jeffosborne
Enlightened
This was a project that kept me busy for several months. And satisfied my desire to have a very bright portable light! Hydra-2 is a fan-cooled light I designed and built from scratch. It is very similar to the original Hydra light I built last summer:
http://www.candlepowerforums.com/vb/showthread.php?t=170249
The first Hydra has served me well, but I wanted a smaller, brighter light with pushbutton level controls instead of the toggle switches. The 2 pushbuttons on top of Hydra-2 cycle through low, medium, high, and off, with separate controls for the front light and the bottom navigation light. It weighs 1.3 pounds, and is 8.4" long. The head is all aluminum, and the tube is 1.5" schedule-40 PVC pipe with a textured spray paint finish.
I had saved 4 Rebel cool-white100-lumen LEDs from before the recall for this light, and they are driven at 800ma on high mode, for 800 total lumens from the 4 front emitters. With 450 lumens max from the navigation light, it has a total output of 1,250 lumens! It can produce that level for one hour with it's three 18650 Li-ion batteries. Or both lights on medium for 3 hours, or both lights on low for 16.6 hours. Near to the push buttons on top of the light, the yellow indicator LED glows when the fan is on. The center red LED glows when the light has turned itself off because the battery voltage is less than 8.5 volts. And the red LED on the right glows when the light has turned itself off because the LED heat sink temperature has exceeded 200 degrees. Both red LEDs light when the light has turned itself off because the battery compartment is above 140 degrees. A quad comparator IC and thermistors accomplish most of these safety functions. When the LED heat sink reaches 120 degrees and the fan comes on, it draws air in through the 4 corners where the head and tube meet. Air is discharged through a vent on the bottom of the light. It usually takes 5 or 6 minutes on high before the fan comes on. The thin, 5 volt, 40mm fan draws only 40ma!
The 1/8" thick aluminum tail plate covers two battery charging jacks underneath.
Here is the bottom-side view, where the navigation light resides. These 3 neutral-white LEDs output a smooth flood of light. I did not have enough of the 100 lumen per watt cool-white LEDs, so I used the brightest Rebels I had for the navigation light, 80-lumen neutral whites. 450 lumens total from these 3 LEDs at 800ma. They are covered with a 1/16" thick lexan panel. Directly under them is the exhaust port for the cooling fan. It is covered with a fine aluminum screen to help it to be splash proof, and keep debris out.
Here's a view of the front emitters with their 20mm IMS reflectors. The white blob in the center of the reflectors is artic alumina holding a thermistor. It is wired to the comparator IC that turns on the fan. A polycarbonate sheet .1" thick covers the front emitters.
Here are some specs:
Front light (four emitters wired as 2 pairs of 2 in series)
low 100ma 80 lumens 25 hour
medium 580ma 400 lumens 4.5 hour
high 1600ma 800 lumens 1.5 hour
off to allow for navigation light only
Navigation light (three emitters wired in series)
low 50ma 45 lumens 50 hour
medium 290ma 210 lumens 9 hour
high 800ma 450 lumens 3 hour
off to allow for front light only
Beside being really bright, the long life and high efficiency of the low and medium modes were important design goals. Performing as a spot light or area light, or both, makes this light a very flexible tool. The neutral-white flood light is great for photography! Here are some highlights from the construction:
The first Hydra started with a Penium-2 CPU heat sink that was 2x2x.75" which was kind of large but needed, even with a cooling fan, because it was surrounded by plexiglass, not a great heat conductor. For Hydra-2 I chose a smaller heat sink, from an old 486 CPU, that is 1.75x1.75x.5" and enclosed it with aluminum, a very good heat conductor. Most important aspect for the 486 heat sink: the four IMS 20mm reflectors fit on top, with a little wiggle room, just a little. Quarter-inch aluminum side pieces are thick enough to allow me to drill and tap holes for #4-40 screws, which support the other pieces of the head, which are 1/8" aluminum. Let's let the enclosure head radiate some heat.
Here's the front Rebel emitters just after they were glued into place with arctic alumina epoxy. The thermistor in the middle is a 50K ohm glass enclosed part, bought from DigiKey.
Every good custom-build post needs a careful look down the reflectors at the emitters, in all their waffle-looking golden glory. I had to file away some material at the base of the reflectors to allow for the exit of the connecting wires. Well-mixed 5 minute epoxy holds these very lightweight reflectors to the heat sink. As the epoxy dried, I made small adjustments to center the emitters as best I could. 24 gauge wire was used for the short run between the emitters and the regulator mosfets.
Working with PVC pipe can be fun. It is easy to tool, and responds well to filing. The tube fits 5/8" up inside the head, and was slightly larger than the 1.75" heat sink. After filing, I used a very fine steel wool over the entire surface of the tube. That gave it a smooth finish and prepped it nicely for painting.
The paint is Rust-Oleum's 'hammered' texture spray paint. It needed two coats.
