A question about alternative power supply for hp41 series

[wojtek]

(02-18-2016 05:15 PM)Artur - Brasil Wrote:  Another solution, with simple parts:

Code:


 +--------+------------------------------------+-----------------------------+
 |        |                                    |                             |
 |        \                                    /||                           |
 |        / 1k                                 /||  470uH                  -----
 | +      \                                    /||                 2x 1.5V  ---
---       |                              470pF |       /        (parallel?)----- 
---       +---------+-------\            -||---+------>|-----+----o +       ---
 |1000uF  |         |         \         /      |       /     |               |
 |        |         \  2.2K     \     /        |      zener  |+              |
 |        |         /               /          |            --- 100uF        |
 |        |         \             / \          |            ---              |
 |      c |         |           /     \        | c           |               |
 |         \|_------+---/\/\/-/        \----_|/              |               |
 |      e </|                  1k            |\> e           +----o  -       |
 |        | bc547                              | bc547       |               | 
 |        |                                    |             |               |
 +--------+------------------------------------+-------------+---------------+

What should be the breakdown voltage of the zener diode here?