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av:lm1881

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av:lm1881 [2009/09/02 08:58] 189.136.179.33av:lm1881 [2016/05/12 16:00] – [Usage Notes] Snatcher
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   * You can safely ignore pins 3, 5 and 7.   * You can safely ignore pins 3, 5 and 7.
   * All the parts are small enough to fit in a DB9 connector.   * All the parts are small enough to fit in a DB9 connector.
-  * The LM1881 circuit is useful to generate a composite sync signal from a composite video signal. Connecting a c-sync signal to the input of an LM1881 causes problems and should be avoided.+  * The LM1881 circuit is useful to generate a composite sync signal from a composite video signal. Connecting a c-sync signal to the input of an LM1881 may cause problems and should be avoided
 +  * It should include a 75 ohm (or thereabouts, the value isn't critical) resistor between the input and ground, before the coupling capacitor. This sets the optimum video level and combined with the lower line impedance and reduced noise, give the LM1881 a much better chance of seperating the sync from a video signal which is changing from bright to dark rapidly.
av/lm1881.txt · Last modified: 2019/08/27 20:45 by 127.0.0.1