BLuRay mod #2. 1xAA boost circuit.

[IgorT]

Hi chimo!

Since this is a step up circuit, what about the current ripple?

My LM3410 circuit seems to work great, but even tho the red LDs are much sturdier than a blue ray, i'm worried about them.. I built an LC filter just in case... Basically, i have two 47uF tantalums on the circuit output (for the switch on spike), 10uH chokes on the + and the - pole and two ceramic SMD caps directly on the LD, a 1uF and another with more than 20uF (for high frequency ripple)..


I know from experience how much more sensitive the blue rays are, so how did you protect them from this?

Do you think my filter should be sufficient for a red or even a blue ray?

 

[chimo]

IIRC, in the testing phase I hooked it up on the scope. The ripple didn't look to be a concern. Since LDs are normally pulsed (at least the writing ones), I didn't consider the ripple to be a large factor.

Just checked the data sheet and threw another un-modded charge 2 go unit on the scope with 100, 150 and 470 ohms dummy loads. The loaded ripple voltage was less than 20mV (pretty good). The unloaded ripple voltage was around 200mV.

The max current through the loads was about 38mA and the lowest was 12mA. I solder a small 1uF ceramic cap between the legs of my LDs. In general, you want to use a smaller cap for higher ripple freqs. A cap with a low ESR will be faster to respond.

Paul

Hi chimo!

Since this is a step up circuit, what about the current ripple?

My LM3410 circuit seems to work great, but even tho the red LDs are much sturdier than a blue ray, i'm worried about them.. I built an LC filter just in case... Basically, i have two 47uF tantalums on the circuit output (for the switch on spike), 10uH chokes on the + and the - pole and two ceramic SMD caps directly on the LD, a 1uF and another with more than 20uF (for high frequency ripple)..


I know from experience how much more sensitive the blue rays are, so how did you protect them from this?

Do you think my filter should be sufficient for a red or even a blue ray?

 

[IgorT]

The max current through the loads was about 38mA and the lowest was 12mA.  I solder a small 1uF ceramic cap between the legs of my LDs.  In general, you want to use a smaller cap for higher ripple freqs.  A cap with a low ESR will be faster to respond.

That's why i have two.. A 1uF and another larger one in parallel directly on the LD.. My engineer said ESR drops if more are soldered in parallel.
Should this be fine? If smaller ones are better, i can put several of 1uF in parallel.


On the other hand, i was thinking about the same thing - the LDs being pulsed for writing anyway.. So maybe this ripple doesn't really matter all that much. Thanks for bringing it up.. I was trying to find something about it in Sam's FAQ, and couldn't.. But now i feel much more confident about the safety of my LDs.


Well, i'm putting it all together tomorow and i'll have the ripple measured at work next week.
If it was suitable for Blue Rays as well, that would be great! I would love having the possibility of powering a BR from only two Ni-MHs or a single Li-Po...

 

[IgorT]

Since we don't know yet, if the cheap DX versions of Charge2Go are also suitable for this, i ordred all three versions, they have available..


Even if they don't work for lasers, they will come in handy for something else.. Besides, just the components are worth more, than what they cost, if i were to buy them here...


The chargers started packaging today, which means i'll have them here before the end of next week.. After i test them, i will post the results.

 

[chimo]

Good stuff!

Since we don't know yet, if the cheap DX versions of Charge2Go are also suitable for this, i ordred all three versions, they have available..


Even if they don't work for lasers, they will come in handy for something else.. Besides, just the components are worth more, than what they cost, if i were to buy them here...


The chargers started packaging today, which means i'll have them here before the end of next week.. After i test them, i will post the results.

 

[IgorT]

Good stuff!

The price difference is quite considerable.. I paid less for the three different chargers, than i would for one original Charge2Go.

So if only one works, it will be worth it.. And it will mean others will only have to pay $6 instead of around $20 for the original..

 

[chimo]

I have some news on this one. I knew it was driving that poor little bluray LD very hard. I started noticing the output was getting a little strange so I looked at the LD and noticed that the LDs window was getting burn marks.

I bit the bullet, opened it up, removed the LD and proceeded to convert it to an open can - the best news is that it survived the ordeal!!

I took some macro shots, but I have to wait till my wife is off the computer to post the pigs (I'm sending this from my 32GB iPod Touch - what a neat toy!!!)

Paul

 

[jake21]

cool i just bought to off ebay i hope they work out for me

 

[chimo]

OK here are the pics:

Freshly opened can:

The Business End

Stained Glass Window (note "burned" area)

 

[woop]

Re: BLuRay mod #2.  1xAA boost circuit.

wow. good job opening that thing up.
thats crazy, it burned the window
maybe its cos glass is pretty opaque to the upper end of the light spectrum, towards UV. you would think they would use quartz for the window.
is the power output any diferent now that there is no window?

 

[drlava]

Re: BLuRay mod #2.  1xAA boost circuit.

or was there crap on the window from before that then burned onto it?

 

[chimo]

wow. good job opening that thing up.
thats crazy, it burned the window
maybe its cos glass is pretty opaque to the upper end of the light spectrum, towards UV. you would think they would use quartz for the window.
is the power output any diferent now that there is no window?

I threw it on the Coherent thermopile head connected directly to my DMM (I don't have the amp board yet). I got 70-80uV. If it's around 1mW per uV that's about 70-80mW. I know it's being way over-driven. It stings on the skin instantly and will light a match instantly.

BTW, take a close look at the window. It looks to be cut in a hexagon. There looks to be a coating on it as well.

 

[chimo]

or was there crap on the window from before that then burned onto it?

Here is a little closer pic.  There's a lot of crud on the window from taking it off.  The area to note is inside the highlighted area.  Note the heavy burn marks and the spotted radial array in the darker area.

 

[nikokapo]

wow great job there, keep them coming!

 

[IgorT]

I threw it on the Coherent thermopile head connected directly to my DMM (I don't have the amp board yet).  I got 70-80uV.  If it's around 1mW per uV that's about 70-80mW.  I know it's being way over-driven.  It stings on the skin instantly and will light a match instantly.

OMG.. You are getting 70-80uV from a reader LD?!?

What is the current? How is this possible at all, without it dying?


I really wonder how long this one will live. Oh, did you also make a measurement with the window still on?

 

[chimo]

[quote author=chimo link=1199303658/15#27 date=1204774933]I threw it on the Coherent thermopile head connected directly to my DMM (I don't have the amp board yet).  I got 70-80uV.  If it's around 1mW per uV that's about 70-80mW.  I know it's being way over-driven.  It stings on the skin instantly and will light a match instantly.

OMG.. You are getting 70-80uV from a reader LD?!?

What is the current? How is this possible at all, without it dying?


I really wonder how long this one will live. Oh, did you also make a measurement with the window still on?[/quote]

It was about the same. It's surviving by luck and short duty cycles. :