Thanks Rob for all the Videos. Your tutorials help inspire my 10 year old son to convince me to help him build two sabers, which in turn has lead to him being accepted into a STEM based education program within his school district. Basically learning all aspects of schooling through the practice of product design and development methodology.
For red Cree LED: R=(4v- 2.6v) / 1A = 1.4 Ohms. TCSS doesn't sell a 1.4 ohm resistor, and the 1.2 ohm resistors are out of stock. Will the 1.5 ohm resistor affect brightness significantly?
I have three seperateled led colours Green Cree Part# XPEBGR-L1-0000-00F01 122 Minimum Luminous Flux @ 350mA Forward Voltage @1000mA = 3.7v Deep Red Cree Part# XPEBPR-L1-0000-00D01 450 Radiant Flux @ 350mA Forward Voltage @1000mA = 2.42v Cyan Cree Part# XPEBBL-L1-0000-00301 45.7 Minimum Luminous Flux @ 350mA Forward Voltage @1000mA = 3.4v so do I need to get a resistor for each or add them together? And will a 4(r) v battery be enough
A separate resistor for each parallel LED is good practice. Using 1 resistor for multiple LEDs in parallel, presuming they were matched to begin with, is when one LED gets hotter than the others it's forward voltage drops and it will draw a larger portion of the supplied current. Which can lead to runaway as the hot diode pulls most of the current. If the LEDs are different colors, a separate resistor is definitely required.
Hey Rob Petkau, I have a question a lot of people are telling me that you really dont need a resister on Green, Blue, or White. If you use the resister on those specific colors it will take away from the brightness. I just wanted to hear from you and see if it is true or not.
Without a resistor - and a full battery it will be overdriving the LED. A little brighter, and shorter life for the LED - your call. Also - if using a sound board it can cause fluctuations that negatively affect the sound boards performance.
+Rob Petkau thank you for your response. Yeah when I was told that, it really didn't make sense to me because if I'm going to run it through the soundboard I really don't want to cause any issues with the board and also overheating or burning out the LED. So thank you again, I will be using a resister for my install.
Nice video, the formula is self explanatory, but say you run greens/whites 1amp without a resistor (3.7/3.5 Vf) with a single 3.7V battery setup will you burn the LED out? Would it be brighter?
Great video. But this helps if you are only hooking up one part to a battery. I haven't seen a video or tutorial on where to put the resistor(s) when you have to hook up your sound card, LED button, speaker, blade LED and any accent LED's. Do you calculate total Vf - total amps for one resistor, or do you use a resistor between each piece in series? If so, how do you calculate the resistor? Does anyone know a good tutorial or have an answer??
Probably the same silly question, but if i want to tone down an led with a resistor because my led won't mix well with another (read washes out), which parameters would I have to use? I think the nominal Vf and the desired current? Also would I still need the protection resistor after that?
I'm sorry for my vague question. What I was trying to say is, I have a blue led and a red led to make purple, but the blue washes out my red completely. I wanted to calculate the resistor to cut the current through the blue led, but I was uncertain of which parameters to use. I think the nominal Vf and the desired mA I want to suppress, but I will just have to try different values. Thank you for your time
I have a deep red tri cree. at 4v ohm law says I need 2 ohm resistors . but at tcss they only sell 2 ohm 1 watt resistors. you recommend 3 or 5 watt. what would happen if I bought the next size up resistor at 2.2 ohm 5 watt
+Gavin Orth FYI...LEDs will vary voltage and current specs based on color and other attributes...not based on wattage. It does not matter that it's a 12W LED. It's meaningless. You need the specs for the specific LED you have.
+Gavin Orth Glad you're an EE major. I have a BSEE, MBA, and 38 years in engineering and IT, general manager director at a very large corp. So waving a flag saying I'm an EE major means little to me. Let's set aside our credentials, as I agree with what you are trying to say, SF are idiots with that 12W led stuff. A higher wattage LED does not equal a brighter LED, its just a marketing ploy they use to sell to an uneducated marketplace. Example, a 60W incandescent light bulb is not brighter than a 20W LED bulb. I agree with you, get a TriCree, I own several myself, in addition to some very bright LED string blades I have. My Makoto V4 LED string is by far the brightest blade I own, brighter than the two Makoto V3's, the three TriCree's, the TricCree RGB, and the one SF 12W+ I own.
+Gavin Orth Since you are an EE student you may want to note the error in your statement. The 12w LED are in fact CREE based LEDs. They are 4 Cree XB-D mounted to a custom star (placed touching which reduces cooling and light output due to said poor cooling) instead of 3 of the newer and brighter XP-E or XP-E2 mounted to the SinkPad II that are sold through other vendors. If you want to know why they are labeled as 12W, it stems from the way CREE markets the XB-Ds as 3W LEDs. So piggie backing on CREEs datasheets SF markets them as 6W and 12W to match. Also I personally know 2 of the EEs that develope the CREE LEDs and have I have designed lighting solutions for them as well so I kinda second Robert's comments
Hi Rob, I'm having some trouble here and I guess I'm just not looking in the right places. I can see that my LED has a max current of 1000 mA, but the max forward voltage specified (3 Vf) is only rated at 350 mA. Is there a ratio I need to use to figure out the max Vf or something?
