GD 1000 resistor

About ordering the GD1000? where do I get the resistor values for single cell 17670, on ssc p4 driven at 3.8v? and do I solder them on or can I get them installed for me?

thank you

jbieszke said:

About ordering the GD1000? where do I get the resistor values for single cell 17670, on ssc p4 driven at 3.8v? and do I solder them on or can I get them installed for me?

thank you

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Are you referring to the resistors on the GD converter board? If your looking to purchase a GD1000, you can buy it complete from the shoppe here: http://theledguy.chainreactionweb.com/product_info.php?products_id=1107

If you'd like to change the output current to something other than 0.5 A or 1.0 A, you need to use their resistor calculator and buy the blank GD board. http://theledguy.chainreactionweb.com/product_info.php?products_id=961 You can have them solder them on for $3.00

cheers!

I guess that I had asked the wrong question. I was wondering how to set the vout to 3.8v, or maybe I dont even need to worry about that. Please help me if I am incorrect. li-ion battery = 4.2v + GD1000 + res1 .10 res2 .10 = 1000ma 5.0v + sscp4 (input 3.8v) how do I get the GD1000 to put out 3.8 vs. 5.0?

thanks

I think you might be confused as to what buck/boost constant current regulators do. They take any input from their range, and output some voltage within their output range that gets the output device to pull a set current. Having buck and boost allows the power source to be around the same voltage as the LED itself (raise or lower the voltage, as needed), which most Lithium chemistries are.

So, for the GD1000, if you buy it as a GD1000, then you need to solder it to the LED and power source. It will then give you 1A output to the LED, at whatever voltage that specific LED needs to pull 1A. It may not be 3.8V.

thank you cerbie you answered my question. I just wnat to make sure I have this right. even if the driver vout is rated at a higher level, the led wont be damaged because it only takes what it needs? do I have it correct?

Yes (note: as it comes to real details, I have not yet used a GD). Depending on the driver, there could be damage if it needs to push out more than 5.4V, or if you hook it up to higher than 5.4V input.

I wouldn't say it will take what it needs, as much as say it will take what it can get. But, what it wants to take (Amperes) does not match up perfectly with what you can measure to give it (Voltage).

LEDs do not have Vf all that close to each other, even in the same batch. One may push out 100 lumens at 3.6V, one may need 3.8V. But, they will be much closer together when it comes to current. One at 1000ma will put about the same amount out as another of the same bin at 1000ma. If you just run them by voltage, the outputs will be wildly different.

cerbie, I believe that you answered my question perfectly

thanks again
Jeff

heres one for you cerbie, what drivers have you used? the GD1000 is rated at 85-93% efficient and has a small .55 mcpcb