PWM to AC Signal. The signal never across the secondary side. Pls help!

[betwixt]

... could equally be part of an echo sounder, an ultrasonic cleaner or a bird scarer. Over to you Mehmet....!

Brian.

 

[mvliege]

Dear Brain,

I have changed my project. I used DC-DC converter (ST 34063- step down with external PNP switch). I have achieved to see signal secondary side but not AC. I saw around 400V DC with my multimeter but I have never seen AC value.

Could you give me some filter to get around 80Hz?

I have added two picture with secondary side and primery side.



All the best,
Mehmet

 

[FvM]

DC across C5 is in fact expectable, because it's the output filter of a rectifier. Where do you specifically expect AC voltage and which waveform?

Some design details are mysterious, e.g. the purpose of L1. What's the transformer windings ratio, what's the expected voltage at C16/C17 and the intended purpose of the feedback path?

 

[mvliege]

As shown on the figure below,
"Sender" output should be around 130rms/80Hz. I have tried frequency modulation with PWM to get sine wave but I couldn't

In the below picture I have also added my exact project

For my circuit,
Transfer ratin raito 1:15
L1,C16 and C17 for modulation

When I finish my project I'll put here its whole circuit to checking.


my exact ptoject;


thank you,
Mehmet

 

[betwixt]

So basically you are detecting whether something touches the resonator by seeing if it's resonance is being damped.

I've never worked on anything using that method although it seems perfectly reasonable. Why use such high power though, making the resonator part of the tuned circuit would make it far more sensitive and not require anywhere near us much power.

Brian.

 

[mvliege]

Dear Brain,

Could you please give me some advise about electronic for beginner level?
I think it is the best to make more practices to gain more experience.
And you can also give me some electronics magazine, website that it should be include lots of circuit example.

I'd like thank you in advance for your value assistance.

All the best,
Mehmet

 

[betwixt]

I think the project you chose was not the best for learning electronics! To be honest, Edaboard is very good for learning and I do not know of any web sites or magazines that cater for beginners. There are lots of references to specific topics on the internet but maybe nothing that is a complete tutorial. It is a very big subject!

For your project, you do not need high drive voltages, in fact very low voltages would work better so all the transformer and driving circuits are unnecessary. The way to do it is to drive the resonator through a high impedance so it is easily influenced by anything touching it. You have to use the natural resonant frequency for best results, that depends on the resonator itself but is usually in the KHz region rather than 80Hz.

Brian.

 

[mvliege]

Dear Brain,

Thank you so much, I really appreciated.

I have to do more practice. I have many BC547 in my hand. I just want to know how to use this transistor's datasheet.
What is meaning of Vceo, Vcbo, Vc(sat), Vbe(sat)? If I can find out how to use these parameters, I think I will know all how to calculate exact resistor value.

I can't how to thank you. I'm sorry If I disturb you.
I just really learn to electronic as soon as possible.

All the best,
Mehmet

 

[Audioguru]

You need to learn the basics of electronics maybe from a book like The Art Of Electronics that is available on the web.

When Vceo is listed on the datasheet for every transistor under the topic called Maximum Ratings then what do you think it is about?
It is the maximum allowed Voltage between the collector and emitter when the base is open (not connected to anything).

Vcbo is the maximum allowed voltage between the .... and the .... when the .... is not connected to anything.

Vc(sat) is the maximum voltage from collector to emitter at a certain current when the transistor is saturated (turned on hard).

Vbe(sat) is the maximum voltage between the .... and the .... when the transistor is saturated.

Some transistors have maximum ratings but others are a little better. Some ratings are listed as minimum, typical and maximum so you might design a circuit using each one to see how much the different transistors perform.