Hello Reader,

I am Planning on Making a circuit in which a laser is attached to a switch and AC Adapter.

The Laser module that i am using is:

- Red Laser Module - Focusable Dot (3.5V~4.5V 16mm 5mW)

I am don't know what suitable AC adapter should be used so that it won't cause the laser to blow up and still achieve a bright laser light.

Any help would be great full.

Cheers

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The first thing you will need is a circuit called a "constant current circuit" so that the laser diode can be connected to almost any power supply.

Next you will need to know the current requirement of the laser diode.

 

what is this constant current circuit, and how can i make one?

 

You can use an adapter with 4V DC output and current rating more than 2mA (if you want to connect only one laser module). I think even the smallest one available in the market will have a higher current rating.

 

Cheers premkumar. I hope this works.

 

You can use a LM317 voltage regulator to deliver a constant current as shown in the following circuit:

http://www.talkingelectronics.com/pr...antCurrent.gif

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Perhaps it is not the power supply but the circuit design that matters. the diodes, whether laser, UV, IR, or visible are current devices and call for current limiting in form of either resistor in series, constant current source or PWM methods.
thus searching for smallest adopter doesn't appear logical,but for economics. The device can be made to work even from a vehicle battery.

__________________
Regards,
Sarma.

 

The diagram shows a module which requires 3.5 to 4.5 V and the power consumption is given as 5mW. So if you are connecting a voltage source with 4V and current rating of more than 2mA, then the device will take the required current only . Otherwise if you have a different voltage source, say 12V, then we have to use a regulating method which has to limit the current to the specified value.

 

generally these devices are connected to 3*1.2V ni-cad cells that provides 3.6V supply. we cant even use 2 dry cells as the voltages falls below3.5.
there are no standard supplies at 4V other than 2 nos of lead acid cells.three ordinary cells , though high at the begining might work. but as somew one might try duracell type ,the voltage is more and would not fall for some time , thus might cause damage. So i suggested some series resistor like 5 to 10ohms.

__________________
Regards,
Sarma.

 

The OP asked about the AC adapter requirements. So I tried to give a straight answer with out confusing him. If 4V is not available, then I would have suggested some method to regulate the current. Also here the the device is taking only 5mW. So the current will be less than 2 mA. To drop 0.5V at this current, the series resistance has to be 0.5/2 = 250Ω. A 10Ω resistance will drop only 20mV . Am I right?

 

Isn't the '5 mW', the light output of the laser, not the power requirement of the diode? I'll search later, but think its more in the 30 mA range.

Sam's Laser FAQ - Preface, Introduction, What is a Laser?, Safety

Pretty much everything you'll want to know about Lasers...

 

You may be right. I thought the power consumption of the module is 5mW only. I am not familiar with this device.

 

Does anyone have a recommended idea of what Adapter i should use?
I was considering the 4V AC adapter idea given by premkumar9. But are there any others that i should take into consideration?

 

Read through the Sam's site, lots of good information. You should try and find a data sheet for your module, might already have some circuitry built in, which might complicate your plans. You need to be very sure about your module, as you probably won't get a second chance if you make a mistake.

 

I heard of laser modules that you just supply a voltage to as they have the current limiting resistor built in. This might be one of those, or it mightn't and could burn. Is there a datasheet?