When this SCR is off, there is a Leakage voltage Current present

[ya20051123]

Found that there is leakage voltage, leakage current !!!!!!!
When the angle becomes smaller, it will happen.
Is it normal ???
What is the reason ??
How to improve??
Layout of the circuit

15° There is a clear leakage voltage

90°

150°

 

[D.A.(Tony)Stewart]

yes SCR's have leakage current. Normal? is what is the datasheet

 

[ya20051123]

Sorry for my first use ...
I want to express the place where the red mark is, why is there voltage and current?
No gate trigger, why is there a voltage and current.

 

[schmitt trigger]

With SCRs, I always put a 1k to 4.7k resistor between gate and cathode.

Are you measuring the "leakage" voltage across the 50 ohm load?

 

[ya20051123]

Yes, is the 50 resistance display.
I tested it.
There is no effect.
Why is it not equal to zero voltage?
Feel annoyed.........

 

[FvM]

It's unlikely that SCR leakage current would be constant independent of the applied AC voltage. I have no explanation at first sight, but I'm sure theat intelligent measurements can show the cause.

 

[mtwieg]

You show a +15V supply, is that supply rail common to the load ground?

Can you show a trace of the gate voltage along with the load voltage?

 

[D.A.(Tony)Stewart]

It appears you have poor signal capture skills and a signal to noise ratio near 0dB (when you can easily get 60 dB SNR or better) and an unspecified 0V reference leading to huge uncertainty on your source impedance during the OFF state and thus the power being transferred which ought to be about 50 uW.

If you are using grounded probe (disconnected) with a 50 Ohm resistor tied to Neutral and measuring current of the same resistor, you hardly need 2 probes to measure V & I for a linear load.

But you certainly need 2 probes to eliminate the common mode noise in your readings.

Try A-B mode with both probes on Neutral then Line then Load and ensure you get a FLAT LINE before submitting another picture, or a better question. ( ensure probe gnd goes to earth gnd not neutral)

You probably have Neutral shift from a Bridge load somewhere contributing to major ground shift measurement errors.

REmember Earth ground is 0V by definition at earth and not your probe and not your resistor and not your power outlet.

Capture with 0V on your probe must be your reference point and not some remote ground tied to Neutral and thus neutral noise added to your results. ( easy to find an HP Power Supply Manual which shows how to measure supply noise with probes from mid 60's)

next time show measurement method.

Go read an HP power supply manual from 1967 off the web and learn how to use a scope. Then you will know how to use probes.

 

[ya20051123]

gate voltage = blue

 

[ya20051123]

I'm sorry I'm a student.
Too much detail will not be, so I show my measurement results.
Each end is an isolated probe.
See your advice, I thought, I was not wrong mode. So I switched the mode to DC coupling.
haha...........(I am an idiot........