them what's the problem. you think the problem is that the circuit doesn't make the output you expected but that's not the problem. that's your goal. the problem is what's going on there that you do not get the output you expected!? then simulate it and tell our friends what's going there.

 

Good luck

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

Last Edited: Mon. Jun 15, 2015 - 02:53 PM
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Rohalamin wrote:

Navid

I warned you that such asking isn't wisely.
personally I think you got the best consultations here. nobody want to insult you or solve your homework. you cannot ask your pre-answered questions although all guys tried to suggest a better circuit or a source to introduce the fundamentals of L meters. you didn't even bother yourself to read them, did you?

and about Kartman and other friends here I have to say that he is like a father for me. I like all of the freaks.

 

also you shouldn't be disappointed for your problems. as Kartman said check out your circuit in simulation and tell them what's the problem. you think the problem is that the circuit doesn't make the output you expected but that's not the problem. that's your goal. the problem is what's going on there that you do not get the output you expected!? then simulate it and tell our friends what's going there.

 

Good luck

yes you are right.and im sorry all guys.

i get that and solve my problem.

thanks 

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I haven't used a 555 since I started using avrs. But then, you can use a 555 in a 9v system without a regulator...

 

EEK! I lied! I made a coupler trigger for Larry 'cause he wanted a circuit he could build and "not any of your d*^m surface mount crap."

 

It's just easier to tell an avr how long I want the pulse to be than to find R and C of the right values. Especially since you can't go down to Radio Shack and get them any more.

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

Last Edited: Tue. Jun 16, 2015 - 01:04 PM
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Torby wrote:

I haven't used a 555 since I started using avrs. But then, you can use a 555 in a 9v system without a regulator...

in next measurment i will use microcontroller