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Gear / Technical Help => Remote Power => Topic started by: aberg on December 02, 2005, 01:26:24 AM
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Does anyone know the best way of building a VRbox to take any DC input voltage and regulate down to 3v for an R-1, say??
I wanna run my mp2 and r1 off the same 9v walmart battery.
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http://www.tracopower.com/products/index.htm
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I used a LM317T in my box to drop the voltage for the jb3 Andrew. Here's how I understand it.
You can use it to do the same for the Edirol R1, you just need to use different resistor values.
Anyways, to figure out what resistors you need to use, you use the following formula:
"Vout=1.25(1+R2/R1). R1 is fixed. so, various Vout can be achieved by adjusting R2."
R1 must equal 150 ohm
R2 = X
Vout = 3v
Solve for X.
Looking at what's commonly available (Radio Shack Stock) R2 can equal 220 ohm. That'll give you (if my math is correct) a voltage of 3.08 Volts, which should be within the tolerances of the R1 (check the manual first, though) I would be concerned about the heat built up in the box though, as the bigger drop in voltage you get, the hotter it gets (or so I've read.) Anyways, hope this helps. Note: I'm not an electrician, and I wrote this at 1:30 am. Follow these directions at your own risk!
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quit bad idia to split the voltage with resistors even it works
invest at least in voltage regulator 7503 or similar and connect it parallel to the battery out
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quit bad idia to split the voltage with resistors even it works
invest at least in voltage regulator 7503 or similar and connect it parallel to the battery out
Why do you say this? The plan uses a voltage regulator (LM317T) My idea is based off similar boxes used to drop voltages to 5v for their jb3's (check out the jb3 power thread) which all use the LM317T voltage regulator. I've been using mine for 6 months with absolutely no problems to power a jb3. The only difference is, here, we're dropping down to 3 volts instead of 5v.
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my bad , i thought you like divide the voltage with resistors ,
yes it can work , but why work hard if you can buy one with in 9-18 /out 3 straight ahead :-)
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I'd go w/ the LT1086CT-3.3. I am sure 3.3V is within the acceptable voltage range. If 2.85 is better go w/ the LT1086CT-2.85. Rated for 1.5amps. Very simple circuit to build into a VR box. This is the T0-220 package. I prefer the surface mount ones but they are not for the weary.
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Thanks for all the advice here guys. I will likely build one of these once festival season hits. For now, I'm going to rely on internals.