My first build from scratch

Carl Witcombe · Sep 29, 2010

Hi all

My name is carl, I Live in South Wales in the UK and I want to share with you my first homebrewed project.

£2 Host from Tesco
16x DVDRW diode from pioneer
Homebuilt DDL aka LM317 Driver.

Anyway, Having researched continuously for weeks on how to guides, I finally completed my first build.

Heres some pics

I know the lase is very dim thats because I got carried away with my new toy and drained the batts.

Great forum lots of usefull info

Thanks all.

EDIT I have now included an AVI Movie for your veiwing pleasure. The Laser pointer in question has an updated Home Made Driver using an AMS1117 Regulator which can supply upto 1 Amp, The target is a single peice of Black Electrical Insulation Tape

Enjoy

If you like it make a comment

Kevlar · Sep 29, 2010

This is pretty good for your first build!! Very nice. You went about it the right way and did your research first instead of just coming onto the forum asking everyone to TELL you how to do it or having other people do the research for you...

For that you deserve some rep, +1.

I hope other people new into the hobby will see this and learn the right way of doing things. You sir will fit in nicely here.

Carl Witcombe · Sep 29, 2010

Kevlar Thank you sir, I wasn't expecting any rep just yet so thanks again I hope to have more builds added in the near future.

My other build is a 1W 445Nm Build a laser kit from *****************.com got the Kit except the 1w diode was missing, hope to be sorted soon. I may have been a little offish with the message I sent in relation to the missing LD. I'm sure they'll sort it pretty quickly.

Kevlar · Sep 29, 2010

I know the guy who owns that store. He is a decent guy, it must have been an oversight, I'm sure he will take care of you.

Carl Witcombe · Sep 29, 2010

Yeah, As soon as I messaged him I got a refund on shipping of one of the items pretty much instantly so good on him for that.

A question.

I built a dummy load, when I connect it to a few LM317 drivers I built, the readings are way off, does the readout depend on the battery voltage?

Icluded a Pic

chipdouglas · Sep 29, 2010

+1 on your first build very nice

please take a couple pics of your power supply and your driver hooked up to your dummy load. as long as you apply the correct voltage for your driver your dummy load should be fine.

michael.

Carl Witcombe · Sep 29, 2010

chipdouglas Thank you

Heres the pic

I know its crude, I apologise for that

Power source is from 2x cr2 batteries producing 5.92v combined.

My calculations get me to 98.42Ma, as you can see the DMM states that the Ma draw is 40.1Ma, Worked out using Ohm's Law:-

LM Ref V Total of resistors
1.25 / 12.7 Ohms * 1000 = 98.425197

Can't think of any other useful info to include.

Oh yes and the pot is a 100ohm, turned up full (No resistance I presume)

Thanks for replies

Kevlar · Sep 30, 2010

I can't quite tell from your picture, do you have your DMM set on mA or mV?

comradmax · Sep 30, 2010

Aren't CR2's 3.6V, so 2x should give you 7.2V? You also mentioned in your first thread that the laser is dim because the batteries are drained, so maybe you just need to charge them

Also you can try connecting the DMM in series with the test-load and setting it to read mA directly.

Also great 1st build, very cleanly made! +1 rep from me, even tho I only have 1 point to give anyway

Kevlar · Sep 30, 2010

as comradmax said, you could connect the DMM in series with the test-load and setting it to read mA directly but if you are measuring across the resistor, you DMM needs to be set to V

EDIT: Hey, I just noticed, a fellow Bostonian!!! :beer: I'm actually in Western Mass but its a small state. I think your the first!! Now I don't feel so lonely. :crackup::crackup:

Never mind, I got them mixed up, I think it depends on the battery. I've seen them in 3.0V and 3.6V.

comradmax · Sep 30, 2010

Carl, I just saw Kevlar's post and looked at your pic again. It looks to me like you do have the DMM set to measure mA, but you need mV. What you have there is measuring current through the DMM

So you are prolly getting that ~100mA from the driver, it's just now getting split ~60/40 between the test-load and DMM. The 1Ohm resistor on the test-load is just a trick to allow current reading with a voltage meter, because it's easier to connect it parallel to the resistor while the whole thing is running, no need to disconnect and insert the DMM in series.

Kevlar, you're right, I dont know if i've noticed anyone from MA either! Nice collection of lasers you got there... I need to get/make some of my own, maybe then we can have an LPF Mass Meet

Carl Witcombe · Sep 30, 2010

Hi

Kevlar

Not sure about DMM setting, but have included a pic Decyphering is appreciated Thanks. Primary cells i'm using and they are 3.0v.

Comradmax

The cells have been changed they are not at full charge as they have had limited use. outputting 5.92v out of a possible 6.0v. Thanks for the rep . much appreciated.

also comradmax Please explain the following quote
'Also you can try connecting the DMM in series with the test-load and setting it to read mA directly'

Connect DMM in series?
Which setting would be Ma?

Carl

Catch you all tommorow thanks sleeptime at 1am

Toke · Sep 30, 2010

Yes, it looks like mA setting.
Another mistake to look out for with test loads is the lanes vs. islands issue with print boards.

(It does happen)

ETA: Connecting in series just means that you take one of the wires from the test load and kind of replace it with the whole DMM. Like remove one test load wire from the driver and stick a meter pin in it's place, then hold the other DMM pin and the free end of the wire together.

Your current/pictured setting is 200 mA, it may be too low and you might blow the DMM fuse.
The 10A setting may work or may have too low resolution to give an accurate reading.
Your best choice to set the DMM for mV and measure across the resistor on the test load.
That is a 180 turn to 2000m.

comradmax · Sep 30, 2010

also comradmax Please explain the following quote
'Also you can try connecting the DMM in series with the test-load and setting it to read mA directly'

There are 4 meters in this picture. 3 read the voltage parallel to the "load", which are the resistors; 1 reads current in series, it breaks the circuit and now all of the electricity is going through it.

Like Toke said, just turn your DMM dial exactly 180 deg

chipdouglas · Sep 30, 2010

also you need more volts. your dummy load needs 2.8 and your ld needs over 4. so it is always advised to use the same voltage to set your driver via dummy load that is going to run the laser.
@ comrad.... cr's are generally 3v. and rcr are generally 3.6

Kevlar · Sep 30, 2010

comradmax said:
maybe then we can have an LPF Mass Meet

That would be cool. I keep hearing about laser meets in FL and other places but none around here. Maybe we could start one up!!

chipdouglas said:
also you need more volts. your dummy load needs 2.8 and your ld needs over 4. so it is always advised to use the same voltage to set your driver via dummy load that is going to run the laser.
@ comrad.... cr's are generally 3v. and rcr are generally 3.6

Actually he is using a 16X Diode, I think these are the same "Senkat Reds" which, I thought, only needed 3V. So 3V is needed for the driver and 3V for the diode. I would say 6V minimum. You should always try and get as close to the required voltage as you can. If it was me, I would probably go a smidge over, say 2X3.6V Li Ions because as soon as you hook it up, the battery voltage will start to drop and you won't get that much run time. The extra voltage you feed it will get dissipated as heat from the driver. You could always put a small heatsink on the LM317 chip for that.

And set you DMM according to the pic comradmax posted, then re-test.

My first build from scratch

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