2x1N4148          ___                      4xBCW66
                                       ---|___|---
                ___    ||        |\|  |    ___    |
MAX232/pin4 o--|___|---||----*---| |--*---|___|---*----------*---------------*----o VPP
(C+ 0..8V)      220R   ||    |   |/|  |    2x1k   |          |               |
  ~40kHz              100nF  |        |           -          |               |
                             |      -----        | | 68k     |               |
                      |\|    |      -----        | |         |               |
MAX232/pin2 o---------| |----*        |  1u       -          |               |
(V++  8V)             |/|             |           |          |               |
                                     ---      ----*          |               |
                                             |    |          |               |
                                             |    _          |               |
                                 fit jumper  o   | | 39k     |               |
                                  for 8V     o   | |         |   TL431       |
                                open for 12V |    -        ,---'             |
                                             |    |          ^               |
                                              ----*---------/ \           ---*
                                                  |         ---          |   |
                                                  -          |           |   |
                                                 | | 27k     |           -   |
                                                 | |        ---         | |  |  22k
                                                  -                     | |  |
                   +5V                            |                      -   |
                    o                            ---                     |   |
                    |                                                    |   |
                    -                                                    | |/
                   | |47k         -----------------------*---------------*-|
                   | |           |                       |                 |\>
                    -   47k      |                       |                    |   +5V
                    |   ___    |/                        |                    |    o
ATMega8/pin13  o----*--|___|-*-|                         |                    |    |
(/VPP)              |        | |\>                       |                    |    -
must go up          |  |/|   |    |                      |                    |   | |
6-7us after RST      --| |---     |               -------                     |   | |
                       |\|       ---             |                            |    -
                        1N4148           47k     |                            |    |      MCLR/VPP
                   +5V                   ___   |/                             *----*----> DIP8/pin4
                    o            -------|___|--|                              |
                    |           |              |\>                            |
                    -           |                 |                           |
                   | | 47k      |                 |                           |
                   | |          |                ---                          |
                    -           |                                     47k     |
                    |           |                                     ___   |/
ATMega8/pin32  o----*-----------*------------------------------------|___|--|
(RST)                                                                       |\>
                                                                               |
                                                                               |
                                                                              ---