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Projects => Tech Help - Projects Page => Topic started by: thetrend77 on February 21, 2012, 06:12:38 PM

Title: Sea Urchin Resistor Question
Post by: thetrend77 on February 21, 2012, 06:12:38 PM
I'm in the process of making a Sea Urchin and I don't have a 33R resistor for R7. What would happen if I put three 10R's in series in its place? That would only be 30R, I know, but would that be close enough?

Also, I did something similar with the 360k resistor. I put two 180k's in series. That DOES work, right (sorry, noob question lol)?
Title: Re: Sea Urchin Resistor Question
Post by: irmcdermott on February 21, 2012, 06:15:06 PM
Quote from: thetrend77 on February 21, 2012, 06:12:38 PM
I'm in the process of making a Sea Urchin and I don't have a 33R resistor for R7. What would happen if I put three 10R's in series in its place?

You would have around ~30R resistance, depending on tolerance :)
Title: Re: Sea Urchin Resistor Question
Post by: thetrend77 on February 21, 2012, 06:15:45 PM
Yeah, I'm just wondering if that would be ok or if I actually need exactly 33 ohms.
Title: Re: Sea Urchin Resistor Question
Post by: irmcdermott on February 21, 2012, 06:24:54 PM
Quote from: thetrend77 on February 21, 2012, 06:15:45 PM
Yeah, I'm just wondering if that would be ok or if I actually need exactly 33 ohms.

I'd solder some wires to the PCB where that resistor is and connect it, with the resistors in series, to a breadboard and see what happens. If you measure a bunch of those 10R resistors and pick three that get the closest closest to 33R, you should be fine.
Title: Re: Sea Urchin Resistor Question
Post by: madbean on February 21, 2012, 06:40:29 PM
The value is not critical. It's just a little filtering for the PS. You can use whatever closest value you have, 22R, 47R, 100R will all work fine.
Title: Re: Sea Urchin Resistor Question
Post by: thetrend77 on February 21, 2012, 06:45:28 PM
Quote from: madbean on February 21, 2012, 06:40:29 PM
The value is not critical. It's just a little filtering for the PS. You can use whatever closest value you have, 22R, 47R, 100R will all work fine.

Great! Thanks, Brian!
Title: Re: Sea Urchin Resistor Question
Post by: jimmybjj on February 21, 2012, 06:58:24 PM
That resistor creates a high pass filter, attempting to subdue supply noise, right?