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- Dec 26, 2007
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So I was repairing a loose connection in one of my Dorcy Jr/Senkat mods last weekend, (thanks Kenom ;D see original construction here:http://www.laserpointerforums.com/forums/YaBB.pl?num=1181635652),and a long held curiosity got the best of me. I always add 5-ohms to the Dorcy Jr, (available here:http://stonetek.org/shop/index.php?main_page=product_info&cPath=69&products_id=201)when using the Senkat diodes, (Thanks SenKat- buy these here:http://stonetek.org/shop/index.php?main_page=product_info&cPath=65&products_id=180), to keep the current down to about 230-240mA, the only diode I have ever lost was a Dorcy with no added resistors, (350-400mA-lasted about 2-weeks though). I wondered...the stock board in the flashlight puts out a little over 5v-open circuit, from a 3v battery, but of course drops to the voltage of the diode when it is loaded..hmmm. I keep reading that the diode will take whatever voltage it wants, as long as there is enough, but the current must be limited, I have seen this to be true. So I added some wires to the board and plugged the leads into my breadboard, and started adding resistor combos between the flashlight circuit and a Bluray dummy-load, I use 4-green LEDs, 2 groups of 2 in series, and then paralleled together, (I also used 100ohm resistor with about the same results, just no gratifing-LED-light-up). I really like this dummy load, it seams to match the actual BR diode very well, thanks to whoever suggested this 
.
Well 33ohms first right?, the voltage across the diode was about right 4.6v-4.8v, and the current was about 4mA, as I remember, so I started changing the resistance, a pot would have been nice, but I didn't have any handy and I have never been able to install one in a Dorcy Jr. I finally settled on 22ohms+ 1ohm sense resistor giving me about 4.5v across the diode and 34 mA of current draw, seemed stable, so...I plugged in a BR diode, it lit!!!, about the same reading as with the dummy load- 4.51v across the diode and a "rock-steady" 34.4 mA draw, according to my "DIY Laser Power Meter-(Thanks Knimrod!!! see instructions here:http://www.laserpointerforums.com/forums/YaBB.pl?num=1200112201") the diode was putting out about 10mW. I let it run for about 10 mins with no heat-up, or change in current draw, (maybe 1mA over 10mins). I then tried it with a freshly charged 3.7v battery (batt.-measured 3.8v after “rest”), still with the 22ohm resistor in series with a 1-ohm resistor for current measurement, and the readings were 4.54v for the diode with a 36mA draw and putting out 12 mW, without the 1-ohm sense resistor, 38-mA draw, sound familiar?, this should be "worst-case".
Well that was enough for me, I tore into installing this set-up into a host, I had to leave out the "1-ohm sense resistor" because of space limitations, but the build went good, except for when I broke the neg. pin on my diode and thought I lost it forever, but I was able to resolder a new connection and move on. The results..in the final host, with just the 22ohm resistor added to the original circuit, I was reading 14mW output, I then replaced the acrylic Aixiz lens with a glass Aixiz lens, that upped my reading to about 16-17 mW, this is about what I see using a "DDL circuit with a 33-ohm resistor" (thanks Daedal!!! see the DDL circuit here:http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612).I have now been playing with this little guy for almost a week, and the output has not changed, my new favorite laser!!.
If anyone is interested, here are some measurements I read with the resistor combo, all of these were measured using "volts" across a 1-ohm sense resistor for the current draw:
Battery- 3v primary- DX-new which measured 2.8volt Lens- Aixiz acrylic
33ohm+1ohm in series= 27mA draw/4mW output
23.5 ohm (47R=47R in parallel)+1ohm resistor= 34 mA draw/8mW output
22 ohm+1ohm=34.4mA draw/10mW output
Battery- 3.7v Rechargeable- DX-Ultrafire which measured 3.8volts Lens- Aixiz acrylic
22 ohm+1ohm=36mA draw/12mW output (4.54 volts across the diode)
In conclusion, this seams to work great, and no 9-volt battery, yeah!! Is this a “constant-current circuit"?, I doubt it, but it is current limiting, and the BR diode draws so little that I do not think we have all of the thermal runaway issue that we would for a DVD diode. I have run this set-up for several 10-minute runs, with no fluctuation in the diode-output, I cannot measure current draw once installed in the host, but when still in the breadboard there was little or no drift in the current-output over a 10-minute run.
I have used many Senkat diodes in these set-ups, and soon will be trying a Phaser-diode in this host, (hopefully soon), and it is now known to work for Blurays as well, is there another host with such versatility?
