bipolar_12v_psu
Differences
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bipolar_12v_psu [2008/05/06 22:15] 127.0.0.1 external edit |
bipolar_12v_psu [2009/03/08 00:09] nebula |
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| 4 What cap size? | 4 What cap size? | ||
| - | 5 Wallmarts | + | 5 Wallwarts |
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| For many circuits, especially when using Opamps, we need a PSU that delivers +12 V, -12V and ground. | For many circuits, especially when using Opamps, we need a PSU that delivers +12 V, -12V and ground. | ||
| Here I want to demonstrate different methods of building such a supply. | Here I want to demonstrate different methods of building such a supply. | ||
| - | The first one uses a 15 V transformer with center tap, or two 15 V transformers in series. | + | The first one uses a 30 V transformer with center tap, or two 15 V transformers in series. |
| The voltage is rectified and applied to a standard stabilizing circuit using caps and 7812/7912 voltage regulators. | The voltage is rectified and applied to a standard stabilizing circuit using caps and 7812/7912 voltage regulators. | ||
| Why 15 V when we need 12 V? There is a voltage drop over the diodes in the rectifier. The mains supply may be 10% lower than the 230 V it´s rated for. The regulators need a voltage 3 V higher than their output to work correctly. | Why 15 V when we need 12 V? There is a voltage drop over the diodes in the rectifier. The mains supply may be 10% lower than the 230 V it´s rated for. The regulators need a voltage 3 V higher than their output to work correctly. | ||
bipolar_12v_psu.txt · Last modified: 2010/02/28 16:46 by nils
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