Magnetic Control with Thyristor

[gravi]

Hi,

Could any one explain me what is happening in this circuit, This circuit is controlling an Vibrator with the help on magnetic coil, When Potentiometer "R7" is adjusted Vibration is increased or decreased proportional to the Potentiometer, but I couldn't understand what is controlling this Thyristor U2. I couldn't find any changes in wave form when Potentiometer is adjusted when tested in oscilloscope.

Thanking You,
Ravi Kumar G.

 

[FvM]

No circuit shown.

 

[gravi]

Hi,
could any one explain me the above mentioned circuit works

 

[FvM]

Q4010 is a triac, not a thyristor. I don't believe that the circuit works with a 1N4007 diode. I would expect a diac in this place which turns the circuit into a standard dimmer.

 

[gravi]

Hi,
According to the datasheet Q4010 is Thyristor and diac is built inside,




https://www.littelfuse.com/products...ttelfuse_Thyristor_QxxxxLTX_Datasheet.pdf.pdf


That circuit is working fine and tested but I couldn't understand the circuit functionality.

Thanking you,
Ravi Kumar G.

 

[FvM]

According to the datasheet Q4010 is Thyristor and diac is built inside

"Thyristor" is only written in the title line, quadrac (triac with built-in diac) is the exact specification. So the circuit can work. The 1N4007 has the effect that only negative halfwaves are triggering, so it's effectively a halfwave dimmer.

As any triac dimmer, the circuit performs (leading edge) phase angle control, the trigger time delay is controlled by the variable RC circuit.

 

[gravi]

Thank you FvM,
Yes my perception is wrong, Q4010 is an Triac with built in diac.

The circuit functionality is better explained in the following link

https://www.mikroe.com/old/books/keu/06.htm



So now the load is switched ON and OFF with some frequency is that true ?
Thanking You,
Ravi Kumar G

- - - Updated - - -

Thank you FvM,
Yes my perception is wrong, Q4010 is an Triac with built in diac.

The circuit functionality is better explained in the following link

http://www.mikroe.com/old/books/keu/06.htm



So now the load is switched ON and OFF with some frequency is that true ?
Thanking You,
Ravi Kumar G

 

[FvM]

Yes, the reference to the flasher circuit is interesting. With longer RC time constant, the circuit can produce pulses at lower frequency, e.g. 25 instead of 50 Hz. But for the given RC values (about 700k*22 nF = 15 ms) I assume that it's still generating cut 50 Hz halfwaves.