If you haven't already, check out ledsupply . com and go to the LED product page in question. If your LED is there, a list will be at the bottom where it should show max forward voltage at 350 mA, followed by Vf at 1000 mA.
I still dont get it............ NAH!!!!! just kidding. This video helped me a lot, thank you for explaining OHM's law!!! It is really easy to calculate for the right resister needed for your saber.
Hey Rob. Thanks for all your very helpful vids. Ive learned so much from you. Youre awesome! Im having an issue and cant find the help i need. Im doing a project and i cant wrap my head around my problem. I need to run 9-10 watts to my leds. (cree xp-e2 tripple up) At a maximum of 1000ma. Im using a 12v battery pack at 2000ma. But the circut board thats in the circut can only run at max of 4.5v. I cant figure out how to run the proper resisters to both the board and leds. I tried running it at 4.5v..with a transistor to boost the leds. Not working. I tried 9v...the leds work but the board doesnt. Should i be running main power with 9v instead of 12v? Please help. You may email me if its preferred. Louissdumoulin@gmail.com. thanks.
You just saved me a lot of trial & error guesswork, sir. Many thanks.
Thanks Rob for all the Videos. Your tutorials help inspire my 10 year old son to convince me to help him build two sabers, which in turn has lead to him being accepted into a STEM based education program within his school district. Basically learning all aspects of schooling through the practice of product design and development methodology.
+Josh Leedle That's so cool!
For the Resistance!
Ohm my gosh, thank you so much for this video!
So, I am a little confused on one thing, are the Max amps labeled as the Maximum luminous flux on the sheets seen on the custom saber shop?
actually that helps loads as i didn't realise your best to round up to start with !
For red Cree LED: R=(4v- 2.6v) / 1A = 1.4 Ohms. TCSS doesn't sell a 1.4 ohm resistor, and the 1.2 ohm resistors are out of stock. Will the 1.5 ohm resistor affect brightness significantly?
Not significantly - that would be a good choice IMHO
As always, thank you for the vid Rob!
Thank you for sharing your knowledge. You Rock dude !
I have three seperateled led colours Green Cree Part# XPEBGR-L1-0000-00F01
122 Minimum Luminous Flux @ 350mA
Forward Voltage @1000mA = 3.7v
Deep Red Cree Part# XPEBPR-L1-0000-00D01
450 Radiant Flux @ 350mA
Forward Voltage @1000mA = 2.42v
Cyan Cree Part# XPEBBL-L1-0000-00301
45.7 Minimum Luminous Flux @ 350mA
Forward Voltage @1000mA = 3.4v
so do I need to get a resistor for each or add them together?
And will a 4(r) v battery be enough
Rob that video does help thanks a bunch you are a great help and inspiration.
Man, I wish I had of stayed in college. Now I want to learn this stuff! I had no interest at 17-18 years old, now I wish I had of just done it.
My plan is to wire a simple saber without sound with a tri cree. Do I need a resistor for each LED in the cree?
A separate resistor for each parallel LED is good practice. Using 1 resistor for multiple LEDs in parallel, presuming they were matched to begin with, is when one LED gets hotter than the others it's forward voltage drops and it will draw a larger portion of the supplied current. Which can lead to runaway as the hot diode pulls most of the current.
If the LEDs are different colors, a separate resistor is definitely required.
Hey Rob Petkau, I have a question a lot of people are telling me that you really dont need a resister on Green, Blue, or White. If you use the resister on those specific colors it will take away from the brightness. I just wanted to hear from you and see if it is true or not.
Without a resistor - and a full battery it will be overdriving the LED. A little brighter, and shorter life for the LED - your call.
Also - if using a sound board it can cause fluctuations that negatively affect the sound boards performance.
+Rob Petkau thank you for your response. Yeah when I was told that, it really didn't make sense to me because if I'm going to run it through the soundboard I really don't want to cause any issues with the board and also overheating or burning out the LED. So thank you again, I will be using a resister for my install.
Nice video, the formula is self explanatory, but say you run greens/whites 1amp without a resistor (3.7/3.5 Vf) with a single 3.7V battery setup will you burn the LED out? Would it be brighter?
In a nutshell, it might slightly shorten the LED lifespan. Would be slightly brighter, but would interfere with the operation of a sound card.
Great description on ohms...but FJKs post on watts make my head spin.
Liking the new production value in your videos. What are you using for editing software these days, Rob?
+Saber Baron Thanks. I use Cyberlink Power Director 13. The TCSS intro was done by someone else - I just added sound.
Great video. But this helps if you are only hooking up one part to a battery. I haven't seen a video or tutorial on where to put the resistor(s) when you have to hook up your sound card, LED button, speaker, blade LED and any accent LED's. Do you calculate total Vf - total amps for one resistor, or do you use a resistor between each piece in series? If so, how do you calculate the resistor? Does anyone know a good tutorial or have an answer??
