PHR-803t in Hotlights host with LM317 driver

Since it had been a couple months since I built a laser I decided it was time to do something with a PHR diode that's been sitting on my desk since I pressed it in October.

Update: I've added some more pictures in the next post and answered a couple questions I've received. Also for some reason some of my pictures are randomly not showing up even though i haven't modified anything on Flickr. If you click on them they will open to their page on flickr.



2011-01-15_05-24-08pm by ltkernelpanic, on Flickr

Hotlights host from Mohrenburg. Nice smaller host but still has a beefy heatsink and comes with a carry case.



2011-01-15_06-15-09pm by ltkernelpanic, on Flickr

Parts list:

Hotlights host kit (includes some of FP's awesome wire)
10 ohm 1/4w resistor
5.1 ohm 1/8 resistors
LM317T voltage regulator used as a current regulator
PHR-803T pressed into an Aixiz module with standard acrylic lens
3x 10440 LiIon rechargeable batteries

Not shown is the 3xAAA battery holder inside the host. If you decide to use 10440s DO NOT get the protected ones. They will not fit!



2011-01-15_07-05-42pm by ltkernelpanic, on Flickr

Like the Guidesman hosts you can easily remove one of the ribs from the pill/spacer to make room for your driver. I cut as far down as I could with a razor blade then used needle nose pliers to pull the soft plastic out.



2011-01-15_08-07-23pm by ltkernelpanic, on Flickr

Test fitting the LM317 after its output and adjust legs were bent to fit . Also test fitting the resistor package after soldering the two 5 ohm resistors in parallel which was then soldered to the 10 ohm in series for a total of ~12.5 ohms. (the 5ohm were actually 5.1 ohm. I ordered the wrong part for a previous build and deiced to use up a few)



2011-01-15_08-07-55pm by ltkernelpanic, on Flickr

The resistor package on top of the LM317 before soldering. At my target current of 100ma the resistors need to be able to withstand about .13w which my 1/8w resistors in parallel should handle fine but to be safe I attached the 1/4w to the output leg when I made the final joints.



2011-01-15_09-24-28pm by ltkernelpanic, on Flickr

Double checking everything before soldering on the batt + and LD+ leads.



2011-01-15_09-25-05pm by ltkernelpanic, on Flickr

Another shot showing the completed driver.


I didn't take any pictures of the final assembly but all that was left to do was bend the input leg to fit into the smaller left cavity of the pill, shrink the heat shrink tubing and attach the leads from the host and to the diode. o prevent any shorts I put a piece of electrical tape over the top of the plastic pill to keep it from shorting against the bottom of the positive battery contact. I also put a piece over the top of the positive battery contact to prevent it from shorting to the bottom of the heatsink. One thing I forgot to do initially was solder a bridge between the case pin and LD- to complete the ground. One of the left over resistor leg trimmings worked perfectly for that.



2011-01-16_10-41-55pm by ltkernelpanic, on Flickr
The completed laser.


2011-01-16_10-44-16pm by ltkernelpanic, on Flickr


2011-01-16_10-44-43pm by ltkernelpanic, on Flickr

Nice and snug!


Beam shots! I really need to get a fog machine. The beam is a very nice deep violet even though it looks kind of blue in the pics.


2011-01-16_10-22-30pm by ltkernelpanic, on Flickr


2011-01-16_10-21-24pm by ltkernelpanic, on Flickr


2011-01-16_10-29-11pm by ltkernelpanic, on Flickr

LPM testing.



Two minute LPM test.


Screen shot 2011-01-17 at 12.05.31 AM by ltkernelpanic, on Flickr

Even though it says 89mw I'd say it's actually 87 because that's what I measured it at after I finished the build. I suspect my LPM was picking up some heat from my heater because after turning the laser off it was bouncing from 1-2mw. Finally to answer the inevitable questions - yes it burns and lights regular red matches almost instantly. I don't have any balloons handy and they tend to startle the dog.

This project was pretty cheap to complete wouldn't be too bad as a beginner's build. Not counting consumables it used only about $35 (plus S&H) in parts not including batteries and charger. If you'd rather not harvest and press your own diode add another $5-10 to the final cost. The planning took a couple hours but the build time itself was less than an hour and was pretty easy if you have the right tools and some soldering skills. Feel free to ask questions and I'll try to answer them the best I can.

I've decided to disassemble my build and add a few pictures of the internals since I've had a few question asked about it.


The most common question is "Where is the negative/ground connection?" Unless your host has a circuit board (which this one does not) that you can solder both your negative and positing wires to you need to do what I briefly mentioned in my previous post. By bridging the case pin, the pin on the right in the picture below, with LD- pin the diode case, aizix module and heatsink become the path to the bare metal on the top of the host completing the circuit.


2011-01-30_06-28-00pm by ltkernelpanic, on Flickr

Case pin (right) bridged to LD- to complete the path to ground. I forgot to put heat shrink on before soldering so I used a bit of electrical tape to insulate the connection before closing up the laser.



2011-01-30_06-19-26pm by ltkernelpanic, on Flickr

With the pins bridged when the heatsink contacts the bare metal of the host the negative path to ground is competed. The bit of paint on the top won't hurt anything but if there was much more I would use some fine sand paper to remove it.



2011-01-30_06-26-56pm by ltkernelpanic, on Flickr

The wiring between the positive contact in the host and the diode. I could have gotten away with shorter wires but since there's plenty of room in this host for the extra I like having it in case I ever need to disassemble it.