The battery pack uses three 2500mah LG cells, and a protection circuit board, item# LI-PCB-14V4 from batteryjunction.com, $9.95. It is a 10.8 volt nominal pack, and includes a 168 degree thermal cut off. The manufacturer specs the battery up to 140 degrees, so 168 is right out. The round lexan panel holds a coaxial serial charging jack, and a 4-pin balance charging jack. A 5mm fuse holder is epoxyed to the panel as well. I use a 4 amp fuse. 2 spare 4 amp fuses are wrapped in plastic and tucked between the fuse holder and the serial charging jack.
Here is the basic regulator. There are three of these mounted to the inside walls just behind the cooling fan. One regulator drives the navigation light, and two regulators drive the 4 front LEDs as two pairs. The mosfet and small signal transistor on the left are the regulator (hence the tell-tale white arctic alumina), with a 1/8 watt, 10 ohm resistor as the 'sense' component; it sets the regulator to 50ma. When a level button is pushed, a counter IC pin goes high that turns on one of the two mosfets on the right, which adds a 2.4 ohm or .68 ohm 2-watt resistor to the sense component. This raises the output current to 290 or 800ma. These Fairchild mosfets have a very low on resistance, and are 85 cents each at Future Electronics: FQP50N06.
With the circuits all removed, it looks like a lot of wire, but it is manageable. The PVC tube is roomy, and really is a good feel in the hand. The textured paint offers some grip, as well.
Here is a close up of the controller PCB – the two IC's on the right are the 4017 counters that take the pushbutton presses and sequentially raises output pins high, up to 10 steps. I needed only 4 steps (off, low, med, and high) so I attached the fifth output pin to the RESET pin and viola – a 4-step sequencer. The counter's output pins are connected directly to mosfet gates for the brightness level controls. The IC on the left is an LM239 quad comparator. Next to it is a LM336 2.5 volt precision reference diode, used as a stable voltage reference for the comparator. A small 5 volt regulator drives the cooling fan, when it comes on. The one blue 20K potentiometer adjusts for the 8.5 volt detection, which powers down the light when the battery drops too low. The battery pack's protection PCB from batterjunction.com would turn off the circuit at 7.5 volts, too low for best practices. This PCB resides in the tube, underneath the on-off rocker switch.
Forum member glockboy built a light a while back that inspired my efforts here, his 10-Cree Makita light. My hat is off to him and the many other great innovators here on the forum!
Hey, I will have some beam shot photos for you ASAP…
Jeff O.
http://www.candlepowerforums.com/vb/showthread.php?t=170249
The first Hydra has served me well, but I wanted a smaller, brighter light with pushbutton level controls instead of the toggle switches. The 2 pushbuttons on top of Hydra-2 cycle through low, medium, high, and off, with separate controls for the front light and the bottom navigation light. It weighs 1.3 pounds, and is 8.4" long. The head is all aluminum, and the tube is 1.5" schedule-40 PVC pipe with a textured spray paint finish.
I had saved 4 Rebel cool-white100-lumen LEDs from before the recall for this light, and they are driven at 800ma on high mode, for 800 total lumens from the 4 front emitters. With 450 lumens max from the navigation light, it has a total output of 1,250 lumens! It can produce that level for one hour with it's three 18650 Li-ion batteries. Or both lights on medium for 3 hours, or both lights on low for 16.6 hours. Near to the push buttons on top of the light, the yellow indicator LED glows when the fan is on. The center red LED glows when the light has turned itself off because the battery voltage is less than 8.5 volts. And the red LED on the right glows when the light has turned itself off because the LED heat sink temperature has exceeded 200 degrees. Both red LEDs light when the light has turned itself off because the battery compartment is above 140 degrees. A quad comparator IC and thermistors accomplish most of these safety functions. When the LED heat sink reaches 120 degrees and the fan comes on, it draws air in through the 4 corners where the head and tube meet. Air is discharged through a vent on the bottom of the light. It usually takes 5 or 6 minutes on high before the fan comes on. The thin, 5 volt, 40mm fan draws only 40ma!
The 1/8" thick aluminum tail plate covers two battery charging jacks underneath.
Here is the bottom-side view, where the navigation light resides. These 3 neutral-white LEDs output a smooth flood of light. I did not have enough of the 100 lumen per watt cool-white LEDs, so I used the brightest Rebels I had for the navigation light, 80-lumen neutral whites. 450 lumens total from these 3 LEDs at 800ma. They are covered with a 1/16" thick lexan panel. Directly under them is the exhaust port for the cooling fan. It is covered with a fine aluminum screen to help it to be splash proof, and keep debris out.
Here's a view of the front emitters with their 20mm IMS reflectors. The white blob in the center of the reflectors is artic alumina holding a thermistor. It is wired to the comparator IC that turns on the fan. A polycarbonate sheet .1" thick covers the front emitters.
