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Hello all, I just thought I'd post info about my project since I thought it was a bit unique and might be useful to others starting a project.
Type: PHR-803T 405nm
Current: ~90mA
Output Power: 107mW (Measured with IR thermometer)
Style: Flashlight Host, 14500 Battery
Total Project Cost: ~$40
~$10-15 Flashlight host (Ebay, ages ago)
~$3 Various parts (Digikey/Mouser, stuff I had laying around)
$2.15 (x3) CC LED boost driver (DealExtreme)
$2.92 Sure module with included acrylic lens, back cut out (HighTechDealz)
$2.36 14500 Battery (DealExtreme)
$17 PHR Diode (Ebay, yeah I know it's a bit overpriced)
End result:
Step 1: Research
So I have been planning to do a couple builds, one with the PHR and another with an SLD1236VL red laser, and had ordered some surface mount LM317's. However, there was the problem of battery voltage. The LM317 has a voltage drop of about 2V or so, meaning I'd need a battery voltage of at least 7V for the Bluray. So seeing as my only flashlight hosts were 3-AAA, that wasn't really feasible. I also knew how to make a constant current driver with a transistor, current sense resistor, and MOSFET, via this Instructable, and it turns out this type of driver has a much lower voltage drop, just the voltage drop of your current sense resistor in theory. Then I discovered that I had a few of these LED drivers laying around: DealExtreme: $6.46 AA and 14500 Circuit Board for 3.7V LED Emitters 3-Pack (1.5V~4.2V Input)
Turns out these were perfect, they are constant current boost drivers, and open circuit, they produce about 6.6V, just a little more than I'd need for the MOSFET drivers.
Step 2: Putting together the host
So now my plan was to put that boost driver in a flashlight host, and connect it to a female header that I could plug in a laser/Aixiz module with a driver into. I drilled a 1/2" hole into the lens cover and reflector to fit the Aixiz, and drilled another hole in the aluminum cylinder that previously held the LED. After lots of hot gluing and a little soldering, the end result is this:
The host was designed for one of those 3-AAA cartridges, but after an hour or so of use, they burned out, so I stuffed some cardboard in there and put a longer spring on the cap, and now it's a AA-powered host! Yay, boost converters!
Update: Switched to a 14500 Li-Ion battery and replaced cardboard with 1/2" PVC. Boosted the power by about 25%
Step 3: PCB/Driver
This part was easy, but very tedious. I just reused the design for my IR burner's driver.
I uploaded the schematic/board Eagle files below, if you want it.
Here's the schematic:
Here's the board:
The two jumpers J1 and J2 are just for a jumper wire, I couldn't get everything to connect on just a one-sided PCB.
The diode is for reverse polarity protection, it is a 3A Schottky with a voltage drop of only 0.3V at 100mA, so it doesn't hinder performance at all.
The two capacitors are for ESD protection, though they probably wouldn't do much of anything. I tried to come up with a design using some TVS diodes I ordered, but it just wasn't practical, at least not being driven at a lower voltage like this.
The 1 Ohm resistor was initially there for measuring the current, but it's not really necessary since it's a linear driver, I could just measure current through the whole circuit externally. The 5.6 Ohm resistor is the feedback resistor, calculated via the following: Iout = 0.5/R.
The MOSFET is the series-pass element, whose resistance is raised or lowered to keep the current the same.
The BC817 transistor is a generic NPN transistor that controls the voltage to the MOSFET gate by monitoring the voltage/current at the feedback resistor (not really sure how this part of the circuit works, actually).
Lastly, the 100k Ohm resistor is just to "pull up" the MOSFET's gate to the input voltage. If this isn't present the MOSFET will just stay off, or at whatever lowest voltage the transistor provides.
Here's the pre-etched boards, after fixing up some broken traces with sharpie:
Boards etched, stripped, and drilled:
Parts dry-fit:
Finished module (the driver was a little too big to fit in the Sure housing):
Success!:
Obligatory beam shot:
Obligatory match lighting:
Cool fluorescence in a wine glass:
Since the Sure module back didn't fit my driver, I ended up just hot gluing the heatshrinked module to the lens cover, but it is pretty easy to remove and add in a new laser if I decide to.
