CR123A housing HAS blue ray.

[Archane]

Re: CR123A housing awaits blue ray.

Rog you could use aluminum instead of stainless, I mean yeah steel would be awesome to have but not required.

I've been thinking of getting something like that machined out but I need to sit down and draw it out, and well, I can't draw diagrams for sh!t. I try and fail =)

 

[rog8811]

Re: CR123A housing awaits blue ray.

At the end of the day, with this experimental stuff, the type of metal to use is the type you find

I am now glad I put this thread up before I built the circuit, as usual the forum members have come up with a good solution, all parts are now on order. It will delay the build but it will be worth the wait

Regards rog8811

*Edit....If I read it right this will be my circuit, I show only a pot (value???) as I am not sure I could shoehorn another resistor into the space.

 

[Gazoo]

Re: CR123A housing awaits blue ray.

Rog,
I believe the LD is supposed to be connected to the output and not the common side. I am going to have to check this out. Just be careful when you adjust the current... But it is sweet and simple...it's all we need for this.

The only other component I am going to add is a .33 Tantalum capacitor across the input. I believe it is used to prevent transient spikes from reaching the regulator, but is really only necessary if the regulator is a distance ( don't recall off hand) from the power supply.

I powered my blu-ray from using an LM317 last night and it is beautiful! I couldn't wait for the other parts I have ordered...lol...everyone that has ordered one will love it..

I forgot to mention you might want to put a 1 ohm resistor in series with your diode to get the current reading. Measuring the voltage across the resistor will be the same as if you used your meter to measure current, and I believe it is more accurate. This is optional but I find it so much easier.

 

[Gazoo]

Re: CR123A housing awaits blue ray.

I had an old 7805 regulator I tried and no matter how I hooked it up, the current to the load increased with voltage input. It is possible the regulator is bad because it has been used before and it was years ago. But if this is how it is going to behave, then we would be better off using the 78L05A as a voltage regulator and using the trim pot to regulate the current going to the diode. I won't know for sure until I receive my parts. Hopefully someone else will step in here and shed some light on this.

 

[zerafiel]

Re: CR123A housing awaits blue ray.

Nice body. Very sleek. I want one too. Looks better than the torch I was going to use.

I am going to go with the lm78L05 current regulator circuit in the spec sheet as well. So I am assuming the Vout reference is a fixed 5V (4.75-5.25) so to get 40mA I'd need 125ohm.

Would a this 200ohm trimpot have sufficient precision? Seems like a resolution of 20ohm
http://cgi.ebay.com/BOURNS-Series-3...9762338QQihZ002QQcategoryZ58164QQcmdZViewItem
Or can someone recommend a good one to use that's not too big.

As for the input capacitor, I am assuming I need a low esr ceramic 0.33uF ?V or would some other capacitor work as well? Output cap would be a 47uf 10v tantalum or electrolytic.

Let me know if there is any problem with this setup since I know nuts about capacitor selection.

 

[rog8811]

Re: CR123A housing awaits blue ray.

So I am assuming the Vout reference is a fixed 5V (4.75-5.25) so to get 40mA I'd need 125ohm.

That is the way I understood it xarylx. I am looking for a multiturn to suit as well.....

@Gazoo I lifted the first part of the circuit straight out of the spec sheet you kindly posted...... I am now hoping that your bits arrive soon so that you have the answers before I can build mine . As for the tant, the input leg of my reg will connect directly to the positive contact pad for the battery so with luck it won't be needed.

 

[catdog]

Re: CR123A housing awaits blue ray.

I cant say I have ever seen a 7805 used as a current regulator before - with the simple reason being that the lm317 does a better job I guess:

Voltage across bluray diode: 4.5-5.5V
Voltage drop across 7805: 1.7V
Voltage drop across resistor: 5V
---------------------------------------------
Total input voltage required: 11.2-12.2V

You will therefore need a 12V battery to get this circuit to work. You would be much better using the 7805 as a voltage regulator, and putting a (adjustable) resistor in series with the diode to limit the current as mentioned earlier.

 

[zerafiel]

Re: CR123A housing awaits blue ray.

So you are saying the lm78L05 has no reference voltage and there will be a voltage drop of 5v across the resistor if used as a current regulator? So it won't work with 7.2V? If so, it won't work with 12v either since it puts out a fixed 5v before the trimmer anyway. I had the impression it would put out 5v AND regulate the current but the resistor seems to be on the wrong side.

But with 5v and a series trimmer, the diode will see less than 5v. Around what value of resistance would be good to aim for to hit 40mA? 10-15ohm?

 

[rog8811]

Re: CR123A housing awaits blue ray.

I have been looking at the data sheet and not finding details (other than the diagram) of how it works as a constant current source......

@gazoo, in your experiment yesterday If you set the input voltage could you adjust the current without the voltage changing....also did you try wiring it as per the diagram ( I know you had doubts about it)?

Regards rog8811

 

[rubberband]

Re: CR123A housing awaits blue ray.

would deadles circut work for one of these diodes?

i already made one with a lm317 to-92 package and i was wondering if this would suit the blu-ray diode

 

[rog8811]

Re: CR123A housing awaits blue ray.

@rubberband, if you look at the LM317 thread there is a lot of discussion about using it with the blue...the answer seems to be yes if driven by a 9v battery.

The issue here is that some people (me) want to use 2 X RCR123 batteries (7.2v) to get a smaller overall package size.

Regards rog8811

 

[rubberband]

Re: CR123A housing awaits blue ray.

oh i see

sorry i didn't read the thred fully :-[
that case you built looks really nice . i have a wickedlasers sonar case so i can't wait to find what you come up so i can use it in the sonar case.

thank you,
Mitch

 

[rog8811]

Re: CR123A housing awaits blue ray.

I don't know the sonar, what batteries does it take?

 

[Gazoo]

Re: CR123A housing awaits blue ray.

Hi Rog,
Yes, I did try it both ways...as I said my regulator could be bad. I assure you just as soon as my parts arrive I will try again with the new regulator. I made an error by ordering the 50ohm trim pots....what was I thinking.. : Fortunately I can still use them by placing a resistor in series to get the correct value.

Maybe catdog is on to something...his explanation does seem reasonable and might explain why mine would not regulate properly. If we can't use these as current regulators, I would have no problem using them as voltage regulators. Running mine at 40ma's, it is putting 4.9 volts to the diode using the LM317.

I am sorry about all of this confusion. I did PM Daedal and he confirmed the regulator would work as a current regulator, and I did explain to him I intended to use a 9 volt battery before I suggested using it.

 

[catdog]

Re: CR123A housing awaits blue ray.

So you are saying the lm78L05 has no reference voltage and there will be a voltage drop of 5v across the resistor if used as a current regulator? So it won't work with 7.2V?

In the 7805 current regulator configuration shown above, the circuit will operate exactly the same as a 317 however the reference voltage will be increased from 1.25V to 5V.  This is a bad thing as it requires an additional 3.75V from the batteries.  So no, this circuit will not work from 7.2V

If so, it won't work with 12v either since it puts out a fixed 5v before the trimmer anyway. I had the impression it would put out 5v AND regulate the current but the resistor seems to be on the wrong side.

The regulator will maintain 5V between its output pin and the common pin.   In the configuration above, the common pin is floating, so can be at any voltage.  This means that the voltage to the laser diode can also change (which it must do to be a current regulator).

If you connect the common pin to ground, then the output will be 5V.

But with 5v and a series trimmer, the diode will see less than 5v. Around what value of resistance would be good to aim for to hit 40mA? 10-15ohm?

You are correct here - the bluray diode will probably operate, but it may not be possible to achieve full output power from 5V.

In short, these voltage regulators are not really suitable for this application.

 

[Gazoo]

Re: CR123A housing awaits blue ray.

catdog, Thank you. I am pondering ditching the 7805 idea entirely and reverting back to using the 317. I suggest we all do the same and I once again apologize. This was probably a bad idea and I should have tried it before posting about it.. :'(
Lesson learned.