Probably the same silly question, but if i want to tone down an led with a resistor because my led won't mix well with another (read washes out), which parameters would I have to use? I think the nominal Vf and the desired current? Also would I still need the protection resistor after that?
I'm not certain what you mean. If you have a resistor on your red and it's still too bright. Try a resister with a slightly higher value in Ohms.
I'm sorry for my vague question. What I was trying to say is, I have a blue led and a red led to make purple, but the blue washes out my red completely. I wanted to calculate the resistor to cut the current through the blue led, but I was uncertain of which parameters to use. I think the nominal Vf and the desired mA I want to suppress, but I will just have to try different values. Thank you for your time
Yes - experimenting is the best.
I have a deep red tri cree. at 4v ohm law says I need 2 ohm resistors . but at tcss they only sell 2 ohm 1 watt resistors. you recommend 3 or 5 watt. what would happen if I bought the next size up resistor at 2.2 ohm 5 watt
That would work very well
Rob Petkau thank you :-) all your info and videos are very much appreciated. I've learnt a lot by watching them
You are most welcome!
what about 13.8 volts from a 12 volt supply for a train set
when will you have power coating again
when are you going to restock mhs emitters?
New shop, new machines, parts are being restocked each week. Thanks for your patience.
What about a 12w led?
the saberforge 12w are usually pre-resistored for a 3.7v battery but I would recommend a tri cree
Seriously, did you even watch the video? Whether it's a 12W or a1200W LED, the laws of physics don't change. Follow the math he shows for your LED.
+Gavin Orth FYI...LEDs will vary voltage and current specs based on color and other attributes...not based on wattage. It does not matter that it's a 12W LED. It's meaningless. You need the specs for the specific LED you have.
+Gavin Orth Glad you're an EE major. I have a BSEE, MBA, and 38 years in engineering and IT, general manager director at a very large corp. So waving a flag saying I'm an EE major means little to me.
Let's set aside our credentials, as I agree with what you are trying to say, SF are idiots with that 12W led stuff. A higher wattage LED does not equal a brighter LED, its just a marketing ploy they use to sell to an uneducated marketplace. Example, a 60W incandescent light bulb is not brighter than a 20W LED bulb.
I agree with you, get a TriCree, I own several myself, in addition to some very bright LED string blades I have. My Makoto V4 LED string is by far the brightest blade I own, brighter than the two Makoto V3's, the three TriCree's, the TricCree RGB, and the one SF 12W+ I own.
+Gavin Orth
Since you are an EE student you may want to note the error in your statement. The 12w LED are in fact CREE based LEDs. They are 4 Cree XB-D mounted to a custom star (placed touching which reduces cooling and light output due to said poor cooling) instead of 3 of the newer and brighter XP-E or XP-E2 mounted to the SinkPad II that are sold through other vendors.
If you want to know why they are labeled as 12W, it stems from the way CREE markets the XB-Ds as 3W LEDs. So piggie backing on CREEs datasheets SF markets them as 6W and 12W to match.
Also I personally know 2 of the EEs that develope the CREE LEDs and have I have designed lighting solutions for them as well so I kinda second Robert's comments
can anyone help me please i want to use 4 AAA batterys and do I have to take the voltage of the four batterys or just one?
A 4*AA battery pack would have the batteries in series. So 4 times the voltage of a single battery.
This really helped thanks!
Hey, little tip guys. If using Deep Red leds, you might need to plan out your space a little more. The resistors for those can run large :)
Thanks brother..!! 👍
Somebody help this man find his resistor!
Hi Rob, I'm having some trouble here and I guess I'm just not looking in the right places. I can see that my LED has a max current of 1000 mA, but the max forward voltage specified (3 Vf) is only rated at 350 mA. Is there a ratio I need to use to figure out the max Vf or something?
If you haven't already, check out ledsupply . com and go to the LED product page in question. If your LED is there, a list will be at the bottom where it should show max forward voltage at 350 mA, followed by Vf at 1000 mA.
I still dont get it............ NAH!!!!! just kidding. This video helped me a lot, thank you for explaining OHM's law!!! It is really easy to calculate for the right resister needed for your saber.
that's a cunning shirt you have on there
Hey Rob. Thanks for all your very helpful vids. Ive learned so much from you. Youre awesome! Im having an issue and cant find the help i need.
Im doing a project and i cant wrap my head around my problem. I need to run 9-10 watts to my leds. (cree xp-e2 tripple up) At a maximum of 1000ma. Im using a 12v battery pack at 2000ma. But the circut board thats in the circut can only run at max of 4.5v. I cant figure out how to run the proper resisters to both the board and leds. I tried running it at 4.5v..with a transistor to boost the leds. Not working. I tried 9v...the leds work but the board doesnt. Should i be running main power with 9v instead of 12v? Please help.
You may email me if its preferred.
Louissdumoulin@gmail.com. thanks.
Resistance is futile!