File:UPC1237 speaker protection 2. Decrease relay current with RC.png
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English: Use of uPC1237 speaker protection IC. 2. Improving current draw by adding RC ballast into relay drive path. With parts shown, relay current decreases from 20..30 mA (depending on rail voltage) to 6...9 mA. The diode D2 speeds up discharge of C5 at power-off. Update: The turn-on delay network R5C4 (same as in datasheet) considerably slows down the turn-on transient of the uPC1237's output transistor. This requires a fairly hefty C5 of at least 470uF. With 220uF the circuit may not work correctly, to the point where the relays won't turn on at all. The only way to ensure relay turn-on is to increase C5 to 470 uF; this certainly works with 100 uF timing cap. Likewise, if you feel like increasing turn-off delay, increase C5 accordingly. |
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| Source | Own work |
| Author | Retired electrician |
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I, the copyright holder of this work, hereby publish it under the following license:
 
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This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 05:41, 12 January 2023 | | 1,553 × 801 (169 KB) | Retired electrician (talk | contribs) | upd |
| 00:42, 10 December 2022 |  | 1,534 × 809 (150 KB) | Retired electrician (talk | contribs) | {{Information {{Information |Description={{en|Use of uPC1237 speaker protection IC. 2. Improving current draw by adding RC into relay drive path. The diode D2 speeds up discharge of C5 at power-off. }} |Source={{own}} |Date=2022-12-10 |Author= Retired electrician |Permission= |other_versions= }} Category:UPC1237 |
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