Understanding the following scheme (audio amplifier with IR2153)

Thread Starter

Motanache

Joined Mar 2, 2015
540
IR2153 has a fixed duty cycle.
Ton and Toff depend on the duration of charging/discharging of the condenser Ct through the resistor Rt (R4 and C1).

However, the potential of pin 3 should not get too close to GND, because IR2153 shut down.

If in pin 3 it brings positive potential via C7, Ct(C1) will charging faster than it discharging.
Therefore, DT is no longer 50%.

Q1 is a transistor that works the common base. I do not understand why.
(Its base is put at the GND for alternating current through 220uF)
 

Thread Starter

Motanache

Joined Mar 2, 2015
540
This is an unconventional use of IR2153.
RT is R4 in the schematic.
The datasheet uses RT or Rt.

Charging/discharging of the condenser CT(C1) is through the resistor RT (R4).

In parallel with RT(R4) I intend to put a photoresistor with the diode in series.
This changes the CT(C1) charging time.

Thus duty cycle varies depending on the photoresist illumination.

The modulation signal will be audio.
I'm trying to get some kind of Constant Off Time PWM.

I have only one IR2153. If I break it ...


A schematic would clarify.
But I do not know how to use IR2153 or TL494 in LTSpice.
To start with a simulation would be a good idea not to burn the integrates.


I could post the simulation in LT Spice if you help me to use IR2153 in LT Spice
 

Thread Starter

Motanache

Joined Mar 2, 2015
540
Thank you very much!

Now I have to learn how to add a new library or a new model in LTSpice.
I am very beginner with LTSpice, but I've already worked on simulation programs.
 

Thread Starter

Motanache

Joined Mar 2, 2015
540
I copied all these files into a single folder. I opened with LTSpice the .ASC file.

It has worked!

He gave me a error not knowing the IRF840. But I have replaced with IRFZ44 and worked.
 

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Thread Starter

Motanache

Joined Mar 2, 2015
540
... and here's a TL494 model:
Can you please give me an example of .ASC file with TL494 ?
I do not know how to add this component in the LTSpice schematic.

I tried to introduce in that branch an optocoupler (CNY17).
I thought he(CNY17) would control duty cycle of IR2153 depending on the input signal(in CNY17).
Even in the simulation does not work:
 

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Thread Starter

Motanache

Joined Mar 2, 2015
540
I tested IR2153 after the scheme in # 6 (.ASC file).

Instead of the signal generator from the schematic, I put the music, a signal with the amplitude of a few volts.
I know it should have a signal with a much higher amplitude.

It sounded a little bad it seemed to me. I quit this idea for the moment.

As a tip, if you test this schematic, Have a capacitor in series with the speacker.
I have often mistaken I put DC in the loudspeaker.(few mVs are normal)

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About LTSpice
Can the signal generator be replaced with music?

I worked in Proteus and there it was possible. Instead of the signal generator, you could put an audio file and record the output signal to another file.
But in Proteus I can not simulate IR2153.
http://appliedelectronicsengineering.blogspot.ro/2015/08/testing-real-audio-signal-with.html
 
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