Gazoo
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What are you supplying the circuit with. If it is getting enough voltage the current should be ~400ma's regardless of the diode.
1.25/3 = 417ma's.
1.25/3 = 417ma's.
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Red Senkat diode not strong with 250ma?
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Gazoo said:[quote author=spinout059 link=1198336575/0#11 date=1198372065]w00t i got it to work!!! I dont know why I couldnt before....Will a driver make it burn better? BTW put black sharpie on my arm, now that was cool
Video coming soon!
I am glad you got it working but what's up with your signature? Don't you know you are supposed to already have goggles
[/quote]Not enough money for goggles atm :'( thats why I have my donation link!
Might be the batteries, although they measure 6.12 volts. AAs x 4.
As I tune EACH diode I install (starting with 20+ ohms), so far - it's been all good. When I switch to the Lion rechargables I'll probably get different results and different resistor values.
Dave
As I tune EACH diode I install (starting with 20+ ohms), so far - it's been all good. When I switch to the Lion rechargables I'll probably get different results and different resistor values.
Dave
Gazoo
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Sounds like the batteries are sagging..of course the Li-ions will solve the problem. Don't forget to turn your pot to the highest resistance when you switch over.. ;D Then re-adjust.
Yeah... I'm lazy. I always just start with high R and tune for current to the diode - I don't really even look at voltage... but I just did. Measuring 854 mA across my 3 ohm resistor, yielding 284mA to the diode. Measured the battery voltage under load - 5.73 and slowly dwindling.
Like I said - lazy. But the diodes burn wonderfully, only cook when I spike them accidentally in-circuit, and should last a long time as long as I never overdrive them. My philosophy is to KNOW the math, but only rely on measurements!
Dave
PS., I just poked a hole in a black CD case back from about 10 feet in 12 seconds with my saggy batteries!
Like I said - lazy. But the diodes burn wonderfully, only cook when I spike them accidentally in-circuit, and should last a long time as long as I never overdrive them. My philosophy is to KNOW the math, but only rely on measurements!
Dave
PS., I just poked a hole in a black CD case back from about 10 feet in 12 seconds with my saggy batteries!
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I could notice a differnce when my batteries started going below 6v, the regulator started dropping out and i couldnt light my fireworks at 4ft no more , only at 3ft ;D
...lazer... ;D ;D ;D
, only at 3ft ;D...lazer... ;D ;D ;D
That's the beauty of ohm's law - measure the voltage drop across the 3 ohm resistor, divide by 3 and you have the LD current - regardless of what the supply voltage is doing (to a point).
My "final" revision to the first project will include a current monitor that will watch the voltage drop across the fixed resistor, and a battery voltage monitor (both bar graphs). All in a tiny little package.
My "final" revision to the first project will include a current monitor that will watch the voltage drop across the fixed resistor, and a battery voltage monitor (both bar graphs). All in a tiny little package.
xanatos said:Yeah... I'm lazy. I always just start with high R and tune for current to the diode - I don't really even look at voltage... but I just did. Measuring 854 mA across my 3 ohm resistor, yielding 284mA to the diode. Measured the battery voltage under load - 5.73 and slowly dwindling.
Like I said - lazy. But the diodes burn wonderfully, only cook when I spike them accidentally in-circuit, and should last a long time as long as I never overdrive them. My philosophy is to KNOW the math, but only rely on measurements!
Dave
PS., I just poked a hole in a black CD case back from about 10 feet in 12 seconds with my saggy batteries!
I think you meant 854mV not 854mA
That being the case, your regulator is dropping out. You should always provide the LM317 with a high enough Vin to maintain 1.25Vsense. Gazoo keeps saying that using the LM317 with 6 NiMH cells is best, and I'm inclined to agree.
He's probably right. 854mV, yes. I know what I mean anyway! Just that I know that I'm looking to read current when I am reading the voltage drop, so I'm already thinking in terms of I and not V.
But as I said, unless i'm doing a burning demo for someone (like th 80000000 neices & nephews my wife has that I will see this Christmas), my only concern is that it burna enough without me risking cooking the diode. I'll be using fresh lithiums and re-tune the resistance before we leave to visit family I plan on giving the kids a good "cooking" demonstration. I like that I can burn through CD cases!
Dave
Just that I know that I'm looking to read current when I am reading the voltage drop, so I'm already thinking in terms of I and not V. But as I said, unless i'm doing a burning demo for someone (like th 80000000 neices & nephews my wife has that I will see this Christmas), my only concern is that it burna enough without me risking cooking the diode. I'll be using fresh lithiums and re-tune the resistance before we leave to visit family
I plan on giving the kids a good "cooking" demonstration. I like that I can burn through CD cases!Dave
xanatos said:
That's what I'm afraid of. Unless you remember to turn the pot to the max resistance every time you change batteries you'll risk the LD. The entire point of a regulator is to maintain a constant current regardless of input voltage or LD junction temperature. As it is now, you've limited the current to just over 400mA, but the current the LD actually sees is dependant on the input voltage.
That said, if it's working for you then go for it.
Gazoo
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xanatos said:
Yeah and isn't it funny that even though we know the math, we always measure to be sure.. ;D Well anyway, I think any kind of battery monitoring device is a very good idea especially when using li-ions. I will be looking forward to pics of your build. Sounds like it will look and be awesome with those bar graphs.
The prototype is using the cheapo Radio Shack "bricks" - stacked rectangular LEDs in a bar. Problem is that they're FAT. I'm using all surface mount components, and the entire circuit for the driver for the LD, the scanning circuitry, and the voltage monitoring COMBINED is about the same size as one of the 20 pin DIP LED Bargraph displays. I'm searching around for a MUCH more compact way of doing this - will probably have to go with discreet surface mount diffuse-lens LEDS - I found them on DigiKey, Jameco & Mouser.
I don't think I have posted any pics of the displays yet - you may be recalling some of the circuitry running in the background of my video of my first SenKat diode lighting matches. I had a scanning circuit running on the protoboard (indicating which input ports on an array I'm using were being sensed sequentially, but I digress).
I'll be posting pics soon - along with a library of surface mount component templates for use in making your own surface mount PC boards.
Best,
Dave
I don't think I have posted any pics of the displays yet - you may be recalling some of the circuitry running in the background of my video of my first SenKat diode lighting matches. I had a scanning circuit running on the protoboard (indicating which input ports on an array I'm using were being sensed sequentially, but I digress).
I'll be posting pics soon - along with a library of surface mount component templates for use in making your own surface mount PC boards.
Best,
Dave