Here are some specs:
Front light (four emitters wired as 2 pairs of 2 in series)
low 100ma 80 lumens 25 hour
medium 580ma 400 lumens 4.5 hour
high 1600ma 800 lumens 1.5 hour
off to allow for navigation light only
Navigation light (three emitters wired in series)
low 50ma 45 lumens 50 hour
medium 290ma 210 lumens 9 hour
high 800ma 450 lumens 3 hour
off to allow for front light only
Beside being really bright, the long life and high efficiency of the low and medium modes were important design goals. Performing as a spot light or area light, or both, makes this light a very flexible tool. The neutral-white flood light is great for photography! Here are some highlights from the construction:
The first Hydra started with a Penium-2 CPU heat sink that was 2x2x.75" which was kind of large but needed, even with a cooling fan, because it was surrounded by plexiglass, not a great heat conductor. For Hydra-2 I chose a smaller heat sink, from an old 486 CPU, that is 1.75x1.75x.5" and enclosed it with aluminum, a very good heat conductor. Most important aspect for the 486 heat sink: the four IMS 20mm reflectors fit on top, with a little wiggle room, just a little. Quarter-inch aluminum side pieces are thick enough to allow me to drill and tap holes for #4-40 screws, which support the other pieces of the head, which are 1/8" aluminum. Let's let the enclosure head radiate some heat.
Here's the front Rebel emitters just after they were glued into place with arctic alumina epoxy. The thermistor in the middle is a 50K ohm glass enclosed part, bought from DigiKey.
Every good custom-build post needs a careful look down the reflectors at the emitters, in all their waffle-looking golden glory. I had to file away some material at the base of the reflectors to allow for the exit of the connecting wires. Well-mixed 5 minute epoxy holds these very lightweight reflectors to the heat sink. As the epoxy dried, I made small adjustments to center the emitters as best I could. 24 gauge wire was used for the short run between the emitters and the regulator mosfets.
Working with PVC pipe can be fun. It is easy to tool, and responds well to filing. The tube fits 5/8" up inside the head, and was slightly larger than the 1.75" heat sink. After filing, I used a very fine steel wool over the entire surface of the tube. That gave it a smooth finish and prepped it nicely for painting.
The paint is Rust-Oleum's 'hammered' texture spray paint. It needed two coats.
The battery pack uses three 2500mah LG cells, and a protection circuit board, item# LI-PCB-14V4 from batteryjunction.com, $9.95. It is a 10.8 volt nominal pack, and includes a 168 degree thermal cut off. The manufacturer specs the battery up to 140 degrees, so 168 is right out. The round lexan panel holds a coaxial serial charging jack, and a 4-pin balance charging jack. A 5mm fuse holder is epoxyed to the panel as well. I use a 4 amp fuse. 2 spare 4 amp fuses are wrapped in plastic and tucked between the fuse holder and the serial charging jack.
Here is the basic regulator. There are three of these mounted to the inside walls just behind the cooling fan. One regulator drives the navigation light, and two regulators drive the 4 front LEDs as two pairs. The mosfet and small signal transistor on the left are the regulator (hence the tell-tale white arctic alumina), with a 1/8 watt, 10 ohm resistor as the 'sense' component; it sets the regulator to 50ma. When a level button is pushed, a counter IC pin goes high that turns on one of the two mosfets on the right, which adds a 2.4 ohm or .68 ohm 2-watt resistor to the sense component. This raises the output current to 290 or 800ma. These Fairchild mosfets have a very low on resistance, and are 85 cents each at Future Electronics: FQP50N06.
With the circuits all removed, it looks like a lot of wire, but it is manageable. The PVC tube is roomy, and really is a good feel in the hand. The textured paint offers some grip, as well.
Here is a close up of the controller PCB – the two IC's on the right are the 4017 counters that take the pushbutton presses and sequentially raises output pins high, up to 10 steps. I needed only 4 steps (off, low, med, and high) so I attached the fifth output pin to the RESET pin and viola – a 4-step sequencer. The counter's output pins are connected directly to mosfet gates for the brightness level controls. The IC on the left is an LM239 quad comparator. Next to it is a LM336 2.5 volt precision reference diode, used as a stable voltage reference for the comparator. A small 5 volt regulator drives the cooling fan, when it comes on. The one blue 20K potentiometer adjusts for the 8.5 volt detection, which powers down the light when the battery drops too low. The battery pack's protection PCB from batterjunction.com would turn off the circuit at 7.5 volts, too low for best practices. This PCB resides in the tube, underneath the on-off rocker switch.
Forum member glockboy built a light a while back that inspired my efforts here, his 10-Cree Makita light. My hat is off to him and the many other great innovators here on the forum!
Hey, I will have some beam shot photos for you ASAP…
Jeff O.
Last edited:
:thumbsup: Crazy! :naughty:
