# Can anyone explain me this circuit

• gaurav_dua
It has an open collector output that can be used for pulses or square waves, but it is not meant to be used with a battery.f

#### gaurav_dua

http://prntscr.com/60xcwx

Thank you

This is a homework exercise?

It should be in the homework subforum.

This is a homework exercise?

It should be in the homework subforum.
no, this is my project for school

What is the circuit supposed to do?

Seems a bit odd. If you connect the battery when there is no light on the LDR, the thyristor will turn on, the LED will start glowing and there will be a click in the speaker. When the LDR gets illuminated - it depends on the thyristor and the speaker (a thyristor will not turn off if the load current is large enough).

What is the circuit supposed to do?
this is the circuit of a laser security system

Seems a bit odd. If you connect the battery when there is no light on the LDR, the thyristor will turn on, the LED will start glowing and there will be a click in the speaker. When the LDR gets illuminated - it depends on the thyristor and the speaker (a thyristor will not turn off if the load current is large enough).
Can you explain in more detail?
Thanks

Can you explain in more detail?
Thanks

From http://en.wikipedia.org/wiki/Thyristor :
Thyristors have three states:

1. Reverse blocking mode — Voltage is applied in the direction that would be blocked by a diode
2. Forward blocking mode — Voltage is applied in the direction that would cause a diode to conduct, but the thyristor has not been triggered into conduction
3. Forward conducting mode — The thyristor has been triggered into conduction and will remain conducting until the forward current drops below a threshold value known as the "holding current"

zoki85
Another thing I would like to add is the thyristor is BT-169

What can you tell us about the Speaker?

Have you bought the components? How does the laser get used?

Another thing I would like to add is the thyristor is BT-169

Look at http://www.nxp.com/documents/data_sheet/BT169_SER.pdf [Broken]

A slight problem: BT-169 is not specified for DC operation.

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