Dielectric absorption. The dieelctric material will tend to trap some small portion of the electrons in an electrolytic capacitor at it's fully charged state within the dielectric material itself. When discharged abruptly and disconnected (electrically) from the circuit it will gradually leak those charge carriers back onto the plates of the capacitor so it will gain some voltage.

 

AG, they're just covering their bases, cross posting on the SAME site is different the users are the same and all users on that site have the ability to read the posts in each catagory of the forum, cross posting is rude in that case. Asking the same question on multiple different sites is perfectly acceptable, this site has a different user base than that other site.

 

Asking the same question on multiple different sites is perfectly acceptable, this site has a different user base than that other site.

I guess you never heard about WALTERS who posted the same simple and odd questions on many sites, maybe here. He was banned on many of the sites.
Somebody recently asked if RRITESH is WALTERS coming back again.

RRITESH also posts the same questions on many sites, not just two.

 

Sorry AG, I treat every poster as a human being using only the content of the post as a basis for the answer, it's probably a personality flaw of mine, haven't been able to ditch it. I also don't so closely track multiple sites that I would even notice something like that. I have only a few hours a day on a good day on the various forums I frequent at the best. I often go weeks in between sessions when I can observe and post frequently, so I have to approach every post on a thread as if it were an honest question, I don't don't spend so much time here that I can correlate it all.

 

I have Digital multimeter which can't measure ac current, as i was making rectifier from 18-19V transformer, soldering Diode and capacitor it gives 25-26V this dc current i can measure with D.multimeter it show's near by 7amp.

pls tell how to find ac current given by transformer.

 

I have Digital multimeter which can't measure ac current, as i was making rectifier from 18-19V transformer, soldering Diode and capacitor it gives 25-26V this dc current i can measure with D.multimeter it show's near by 7amp.

pls tell how to find ac current given by transformer.

You can measure AC current using the AC voltage range on your multimeter, and using an appropriate shunt resistor. At 7 amps you might want to consider a 10 milliohm shunt resistor. You can also use an AC current clamp which produces an AC voltage in proportion to the current flowing.

 

Neutrinos is the way to go.....I recently noticed that if oscillation of such animals can be accomplished at 60Hz than you have it made. Proprietary information....

 

I have Digital multimeter which can't measure ac current, as i was making rectifier from 18-19V transformer, soldering Diode and capacitor it gives 25-26V this dc current i can measure with D.multimeter it show's near by 7amp.

pls tell how to find ac current given by transformer.

Here we go again, you need to understand ohm's law. You can't tell how much output a transformer is capable of by hooking an ammeter across its output - rectified or not.

 

In ltspice software, to make transformer circuit it ask how much impedance of sec. and primary coil , pls tell relation between no. of turn's and impedance.

 

Transformer modeling in spice isn't that simple, you can do mutual inductance but it won't act like a real transformer, try the LTSpice user group on Yahoo groups they have an incredible LTSpice group that has a lot of really good models including heavily fleshed out transformer models. Keep in mind getting the values of a real world transformer to plug into spice is not particularly easy.

If you're knew to all of this give up the idea of simulating a transformer from the start it's going to be massively over your head.

 

In ltspice software, to make transformer circuit it ask how much impedance of sec. and primary coil , pls tell relation between no. of turn's and impedance.

Yes, because LTSpice is a design program and it expects you to have data sheets on the devices you're designing something with.

As to inductors and transformers - due to core material, wire diameters, methods of winding etc. it's impossible to make any correlation between the number of turns of wire and the impedance it will present at a specific frequency.

For simple air wound coils used in RF circuits yes, but not in this case.

 

ok, i also want 555 and other ic to design in LT spice software where to add this ic's as they are not present in it.

 

There are 555 models for LTspice, you're not looking for yourself you're asking here.

 

I have seen 555 ic model but, it was internal circuit and i also want more ic in it.

 

Not to to be offensive, but if you looked you didn't look well enough.
lib/sym/Misc/NE555.asy contains the symbol
lib/sym/sub/NE555.sub contains the subcircuit model
These can be added using the standard F2 button and going to the Misc directory.

I could however be mistaken and I may have installed this model myself and forgotten, if that's the case I've attached the asy and sub files simply place them in the appropriate directories and you'll be able to use it.

Keep in mind this is a 555 behavioral model, and won't properly mimick all the possible quirks of a 555 circuit under odd conditions, this is what the full transistor models are for.

 

I was making inverter for this i have taken output from 555 ic with darlington in common collector mode, i tested different frequency and when connected the output to secoundary of transformer it was showing 8v in one transformer and in another it show's zero , pls tell procedure and mistake i have done in this circuit as i have tested the output of 555 ic with multimeter.

the transformer were of 18v and 14v RMS.

 

I answered this question 10 seconds ago on another website!
You are feeding DC pulses into a power transformer that is designed for an AC sine-wave.

 

i am making 555 ic inverter for this, i have circuit but the problem is that when output is taken from Mosfet or Darlington the transformer gives less than 40v, if i change frequency of ic the output is same.
the transformer used for this is simple 220v to 16v..!

 

Please do not make many threads about the same simple circuit.

You show a 2N3055 junction transistor which is not a darlington and it is not a Mosfet so its output current is much too low for an inverter.
The 25V supply far exceeds the max allowed supply voltage rating of a 555 timer IC.
Look at my reply to your other thread about this circuit.

 

You're feeding 7 Hz with a duty cycle of 75% into a transformer of unknown origin.

You also mised the 0.01 uF bypass capacitor for pin 5 of the 555.