Theo Verelst Mixed Analog Digital Electronics Ideas page

Sort of a mixed bag of ideas partially already implemented and tested, most of the circuit diagrams are from the top of my head, but almost doublessly would work after minor or no additional engineering.

Low voltage multichannel pwm power control

Using the PWM depth control loads up to 50Amps or so can be power controlled. Lamps and heaters should be fine, motors ans other inductive loads may need different oscillator frequencies than this ca. 1kHz, which can be easily arranged. I forgot the part number of the powerfmosfets I used, I seem to remember they switched fine into the megoherz range, and when directly steered from logic (with good charge coupling properties) hardly suffer from their large gate capacitance, and dissipate energy roughly based on their Ron, which as as I remember it was something like 0.005 Ohm, for a $2 "tip" type device. I used it to dim car headlights without the need for a heat sink. Comparators can be of simiple type. 



           |------|
        |--| 10k  |---------
        |  |------|  +5V   |                  |------|
   -----|           |\|    |          12V o---| 7805 |--------o +5V
   |    |-----------|-\    |                  |------|  |
   |    | 10nF      |  >----                     |     ---  100nF
   |   ---       |--|+/    |                    ---    ---   //
   |   ---       |  |/|   ---                           |   100uF
   |    |        |   ---  | | 10k                      ---
   |   ---       | comp   | |
   |             |        ---
   |             |         |
   |          --------------
   |          |     |
   |         ---   ---
   |     10k | |   | | 10k
   |         | |   | |
   |         ---   ---
   |          |     |
   |   +5V o--|    ---                        +12V
   |          |                                |------
   |         ---                               o     |
   |     8k2 | |                              Load  ---
   |         | |                               o    / \
   |         ---                               |     |
   |----------|------| |\                      |------
             ---     --|-\      A      B    |---
         10k | |  C  D |  >-----o------o----|     Power Mosfet
             | |<-o--o-|+/                  |->-  (will look up #)
  PWM depth  | |       |/                      |
             ---      comp                     |
              |                               ---
             ---
         8k2 | |
             | |
             ---
              |
             ---

Improvements and additions to the above

To give theabove design touch or other control, CD should be broken, and D can be used as a voltage control input, roughly linear between 5/3 and 10/3 Volt. For touch control, add the folowing units, and use a fet input comparator (of buffer in between): 

                                         -------------------> D
    o---+5V            |\                |              |
 "touch"               | \            |---              |
    o------------------|  >---------->|    1/4 4066    --- 1uF
           |      |    | /            |---             --- MkM
    1MOhm --- 1nF |    |/                |              |
          | |    ---   CMOS            E o             ---
          | |    ---   Buffer            |
          ---     |    (e.g. 1/4         |
           |      |    74HC00)         F o   |------|
          ---    ---                     |---|      |---o Udes
                                             |------|     (e.g. 0V,
                                                          2.5, or 5V)

EF can be broken to force a voltag eon E. Otherwise, a slow intensite change results to Udesired.

Microprocessor control

Power driving is quite easily controlled by microprocesors. The display and (fast) cmos Z80 card decribed in the synth sections can act as car microprocessor basis system quite well and quite cheap, except I don't know wether the military spec-ed parts should be used for very high and low temperatures. The 16 7 segment LED display can hold simple, well readable texts (even from distance), and the whole system can be low poer enough to even remain active for weeks on an average car battery, with out the need for recharge.
It is also quite cheap to add alarm channels (either through very slow (cheap) AD circuitry or simple inports, and to add activation channels such as the powermos based driver above, which an quite easily be steered from an interupt based PWM software routine, and even have software based elaborate timer capacities added without to much difficulty.

To drive units with zero mass connection (usual in cars), a p channel fet could be used (if availalble), or this circuit extension: 

                                         |\|        |-------|
                                     |---| |--------| 78L05 |--
                                     |   |/|    |   |-------| |
                                     |         ---      |     |
                                     |         ---      |     |
                                     |          |       |     |
+12V o-------------------------------|------------------------|-----
                       |             |   |                    |    |
           |------|    |             |  ---            --------    |
       ----|      |----|---|         |  \ /            |           |
       |   |------|  |\|   |         |  ---          |\|           |
       |             | \   |   | |   |   |           | \        |---
       |-------------|  >O-|---| |---|----       >---|  >-------|
      ---            | /       | |           PWM in  | /        |->-
      ---            |/|                             |/|           |
       |        Schmitt tr.                           ---          |
       |               |                            Buffer         o
       |               |                            (TTL in ?)   Rload
       |               |                                           o
       |               |                                           |
  0V o--------------------------------------------------------------

Some more high level car based ideas

Remote controlled cameras (ccd units) with servo control (over existing RC model channels and equipment), UHF modulator (cheap FCD allowed (?) 50mW), preferably directed antenna. Add notebook for more possibilities.

Laser based communication channels

Modulation rate for power LED'S? (tried a few 10's of kHz at least) parabolic slightly diffusely mirroring capture dishes. 10cm diameter or so to deminish possible danger to the eye and susceptibility to rain, snow and birds.

Combination

Remote controlled dishes (moulded plastic, alu foil deposit based?). Source search algorithm, also on complementary phototransistor dish. Defocus ("large angle" scan) option, mechanically or second (displaced photo transistor).

Possible bandwidth for decreased modulation index, geometrically locked channels (between stationary objects, possibly behind windows? Might be sufficent to have a cheap, supplier independent high speed computer link. How about a block IP equivalent, and mulitple controlled dish units? Just hope the neighnours leave their equipment on when they leave, or at least some of them. What would be the range? The price shouln't be the problem, servos are relatively cheap, optical dishes are mass producable, laser diodes exist,...