Laser question

That is a bare laser LED and needs something approximating a constant current driver and a DC supply applied the right way round. I expect laser diodes to be more tetchy than LEDs about reverse voltages too.

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Regards, 
Martin Brown
Reply to
Martin Brown
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What do you think of this?

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It has the driver. Should be all I need except for power source.

Andy

Reply to
AK

That device doesn't have either the specs or the description you posted. You made a mistake, we all do.

Cheers

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Clive
Reply to
Clive Arthur

The LM317 current source will work, but the dropout voltage is better if you use a TLV431 and NPN transistor for low-side current limiter.

Reply to
whit3rd

Well as others have said upstream, the simplest current source is a voltage source and the right resistor. I think you should start there. Do you have a DMM voltmeter? Get a 12V (or other) wall wart, and calculate how big a resistor you need, say start at 5mA and work your way to 30-40 mA. You can assume the laser diode voltage stays constant with current. (As a first approx., you can set the diode voltage equal to zero, with V>12 V.)

George H.

Reply to
George Herold

Thanks.

I have both DMM and RMS meters.

I decided to order 2 laser diode with a builtin Red Dot Module Diode driver.

The detector and other components of the laser alarm project uses

LDR (Light Dependant Diode) L.E.D (Light Emitting Diode) BC547 Transistor (1)

100 ohm or 330 ohm resistor (1) Buzzer (1) 9v Battery with holder
Reply to
AK

said upstream, the simplest current source is a

That sounds like it should get you started. You can use led's to test your circuits.. Cheaper than laser diodes. 30 - 50 mA may let the 'magic smoke' out of some but lower currents should be OK.

George H.

Reply to
George Herold

I did some experimenting with the resistance of the photo cell.

Photocell 400mW 350V pack 8K ohm Max Light 1M ohm in. Dark

At about 6 inches from the laser, it's about 165 ohms.

At 18 feet, it is around 160 ohms. (I turned on a 60 watt light, but it did not appreciably change the resistance.)

In darkness, it is about 24,600 ohms.

Reply to
AK

ere.

.

driver.

tance.)

I got my NE 555P chip in. I need some help.

How do I hook up my switch as shown in this diagram?

To turn off the alarm and reset the system, a (single pole double throw) switch disconnects the speaker and sends the LOW signal from the output pin 3 to the trigger pin 2. The system is now deactivated. To reactivate it, f lip the switch back to the original position. The alarm will remain off unt il the next time that the light beam is interrupted.

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Reply to
AK

there.

mA.

t.

e driver.

istance.)

) switch disconnects the speaker and sends the LOW signal from the output p in 3 to the trigger pin 2. The system is now deactivated. To reactivate it, flip the switch back to the original position. The alarm will remain off u ntil the next time that the light beam is interrupted.

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Looks like I need a 8 Pin DIP IC Socket Adaptor Solder Type.

Is this the kind of board I need?

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Reply to
AK

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