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power-on circuitry? also couple cmoy questions - Page 2

post #16 of 26
9/9/10 at 10:57pm
Thread Starter 

well that was fast, already got it. i guess 7.50 for one day shipping isnt too bad :o

 

still wondering about the opamps (would the ones used for the l/r channels in a ppa be fine in a cmoy too). here's a list of what i have:

 

AD797AN, AD8065AR, AD823AN, AD8066AR, AD8397ARZ, AD744BQ,  AD8610BRZ, AD825AR, AD843BQ, AD829AQ, AD8620BR, LM4562NA, OPA637AP, OPA627AP. iirc some of these were options for only the ground channel of the ppa though.

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post #17 of 26
9/12/10 at 2:27am

Yeah, I saw their shipping. Bleh. Still, you have to keep in mind that they aren't exactly targeting hobbyists. For the op-amps, you might start by checking them against this list. It's a good starting point at least.

 

I was fiddling around on the Jameco catalog page and this came up:

 

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_1953680_-1?CID=PDF

 

It looks to be a center-negative version of the above power supply for a buck cheaper. Unless I'm missing something. It's roughly 3AM, so, who knows.

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post #18 of 26
9/12/10 at 1:13pm
Thread Starter 

any of the opamps should work fine in the cmoy though right?

 

also apparently a few of the opamps i have are the tiny surface mount package rofl. i never really checked them all when i first got them, but they were free so who am i to complain :p plus i can just get an adapter.

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post #19 of 26
9/12/10 at 2:17pm

 

Quote:
 any of the opamps should work fine in the cmoy though right?

 

There are a couple of them that will not work in a CMoy.

The AD8397 is an example but that is the preferred op-amp for the left and right channels in a Mini3 so....

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post #20 of 26
9/16/10 at 1:30am
Thread Starter 

since i'm lazy, i've narrowed it down to two opamps since these are the only two dip-8 dual opamps i have out of my random collection: lm4562, ad823. any direction on where to go between these two? if not, im gonna just go with the 4562 since it's a bigger number and bigger means better right :p

 

also, if you havent seen my other thread about controlling an led with the volume control and may be able to answer a couple questions, a look here http://www.head-fi.org/forum/thread/512714/volume-controlled-led would be appreciated :)

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post #21 of 26
9/30/10 at 11:33pm
Thread Starter 

hmm, so putting it in series (+v -> resistor -> capacitor -> led -> ground) makes the led fade to nothing when the power turns on, it starts full power and fades out. i was going for the opposite effect D:

 

through various ways of putting the capacitor with the led/resistors, the closest i've come is getting the led to fade out after cutting power, i havent found a way to make it fade in when you turn on power. can anyone point out what im doing wrong? frown.gif

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post #22 of 26
10/1/10 at 11:16am
Thread Starter 

at this point i figure i actually want an inductor, not a capacitor in there.

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post #23 of 26
10/1/10 at 12:03pm

Place the capacitor in parallel with the LED to ground.

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post #24 of 26
10/1/10 at 1:06pm
Thread Starter 

hm, i thought i tried that. it might also be that i need a larger capacitor there. we'll see tongue.gif thanks.

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post #25 of 26
10/3/10 at 4:03am
Thread Starter 

ya ended up needing a much larger capacitor to get any noticable fade-in D:

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post #26 of 26
10/3/10 at 5:20am

There is some formulas on this page that may help:

 

RC Time Constant

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