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DIY Ophir LPM

Blord

Blord

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Me and offroadfreak8582 bought each an Ophir 20c head. This little sensor has everything that a fast response LPM needs. I use an old metal dataswitch for Centronics ports or parallel/printer ports. It has been laying on the shelf for more than a decade. Once time I though I am going to trash it but then I think I going to keep for someday. Well that day has finally come. :D

The original knob was used for on/off. It has more than 20 independent switches, all turn with one flip of the finger. I use three switches for each power source.
Instead of bolting or glueing everything together I use a Grippy Pad to hold the batteries in place. The size of the pad was just right. :)

The final result looks a bit retro.
Well here are the pictures. Thanks for watching. :thanks:

LPM%20Ophir-1.jpg

LPM%20Ophir-2.jpg

LPM%20Ophir-3.jpg

LPM%20Ophir-7.jpg

LPM%20Ophir-4.jpg

LPM%20Ophir-5.jpg

LPM%20Ophir-6.jpg
 
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Sweet build! I see you used 4 AA's to power you voltmeter, didn't quite have that much extra room. Doest you ophir also have a little trouble resting at zero?
 
Finished result looks GOOD! Easily as good as my Nospin.

@awillis2589 - Yup, none of them ever seem to want to rest at zero. Mine doesn't I know Offroad's and Blords also don't. At least not when I was testing them.
 
Yes, I use four rechargable AA batteries. That make a total of ~5V for the LCD panel.

The Ophir head is very sensitive to changes in ambient temperature. Mine hovers around 0.002 Volt
What is your deviation ?
 
There is a blue pot behind the LCD panel. Maybe it can compensate the Ophir value.
On the other hand 4mW on 2-3 Watt laser doesn't make much difference.
 
The blue pot doest make a difference I messed with it well having alligator clip to a dmm and it still had the extract same reading at rest as well as when metering.
 
Great looking build blord! Mine is hovering at 0.007 i believe. Can't wait to complete my build :) waiting for parts :)

Greetings,,

EDIT: If you want to be able to zero it you wil need an opamp. I dont really care as much, just meter it and then do minus starting value tadaa :p
 
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I might suggest adding some stress relief for all the wire exciting the enclosure so they don't get stressed, or the insulation doesn't wear. Maybe some grommets and electrical tape? You do not want to have to splice those again later.
 
offroadfreak8582 said:
Great looking build blord! Mine is hovering at 0.007 i believe. Can't wait to complete my build :) waiting for parts :)
Click to expand...

Your LPM will be the same as SmeerWorst version ? Bluefan said that this case is very cramped to work with. And you will need some serious metalworking on the aluminium case. But the case will be very nice if you pull it off. :drool:

Meatball said:
I might suggest adding some stress relief for all the wire exciting the enclosure so they don't get stressed, or the insulation doesn't wear. Maybe some grommets and electrical tape? You do not want to have to splice those again later.
Click to expand...

I saw the awillis2589 version of the case and I am going to make that USB port too on the back.
 
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offroadfreak8582 said:
Great looking build blord! Mine is hovering at 0.007 i believe. Can't wait to complete my build :) waiting for parts :)

Greetings,,

EDIT: If you want to be able to zero it you wil need an opamp. I dont really care as much, just meter it and then do minus starting value tadaa :p
Click to expand...

The ophir has an opamp built it. It doesn't seam like its just this batch so I'm satisfied.
 
I put in little pieces of paper with the deviation written on it for both of you guys. I don't remember what the values were (and sorry for the crappy ripped of paper pieces, but I had no printer paper left :p), but neither of them was anything extreme.

For myself, it really doesn't bother me. I just add to the result. I suppose it would be an issue for low power builds, but most of my lasers are well over 100mW, so +/- 4 mW wouldn't matter much anyway.
 
Blord said:
Your LPM will be the same as SmeerWorst version ? Bluefan said that this case is very cramped to work with. And you will need some serious metalworking on the aluminium case. But the case will be very nice if you pull it off. :drool:
Click to expand...

Yeah sort off :) but i have a good dremel and in theory a perfect plan :) but i will show that in MY ophir thread when it is done :p :p

Greetings,,
 
Aha, I found a little paper with +10 on it. I haven't got a clue what it means. The value is way off, it is +2 like in the fourth picture.
 
Blord said:
Aha, I found a little paper with +10 on it. I haven't got a clue what it means. The value is way off, it is +2 like in the fourth picture.
Click to expand...

One paper was +2 and one +10 i have the +10 one. I unpacked them when they got to me and forgot which one was which :p anyway you have the closest one to zero :)
 
You guys had me going crazy trying to remember the numbers... basically all I remembered was that they were both positive, whereas mine is negative.

@Offroad, I didn't keep either of them on for very long, maybe ~3-5 minutes tops, so chances are if you let it sit for a bit longer it will settle to under 10. Even if it doesn't there must be a way to adjust.

Usually mine starts off at -8 or so, and with time falls to around -4.
 
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