A Question about Resistor

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john101
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A Question about Resistor

Post by john101 » Mon Mar 18, 2013 11:18 am

I am glad that I have got my answer so quickly, yesterday I posted my question about usage about SD/mmc card.
Today I start to buy the components that I need.
I have found that the Resistor is hard to find in local electronics store.They told me the value(3.16K, 1.58K,806, 75)
is nonstandard value.
In my opinion, they can be replaced by some close value and according to the ratio I guessed?(3.16k=2*1.58k, 1.58k=806*2, 806=75*11,)
The value must be accurate as the schematic labeled? Because they are hard to buy.
If anyone can give some explain about this behind, that would be wonderful. (The books just tell me Abide by the proportion,but in reality , if we choose 316k, 158k, 80.6k, 7.5k, it still works? or some very little value, I guess this is related power.)


Thank you in advance.

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Kilo
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Re: A Question about Resistor

Post by Kilo » Mon Mar 18, 2013 11:30 am

Hi,

first: Where're you from? :)
The last digit of Pi is 7! I calculated this, as I counted to infinity yesterday!

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Kerby
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Re: A Question about Resistor

Post by Kerby » Mon Mar 18, 2013 2:01 pm

Hi! The scheme uses the exact resistor values ​​that are quite difficult to buy. Is replaced by the more popular. 750 Ohm-1500 Ohm-3kOm. I put these ratings, the scheme works well in SCART (sometimes yellow color much darker). AD725 chip I already bought but not yet put into the scheme ...

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uze6666
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Re: A Question about Resistor

Post by uze6666 » Tue Mar 19, 2013 12:59 am

The resistor used are 1% precision, they are standard but harder to find. So yes you can take the closest standard resistors and it will work. Attached is a schematic with standard resistors that I tested and works. Colors are slightly off and probably a bit too clear, but it's still excellent.
Attachments
Uzebox Game Console F3 (standard resistors).pdf
(28.42 KiB) Downloaded 169 times

john101
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Joined: Sat Mar 16, 2013 8:04 am

Re: A Question about Resistor

Post by john101 » Tue Mar 19, 2013 2:00 pm

I am john, this is my English name given by my English teacher when I was in college(My Chinese name is Yang Jun, she said it is hard to pronounce, so John is selected to replace Jun) .Now I am a lab teacher in a third-rate university :( in China,xi'an.
I know something about software,like C program, but always confused about electronics (analog electronic, especially some circuit using feedback). (I feel Digital circuit is much easier). One sensor experiment class I taught need some knowledge about electronics, so I have to review my knowledge about it. It is a little expensive to buy a UzeBox kits considering low exchange rate of Chinese money. Soldering one force me considering lots of things, I have found. UzeBox gives me a feeling like old friend, when I was young and did not have PC.

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DaveyPocket
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Re: A Question about Resistor

Post by DaveyPocket » Tue Mar 19, 2013 8:38 pm

What you could do is use a few variable resistors (potentiometer) and set them to a precise value with the help of a multi-meter. I recall someone doing that on the forum here...

Image

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uze6666
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Re: A Question about Resistor

Post by uze6666 » Tue Mar 19, 2013 9:52 pm

john101 wrote:I am john, this is my English name given by my English teacher when I was in college(My Chinese name is Yang Jun, she said it is hard to pronounce, so John is selected to replace Jun) .Now I am a lab teacher in a third-rate university :( in China,xi'an.
I know something about software,like C program, but always confused about electronics (analog electronic, especially some circuit using feedback). (I feel Digital circuit is much easier). One sensor experiment class I taught need some knowledge about electronics, so I have to review my knowledge about it. It is a little expensive to buy a UzeBox kits considering low exchange rate of Chinese money. Soldering one force me considering lots of things, I have found. UzeBox gives me a feeling like old friend, when I was young and did not have PC.
Hi Yang, I say your chinese names not hard at all to say! :) btw, there's also kits available and made in china that may be more affordable: http://imall.iteadstudio.com/im120829001.html.

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Kerby
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Re: A Question about Resistor

Post by Kerby » Thu Mar 21, 2013 10:10 am

The idea of ​​using more than one variable resistor - yes, you can set the exact value. What is the square in the left corner of the photo??

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Kilo
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Re: A Question about Resistor

Post by Kilo » Thu Mar 21, 2013 10:26 am

Kerby wrote:The idea of ​​using more than one variable resistor - yes, you can set the exact value. What is the square in the left corner of the photo??
I guess it's a RJ45 LAN-Connector for the selfmade Gamepads :)
The last digit of Pi is 7! I calculated this, as I counted to infinity yesterday!

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Kerby
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Re: A Question about Resistor

Post by Kerby » Thu Mar 21, 2013 4:04 pm

I also put the RJ45 LAN connector cable SCART. I did not like the SCART connector on the board, it's too big, almost as big as the board itself.

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