Starting a new project

[andy_con]

i was in maplins the other day and saw this case and thought hm thats looks a good size and shape lets get one. so am now craming lots in there to make a 5-6watt 445 modules.

additional pics will follow as and when

the actual lid measures just 120mm by 95mm, so its going to be a tight build

[andy_con]

looks like its going to work, even if it is a bit tight

[andy_con]

you know its a tight build when you have to mod the mirror mounts

[RGB LASER VERKOOP]

i love this building pictures.

i have a question, why you using resistors ?
the flexmod will set the current, so why need them ?
it's extra heat inside

[Solonar]

i love this building pictures.

i have a question, why you using resistors ?
the flexmod will set the current, so why need them ?
it's extra heat inside

Looks like he's driving direct from a PSU for testing.

[p1t8ull]

Nice work Mr C, tight as a ducks chuff in there!

This will be at the LEM, yes?

[andy_con]

cos i was advise that you need resistors when running 4 diodes off one driver. dont ask me im crap at electronics.


indeed very tight, yes it will be at the meet boss

[RGB LASER VERKOOP]

hope someone can explain me the risitors.
becourse i see them only as lost of current and heat up the housing!

pitty i can not see it there...
but i love see the pictures here..
good forum to share !

[kiyoukan]

they are balancing resistors
Not all the diodes have the same resistance when running and thus some will take more current than others the resistors are there to make sure they all get the same current.

[RGB LASER VERKOOP]

i think not!

the resistors have the same values, then you need potentio meters variable risitors.
and i think the diode current and drempelspanning (sorry dutch) are pritty close powers (1,1 till 1,3W) and we calculate with 1w so there no problems.
if you ask me....
but maybe i am wrong, i just not understand it, are there electronic experts here who can explain ?
i am a electric expert, not electronic

laser greets joost

[planters]

I like your tight build, but the retaining plates appear to back up 4 diodes simultaneously. Having gone this route, this can make fine tuning diode rotation difficult. Am I miss-reading this or have you worked around this alignment challenge?

[andy_con]

What issues?

I had a funny diode I had to swap out, only took a few mins and had no rotation issues.

This method works great for me

[kiyoukan]

Andy i am correct in saying those are balance resistors right?
You put them on their to make sure each diode gets the same current.

[RGB LASER VERKOOP]

no that can not be correct,. becourse you can not change the risistor so can not balance anything....

[kiyoukan]

i am almost positive they are balancing resistors. someone with more of a rep will come in and confirm.
There is a good reason you dont attach 4 diodes to 1 driver without those resistors.
I have those same style resistors on my old dual loc build that used 1 driver.

[logsquared]

Diodes are current devices... meaning they don't change there voltage much with current. When putting diodes or transistors is parallel (all + tied together and all - tied together) a balancing resistor is need. With out the resistors the diodes would have the same voltage across them. But due to variations in the VI curve they would all draw different currents from the driver. the resistors act as a equalizer. Joost is correct in thinking a variable resistor would be better. However, its common practice to use a low ohm high tolerance resistor to give satisfactory results.

If Andy was to wire the diodes in series (+ tied to - to + and so on) the resistors would not be needed because the current in a series circuit is always the same. This lets each diode "set" its own voltage so to speak. In this case the power supply would have to deliver less amps but more voltage.

Hope this helps.

[RGB LASER VERKOOP]

thanks !

serie sounds good, my red also in serie!

[LaserCo]

These resistors (Very Low Ohms) will allow for current monitoring of each of the diodes
These are not to keep the current the same between all the diodes, the drivers are doing that.
They balance out the load drawn by each of the drivers, they could be low ohmage fuseable resistors also but I doubt it in this case.

Edit: Wow this is a great compact job andy!! Thanks for sharing!

[logsquared]

Look at the third picture in the second post.... Only one set of alligator clips suggesting all are in parallel. My guess would be he is going to use two flexmods with 4 diodes each. Not 8 separate drivers. Could be wrong though.

These resistors (Very Low Ohms) will allow for current monitoring of each of the diodes
These are not to keep the current the same between all the diodes, the drivers are doing that.
They balance out the load drawn by each of the drivers, they could be low ohmage fuseable resistors also but I doubt it in this case.

Edit: Wow this is a great compact job andy!! Thanks for sharing!

Edit: And he may have 1 resistor for each of the drivers where they connect to the power supply! he should!

[andy_con]

yes 4 diodes per driver so two drivers in the module

the next module will be 10 diodes and 10 drivers in the module

[LaserCo]

Look at the third picture in the second post.... Only one set of alligator clips suggesting all are in parallel. My guess would be he is going to use two flexmods with 4 diodes each. Not 8 separate drivers. Could be wrong though.

aligator clips: I payed no attention to the clips, I look now and I cannot tell what they connect to.
8 drivers: I meant diodes, whoops

Yes he is using two drivers each powering 4 diodes with a current monitoring point inbetween, the resistors.

[logsquared]

Yes he is using two drivers each powering 4 diodes with a current monitoring point inbetween, the resistors.

Yes, it is a good place to measure the current. But they are primarily there to balance the current between diodes.

[andy_con]

rushed but finished (ish)

needs a bit of tweaking still but ready for the meet

[kiyoukan]

hey i noticed you only use half the screws in the flex mounts.
Are the other 2 not needed? as long as you only need to go down and to the right?

[andy_con]

I use a m2 grub screw as they take up less space