Are all “boosting” flashlights set-up like this? Can we can just resistor-down to our desired current and go? I do not know, but I soon will (1xaaa BR host anyone?).
As always, these were my individual results, the resistors, host circuit, and BR diode all may be quite different for you,[highlight]”individual results may vary- experiment at your own risk”[/highlight] I will update if anything new happens as far as projected lifetime of this set-up, I expect it to last a long time, but who knows?. I hope you all enjoy!!
Thank you to Laser Pointer Forums!!!! 3-months ago I could not have done any of this. Now on to the optics
I hope you enjoy!,
Dark Horse
.Well 33ohms first right?, the voltage across the diode was about right 4.6v-4.8v, and the current was about 4mA, as I remember, so I started changing the resistance, a pot would have been nice, but I didn't have any handy and I have never been able to install one in a Dorcy Jr. I finally settled on 22ohms+ 1ohm sense resistor giving me about 4.5v across the diode and 34 mA of current draw, seemed stable, so...I plugged in a BR diode, it lit!!!, about the same reading as with the dummy load- 4.51v across the diode and a "rock-steady" 34.4 mA draw, according to my "DIY Laser Power Meter-(Thanks Knimrod!!! see instructions here:http://www.laserpointerforums.com/forums/YaBB.pl?num=1200112201") the diode was putting out about 10mW. I let it run for about 10 mins with no heat-up, or change in current draw, (maybe 1mA over 10mins). I then tried it with a freshly charged 3.7v battery (batt.-measured 3.8v after “rest”), still with the 22ohm resistor in series with a 1-ohm resistor for current measurement, and the readings were 4.54v for the diode with a 36mA draw and putting out 12 mW, without the 1-ohm sense resistor, 38-mA draw, sound familiar?, this should be "worst-case".
Well that was enough for me, I tore into installing this set-up into a host, I had to leave out the "1-ohm sense resistor" because of space limitations, but the build went good, except for when I broke the neg. pin on my diode and thought I lost it forever, but I was able to resolder a new connection and move on. The results..in the final host, with just the 22ohm resistor added to the original circuit, I was reading 14mW output, I then replaced the acrylic Aixiz lens with a glass Aixiz lens, that upped my reading to about 16-17 mW, this is about what I see using a "DDL circuit with a 33-ohm resistor" (thanks Daedal!!! see the DDL circuit here:http://www.laserpointerforums.com/forums/YaBB.pl?num=1185701612).I have now been playing with this little guy for almost a week, and the output has not changed, my new favorite laser!!.
If anyone is interested, here are some measurements I read with the resistor combo, all of these were measured using "volts" across a 1-ohm sense resistor for the current draw:
Battery- 3v primary- DX-new which measured 2.8volt Lens- Aixiz acrylic
33ohm+1ohm in series= 27mA draw/4mW output
23.5 ohm (47R=47R in parallel)+1ohm resistor= 34 mA draw/8mW output
22 ohm+1ohm=34.4mA draw/10mW output
Battery- 3.7v Rechargeable- DX-Ultrafire which measured 3.8volts Lens- Aixiz acrylic
22 ohm+1ohm=36mA draw/12mW output (4.54 volts across the diode)
In conclusion, this seams to work great, and no 9-volt battery, yeah!! Is this a “constant-current circuit"?, I doubt it, but it is current limiting, and the BR diode draws so little that I do not think we have all of the thermal runaway issue that we would for a DVD diode. I have run this set-up for several 10-minute runs, with no fluctuation in the diode-output, I cannot measure current draw once installed in the host, but when still in the breadboard there was little or no drift in the current-output over a 10-minute run.
I have used many Senkat diodes in these set-ups, and soon will be trying a Phaser-diode in this host, (hopefully soon), and it is now known to work for Blurays as well, is there another host with such versatility?
Are all “boosting” flashlights set-up like this? Can we can just resistor-down to our desired current and go? I do not know, but I soon will (1xaaa BR host anyone?).
As always, these were my individual results, the resistors, host circuit, and BR diode all may be quite different for you,[highlight]”individual results may vary- experiment at your own risk”[/highlight] I will update if anything new happens as far as projected lifetime of this set-up, I expect it to last a long time, but who knows?. I hope you all enjoy!!
Thank you to Laser Pointer Forums!!!! 3-months ago I could not have done any of this. Now on to the optics
I hope you enjoy!,
Dark Horse
