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My first build from scratch

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Just a suggestion... next build, mount the components on the top of the board or flip it over. This better protects them from that holding ring and from accidental batt. contacts. Nice build BTW. I've always liked that host.
 

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Hi guys, Thanks for the suggestions, and the DMM Help
comradmax

BTW I wondered why I had blown 2 DMM Fuses, now I know.

Thanks for pointing the correct setting out on the meter, I have zero experience in electronics before building this laser

jander6442
I am not entirely sure that would be possible to have components facing the LD as i think that the Aixiz Housing would obstruct the components I'll check though, thanks for the suggestion. Although the cells are alot smaller than the host compartment they have been packed in with paper to prevent movement.

Kevlar
You are right 2x3.0v cells don't last long until the laser becomes affected by lack of voltage, but I am using a LM317LZ (very small) for the regulator(I think that's what its called) as space is a serious issue with this host, and that extra heat could compromise the LD.
 

ped

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Welcome Carl.

+1 on not just your build, but your research before attempting a build.
Most people come on and make a topic "i wanna build a burnin' lazors like now".
Also, not sure if its been pointed out but your using a 1/4 carbon resistor? thats gonna get very warm, very quickly.
 

Toke

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Here is the datasheet for all/most of the variations of LM317 and lots of examples of applications.
(I must have for ones datasheet pdf directory. :))
Some are really small, I accidentally ordered 10 for surface mount. :D
When I opened the letter I realised why they were so cheap, 10c or so.
 
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Ped

I noticed the 10 ohm resistor was a different color to the other resistors I had but it never really meant anything, got new batch this morning in the post. Whats the difference between the blue and light brown resistors is it that 1 is 1/4 w and the other is a 1/2 w I just don't know. My head hurts from all the reading i've done over the last few weeks, I can only take so much in.

Toke

Downloaded thanks.
 

Kevlar

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Kevlar You are right 2x3.0v cells don't last long until the laser becomes affected by lack of voltage, but I am using a LM317LZ (very small) for the regulator(I think that's what its called) as space is a serious issue with this host, and that extra heat could compromise the LD.
The diode and the driver will take 6V so feeding 7.2V will give you a longer run time but the extra 1.2V will not produce enough heat to jeopardize the LD IMO. And besides, the voltage from your batteries will begin to drop immediately with a load on them. :yh:

Whats the difference between the blue and light brown resistors is it that 1 is 1/4 w and the other is a 1/2 w I just don't know. My head hurts from all the reading i've done over the last few weeks, I can only take so much in.
Yes, that would be how much Watts they are rated. Its hard to tell from your picture but I thought it looked like a 1/2W resistor, and I think the blue colored ones are 1W rated, but I could be wrong. Maybe Ped could answer this better but for this build, a 1/2W resistor should be OK. It never hurts to overcompensate though. :yh:
 
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I am in the process of aquiring 2x 3.7v RCR 2 Batteries for my build. Checking web now.

Kevlar wrote
'It never hurts to overcompensate though' I guess that makes me an accidental hero. LOL
 

ped

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The colour varies between manufacturers.

If you look at the pic, one of the smallest resistors, is actually the 1R 2W i use for dummy loads, and its blue.

 

Kevlar

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The colour varies between manufacturers.

If you look at the pic, one of the smallest resistors, is actually the 1R 2W i use for dummy loads, and its blue.

Good to know, thanks Ped!! Maybe if Carl took a close up of the ones he is using it would be easier to tell.

Just bought 2xCR2 3.6v Batts and a Charger.

Great
Very nice, should work great!!
 
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Just tested the DMM in 200m V as instructed, weird results,
Resistors used

cells reading 5.98v

0.25w 1r : 1 ohm brown blue gold red


0.25w 2r7 : 2.7 ohm red blue gold gold

1.25/3.7 = 0.3378
0.3378 * 1000 = 337.8

DMM reads 157


Any ideas
 

Toke

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That does look odd.
Try remove the batteries and measure the resistance between the out and adj legs of the LM317. It should be 3.7 Ohm.
Then measure the resistance across the resistor on the test board.

You should also, with power on measure the voltage between LM317 out and adj, just to check that it is fully regulating at 1.25V.
 

Toke

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LM317 out and adjust legs read 1.5 ohm
Not good. They are supposed to be connected by a 1 and 2.7 Ohm resistor in serie.
Test board res 1.7 ohm
Should be a 1 Ohm resistor, but it is quite haed to get accurate measurements that low. The pins and wires have resistance of their own, or rather the connection between pin and measuring point has.

LM317 out & adj power on 0.11v
Bad.
Here you should be measuring across your current setting resistor at regulated load.
If the 1.5 Ohm is accurate you have a pretty low current 110mV/1.5Ohm=73mA.
It is not possible unless your batteries are almost dead.

Try check your current setting resistors again (1+2.7), then power the thing up with test load and measure the voltage from the batteries.
After that you try set the DMM for 10A and insert it in the battery line to measure how much the circuit is using.
 

Kevlar

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This is just a thought and I could be totally wrong. I have never used a DMM like yours Carl, I have a cheap one from RS. I hoping Toke could weigh in on this. If you have your leads on your DMM plugged into the wrong holes on the DMM, is there some kind of internal resistance in the DMM that can affect the readings?
 

Toke

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This is just a thought and I could be totally wrong. I have never used a DMM like yours Carl, I have a cheap one from RS. I hoping Toke could weigh in on this. If you have your leads on your DMM plugged into the wrong holes on the DMM, is there some kind of internal resistance in the DMM that can affect the readings?
You have an excellent point there.
I kind of forgot to mention that you have to move the red wire depending on what you want to measure. :yabbem:
The black is set in com.
10A will have it's own fused hole.
Up to 200 mA may have it's own, or be combined with V, Ohm, uF, etc.

If you are effectively measuring on an unconnected hole the result will likely be some semi random low reading from ambient electric noise.
 




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