2011-01-30_06-30-31pm by ltkernelpanic, on Flickr

I used a piece of larger diameter heat shrink tubing to cover my resistors. I only shrank it enough so it wouldn't fall off but I could slide it off to get to the resistors if needed. Electrical tape would have also worked.



2011-01-30_06-29-47pm by ltkernelpanic, on Flickr

The driver in its home in the plastic pill/spacer. Be sure to put a piece of e-tape over the top of it to prevent the bottom of the positive contact from shorting against the LM317's pins. Also put a piece on top of the contact to prevent shorting to the heatsink.



2011-01-30_06-34-12pm by ltkernelpanic, on Flickr

The reason you can't use protected 10440s with this host. The unprotected ones barely fit! Be careful to insert the battery holder with the end marked + first since the driver circuit does not have reverse polarity protection! You can add it by putting a 1N4001 diode between the positive connection of the host and Vin of the LM317. You'll lost about .7-1.0v due to the diode's voltage drop but it'll keep your LD from frying if you have a reverse polarity. You'll want to test them with your DMm from time to time to make sure they don't drop below 2.75v. You'll likely notice your laser is much dimmer by the time they get that low since the driver and diode need 7v to work.

The last question is "What resistor(s) do I need for X mA?"

The formula is 1.25 divided by the desired current in amps. If you want to drive it at 100ma you take 1.25/.1 and get 12.5 as the needed resistor value in ohms. If you have a resistor and want to know how many mA you'd get with it take 1.25 divided by the value of the resistor in ohms then multiple that result by 1000. Using a 12.5 ohm resistor as an example (1.25/12.5)*1000= 100ma which is the same result as above. Just make sure it's rated to handle the amount of wattage that will be passing though it. I highly recommend this site

LM317 Current Calculator - Electric Circuit

for calculating the resistor value since it will also tell you how many watts the resistor needs to be rated for.

Some pictures are not working.

Nice to see another kind of build in this host.
This is an AWESOME first build people could do.

Any idea what your total build cost came out to?

Very nice, simple build and a great build thread with tons of good info and pictures. Perfect for a laser noob like me. Thx.

That's very nice and helpful, since I've got one of these hosts in the mail, and I will
probably use a lm317 as a drive as well. Nice pictures too. :gj:

Mohrenberg said:

Some pictures are not working.

Nice to see another kind of build in this host.
This is an AWESOME first build people could do.

Any idea what your total build cost came out to?

Click to expand...

WTF. I fixed one that had been messed up since a day or two after the original post and they all showed up fine when I submitted the post last night. As of now all are showing up. You can always click on them to see them on flickr. *baps* flickr.

From what I can tell there's pretty much no duty cycle at this current. I should have ran it for a few minutes while I had it apart to see how warm the LM317 gets. I know when testing my 635 build at 42ma what was supposed to be a 30 minute test turned into a 13 hour test when I forgot to unplug it before going to bed. The LM317 wasn't even warm when I found it the next afternoon.

One last thing I should add to the previous post is that the metal back of the LM317 is facing the rounded part of the spacer not the flat part in the middle so the pins are reversed ( Vin, Vout, Adj) from the way you'd normally look at a LM317 with the metal side down and tab up (Adj, Vout, Vin). I did it that way for two reasons. The first is I wanted to isolate Vin from the other pins and secondly by having the metal back face out it can act as a small heatsink. I guess a third reason would be the resistors would only fit in the bigger compartment.

Total cost breakdown

Host $15 (from Mohernberg)
Diode: $9 (from modwerx)
module $3 (i think. I bought a 5 pack at a discounted price from modwerx)
Driver parts ~$2 (from digikey)
Batteries: $12 (Battery Junction)

Total: $41 + S&H.


I couldn't really calculate what the S&H was because these parts were bought along with parts for other builds but I'd guess maybe $10-15 at the most. I already had a charger but if you need one add about $15 to the total. If you use an LM317 driver as far as I can tell you are limited to using 3x10440s since I don't know of any batteries with more than 250-300 mAh capacity that two of would fit into the host and provide 8.4v on a full charge. There are other battery options if you use a flexdrive or microboost instead.

I also didn't include the cost of consumables such as solder, flux, heat shrink tubing, etc. If you don't have a diode press I'd consider spending the money for one. I got mine from modwerx but there are a couple LPF members sell them as well.

no capacitors?

No. This build uses the simplest form of the "DDL" driver. Since I used the host as the negative contact i'm not sure how you'd even wire one in without having to isolate the module from the host. You'd still have to establish a place to attach a ground that would lead o the cap and eventually the diode. I suppose you could put a wire between the top of the host or between the isolated module and heatsink if you have some ultra fine wire.

Hi
Nice build. I'm going to build this the same way, with another host and LPC 815 Diode(set 380mA).
I'm wondering what capacitors are for?
Moreover, how can I prevent the diode from getting destroyed by setting the batteries in the wrong way? That would be a really annoying mistake..
And is the diode polarity always the same? (Got a graphic)

+1 to you Sir! i like the blue hotlight host with a beefy heatsink , that shows how much we love our diodes.. 89mW is very reasonable from a phr diode, and with three 10440's you would get quite a long-runner!
The LM317's overheating wouldnt be a problem at 100mA's
I think there is no design flaw, and excellent work!! check mines too..