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555 timer output set to 200hz is not what i was expecting to see?

Tonymura

Jul 25, 2021
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Hello everyone.

How are we all going

My very first post here and hopefully i have put this question in the correct thread. So please be niceto me.

Just a simple question to ask you all anyone or someone who might be more familiar with the 555 timer ic.

About a week ago i put together a simple circuit using the old famous 555 timer in a bid to get an output frequency of 200hz approximately is near enough for what i require but after completing this small circuit i decided i would view the signal with my oscilloscope but to my surprise what i was seeing was in fact a very distorted and very weak signal coming out, if i could call it a signal or for that matter a waveform at all? really nothing that i did look anywhere near of what i had expected at the output of pin 3 from the ic

At first i thought i had blown the 555 timer up but changed it with another but still no output waveform. I played around using different types of electrolytic capacitorsand resistors but, still no such luck. I even went as far as testing the scope thinking something was wrong it but it works just fine even though i haven’t been using it for many many years.

Just wanting some advice from someone to explain to me what i am doing wrong and why as I cant see a clear square wave signal. ( oops i need to post the curcuit, please wait i will soon )
Im definalty doing something wrong here.

Thank you in advance.
 

bertus

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Nov 8, 2019
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Hello,

If you post a schematic, keep the size at max 300 kB.
Did you made the circuit by yourself or from an other source?

Bertus
 

Tonymura

Jul 25, 2021
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Hi Bertus
Nice to meet you.
wow so quick to reply. Thank you so much
Here is my curcuit i went to a website that works out the calculations for you. ( its called Ohms Law Calculator and choose the 555 timer ic program to do the thinking for me )
The frequency is about 182hz near enough for what i wanted to do.but got nothing near what i was expecting to see from my scope.555 timer circuit.png
 

Tonymura

Jul 25, 2021
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Hi again

oh i see

opps my fault omg i did do something majorly wrong

looking at this now i think the value of the capacitor i inputted before just 47 and even used a 33 value, and this would give me and output reading of 0.201 when i should have put just a .033uf in the parameters

i am a little bit out of touch sorry about all of this i think i ought to go back to basics.

Ill try the values you put up and see what i get on the scope.

I am sure you are correct. My fault...

Thank you once again ill keep you posted and show you my final image on my scope.

I feel so silly.

Thank you once again.
 

bertus

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Nov 8, 2019
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Hello,

An other question. Wich version of the 555 are you using?
A bipolair version (NE555 / SE555) or a cmos version (LMC555 / ICM555).
The specifications are quite different.
Have a look at the attached datasheets.

Bertus
 

Attachments

  • NE555_sgs.pdf
    141 KB · Views: 1
  • NE555_texas.pdf
    707.9 KB · Views: 0
  • ne555_TI.pdf
    569.8 KB · Views: 0
  • icm7555-56.pdf
    499 KB · Views: 0
  • lmc555.pdf
    767.1 KB · Views: 0

Tonymura

Jul 25, 2021
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Thanks Bertus
i have approxamatly about 30 off these 555 timers
The brand are all Philips NE555N J74818K Jnr132P
They are very old.
So which one would that be and can they be used for the circuit that i built?
 

bertus

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Hello,

Those are the bipolair type.
What supply voltage do you use?
The bipolair starts working at 5 Volts and will work upto 15 Volts.

Bertus
 

Tonymura

Jul 25, 2021
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.
I use a voltage between 9 to 12 volts dc to answer your question.

You might be wondering exactly what or why i am building this circuit for and for what purpose i am using it.

This circuit i am trying to build is for a supply rail for one of my car solenoids a pressure regulated located inside my cars automatic transmission. The brand is a Bosch.

This solenoid in question is for my Ford Falcon BF and requires a PWM of about 200hz voltages power supply between 10.5 when battery is low and 12.7 when fully charged so i am trying to test to see if it will open and close correctly without damaging the unit.

If i damage it…..i will be out of pocket for about a $200 for a genuine unit. ( so failure is not an option )

The other solenoid can be tested with direct 12 dc but this so called an S5 solenoid requires this sort of power requirements.

I am planning to use a driver a MOSFET BUZ90A within the cuircuit that will be the workhorse from pin 3 output to the gate of the power transistor and hoping to design something that will suit this solenoid.
 

bertus

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Hello,

You can do better than a BUZ90A.
An IRL540 will out perform the BUZ90.
BUZ90A_electrical.png


IRL540_electrical.png

The breakdown voltage of the IRL is much lower, but do you really need 600 Volts?

Bertus
 

Attachments

  • BUZ90A.pdf
    179.3 KB · Views: 0
  • irl540n.pdf
    135 KB · Views: 0

Tonymura

Jul 25, 2021
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Hi mate

This was the first semiconductor that i took out from my pile of collection.

I have quite a lot but thought i would just use a higher rating to better protect my project that I am doing just to be on the safer side

I could go searching for the one that you mention but this would take me hours if not day with the amount of units that i have at hand so....i would prefer not too.... unless you think otherwise that this this devise isn’t a good option.

Having said.....so oh yes....you are correct...i do have a rl540n somewhere...yes i seen it but... somewhere in my cardboard box of collection but prefer to just use the unit i have at hand now as this would take me sometime finding it.

Please advise me if you disagree.


.
 

Audioguru

Sep 24, 2016
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Tony, did you notice that the value of your resistors are 1400 times too small and the value of your capacitor is 1400 times too large?
 

Tonymura

Jul 25, 2021
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Hi Audioguru
what i noticed was that i just didnt input any correct figures or values...decimal placing were all wrong
Which explains why i couldnt see anything on my scope

what Bertus explained and picked up in this post was that my........"resistors are to low in value"
 
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