A simple, cheap bipolar power supply

[Synthaholic AKA sPEW]

Here is a simple bipolar linear supply.  Using good heat sinking, over
1 ampere is available from each pole.  Other regulator ICs are
available at higher currents using this same basic circuit.  Increase
the size of input filter caps for higher currents.  Also increase
current capacity of the xfmr for higher currents.  General rule of
thumb is that if it isn't too hot to keep your finger on, it isn't
overtaxed.  Make sure your filter caps can handle at least 10% more
than the PEAK xfmr voltage.  I use 50 volt caps for this voltage
range.

Here is an ascii-matic:


                                                      LM340T 15
                                                     +--------+
               1N4001                                | pos 3  |    +15
             +--->|------------------------------+---| term   |--+--->
             |                                   |   | reg    |  |
             |                                 + |   +---+----+  |
 ------    --+             LM320T -15           ---      |      +|
       )||(  |            +-------+         500 ---      |      ---
 wall  )||(  | 1N4001     | neg 3 |              |       |      --- 1
 wart  )||(  +---|<--+----| term  |----+---> -15 |       |       |
 120v  )||(          |    | reg   |    |         |       |       |
       )||( 12V      |    +---+---+    |         |       |       |
       )||(         ---       |       --- 1      |       |       |
       )||(    500  ---       |       ---        |       |       |
       )||(         +|        |       +|         |       |       |
 ------    ----------+--------+--------+---------+-------+-------+
                                                                 |
                                                                 |
                                                                gnd

- Scott Gravenhorst (Synthaholic)     www.concentric.net/~chordman

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