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[Pic Heavy] My DIY LPM by Kalmito

Kalmito

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:bowdown: Big THX for:

MarioMaster (circuit, help)
ARG (data logger, help)
Trevor (Peregrine)
honeyx (help)
Zeebit (help)

Thanks for watching! :beer:
 



ARG

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Looking good mate! :D

Nice job on the DIY PCB :)
 

crazyspaz

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Frickin sweet! How much did the whole thing cost you? Looks great as well.
 

Kalmito

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Looking good mate!

Nice job on the DIY PCB
THX ARG! :)

Frickin sweet! How much did the whole thing cost you? Looks great as well.
THX crazyspaz!
1x Circuit
1x display
1x switch
2x DC connector (male, female)
2x TEC
2x Headsink
1x Datalogger
1x project box

cca 100 €
 

crazyspaz

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Not bad price. I know you can get a Radiant Electronics meter for 100USD (~40USD less than yours), but honestly, I would rather build one myself. Its just cool!
 

honeyx

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THX ARG! :)



THX crazyspaz!
1x Circuit
1x display
1x switch
2x DC connector (male, female)
2x TEC
2x Headsink
1x Datalogger
1x project box

cca 100 €
This is quite a lot but still worth it. Great work on this. :)

In general you can build it for less than $50. Mine was around $30 but I had some parts already around like a CPU heatsink. But well mine is also without datalogging.
 
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Kalmito

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this is quite a lot but still worth it. Great work on this.

In general you can build it for less than $50. Mine was around $30 but i had some parts already around like a cpu heatsink.
thx! :)
 

honeyx

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I just wounder how you calibrated it. What did you use for calibration?
 

honeyx

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Hm, unless you got them metered elsewhere with a calibrated LPM the assumed power isn´t a good value to calibrate a DIY LPM. 1.6A in doesn´t mean you get 1.6W out. The output can be somwhere between 900mW and at best 1.6W. All depending to the efficiency of each diode, the optics and your batteries quality.

You better build a calibration tool like I did or get your lasers metered with a calibrated LPM by using a lab powersupply as the power source while they get metered.
 

Kalmito

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Hm, unless you got them metered elsewhere with a calibrated LPM the assumed power isn´t a good value to calibrate a DIY LPM. 1.6A in doesn´t mean you get 1.6W out. The output can be somwhere between 900mW and at best 1.6W. All depending to the efficiency of each diode, the optics and your batteries quality.

You better build a calibration tool like I did or get your lasers metered with a calibrated LPM by using a lab powersupply as the power source while they get metered.
How to prepare calibration tool?
 

honeyx

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How to prepare calibration tool?
You need a small and thin aluminum plate that fits on the TEC. 10x10 Ohm SMD resistors and for example a constant current source like a LM317. You solder the SMD resistors to an "S" while making sure the buttom of this construct is totally flat and glue it on the aluminum plate by also using some thermal paste for better heat transfer. Then of course some leads going to the constant current source. On top of the plate with the resistors you glue some sytyro foam as an heat isulator so the entire heat will be directed to the TEC.

Now when you set the constant current source to 50mA you will get 250mW. At 100mA you will get 1W and at 200mA this will produce 4W of heat.

This is simple U=R*I and P=U*I calculation.

While calibrating also use some thermal paste between the aluminum plate and the TEC and apply some preasure to it for more accurate results.

When calibrating up to 1W you need a powersource with something more than 12V output and for 4W you need more than 22,5V.

I´ve calibrated mine this way and then measured the output with some lasers that got metered before with a laserbee.
 




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