Type: PHR-803T 405nm
Current: ~90mA
Output Power: 107mW (Measured with IR thermometer)
Style: Flashlight Host, 14500 Battery
Total Project Cost: ~$40
~$10-15 Flashlight host (Ebay, ages ago)
~$3 Various parts (Digikey/Mouser, stuff I had laying around)
$2.15 (x3) CC LED boost driver (DealExtreme)
$2.92 Sure module with included acrylic lens, back cut out (HighTechDealz)
$2.36 14500 Battery (DealExtreme)
$17 PHR Diode (Ebay, yeah I know it's a bit overpriced)
End result:
Step 1: Research
So I have been planning to do a couple builds, one with the PHR and another with an SLD1236VL red laser, and had ordered some surface mount LM317's. However, there was the problem of battery voltage. The LM317 has a voltage drop of about 2V or so, meaning I'd need a battery voltage of at least 7V for the Bluray. So seeing as my only flashlight hosts were 3-AAA, that wasn't really feasible. I also knew how to make a constant current driver with a transistor, current sense resistor, and MOSFET, via this Instructable, and it turns out this type of driver has a much lower voltage drop, just the voltage drop of your current sense resistor in theory. Then I discovered that I had a few of these LED drivers laying around: DealExtreme: $6.46 AA and 14500 Circuit Board for 3.7V LED Emitters 3-Pack (1.5V~4.2V Input)
Turns out these were perfect, they are constant current boost drivers, and open circuit, they produce about 6.6V, just a little more than I'd need for the MOSFET drivers.
Step 2: Putting together the host
So now my plan was to put that boost driver in a flashlight host, and connect it to a female header that I could plug in a laser/Aixiz module with a driver into. I drilled a 1/2" hole into the lens cover and reflector to fit the Aixiz, and drilled another hole in the aluminum cylinder that previously held the LED. After lots of hot gluing and a little soldering, the end result is this:
The host was designed for one of those 3-AAA cartridges, but after an hour or so of use, they burned out, so I stuffed some cardboard in there and put a longer spring on the cap, and now it's a AA-powered host! Yay, boost converters!
Update: Switched to a 14500 Li-Ion battery and replaced cardboard with 1/2" PVC. Boosted the power by about 25%
Step 3: PCB/Driver
This part was easy, but very tedious. I just reused the design for my IR burner's driver.
I uploaded the schematic/board Eagle files below, if you want it.
Here's the schematic:
Here's the board:
The two jumpers J1 and J2 are just for a jumper wire, I couldn't get everything to connect on just a one-sided PCB.
The diode is for reverse polarity protection, it is a 3A Schottky with a voltage drop of only 0.3V at 100mA, so it doesn't hinder performance at all.
The two capacitors are for ESD protection, though they probably wouldn't do much of anything. I tried to come up with a design using some TVS diodes I ordered, but it just wasn't practical, at least not being driven at a lower voltage like this.
The 1 Ohm resistor was initially there for measuring the current, but it's not really necessary since it's a linear driver, I could just measure current through the whole circuit externally. The 5.6 Ohm resistor is the feedback resistor, calculated via the following: Iout = 0.5/R.
The MOSFET is the series-pass element, whose resistance is raised or lowered to keep the current the same.
The BC817 transistor is a generic NPN transistor that controls the voltage to the MOSFET gate by monitoring the voltage/current at the feedback resistor (not really sure how this part of the circuit works, actually).
Lastly, the 100k Ohm resistor is just to "pull up" the MOSFET's gate to the input voltage. If this isn't present the MOSFET will just stay off, or at whatever lowest voltage the transistor provides.
Here's the pre-etched boards, after fixing up some broken traces with sharpie:
Boards etched, stripped, and drilled:
Parts dry-fit:
Finished module (the driver was a little too big to fit in the Sure housing):
Success!:
Obligatory beam shot:
Obligatory match lighting:
Cool fluorescence in a wine glass:
Since the Sure module back didn't fit my driver, I ended up just hot gluing the heatshrinked module to the lens cover, but it is pretty easy to remove and add in a new laser if I decide to.
Last edited:
