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Post by ben on Nov 12, 2014 10:52:21 GMT -6
Ok, so it was the 14k resistor that was bad. Now the voltages are where they should be, but man it was tough finding a 14k 1 watt resistor. Ended up using a 14k .6w from Digikey. Everything seems to be good, I just hope the resistor doesn't blow. I'll burn it in before I close it all up.
Thanks again for all the help, RG brethren!
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Post by svart on Nov 17, 2014 10:20:45 GMT -6
Ok, so it was the 14k resistor that was bad. Now the voltages are where they should be, but man it was tough finding a 14k 1 watt resistor. Ended up using a 14k .6w from Digikey. Everything seems to be good, I just hope the resistor doesn't blow. I'll burn it in before I close it all up. Thanks again for all the help, RG brethren! You can series up two 7K-ish 1/2W resistors or parallel up two 28K-ish 1/2W resistors. With resistors, series adds value and power. Parallel divides value but adds power rating. With two resistors of the same value in parallel, the value will be half the value of one of them. If they aren't the same value the equation for parallel resistors is R=R1xR2/(R1+R2) Or if you know one value of parallel resistor: R2=R1xRtotal/(R1-Rtotal) But in any case, the resistor power handling value still adds, so 1/2W + 1/2W is 1W, etc. in a situation like this with analog voltages, it doesn't necessarily need to be exactly 14K ohms either. It could be 14.1K or 13.8K, or something else within a couple %. |
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Post by ben on Nov 17, 2014 12:43:30 GMT -6
Ok, so it was the 14k resistor that was bad. Now the voltages are where they should be, but man it was tough finding a 14k 1 watt resistor. Ended up using a 14k .6w from Digikey. Everything seems to be good, I just hope the resistor doesn't blow. I'll burn it in before I close it all up. Thanks again for all the help, RG brethren! You can series up two 7K-ish 1/2W resistors or parallel up two 28K-ish 1/2W resistors. With resistors, series adds value and power. Parallel divides value but adds power rating. With two resistors of the same value in parallel, the value will be half the value of one of them. If they aren't the same value the equation for parallel resistors is R=R1xR2/(R1+R2) Or if you know one value of parallel resistor: R2=R1xRtotal/(R1-Rtotal) But in any case, the resistor power handling value still adds, so 1/2W + 1/2W is 1W, etc. in a situation like this with analog voltages, it doesn't necessarily need to be exactly 14K ohms either. It could be 14.1K or 13.8K, or something else within a couple %. Good info, thanks! I wish I had learned all of this years ago, it's actually a lot of fun. Making cables, I can do blindfolded, spun around and upside down, but throw a resistor or capacitor in there and it may as well be Hamlet in Greek. Better late than never. |
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