Optical obstacle switch - del50006
This is a simple toy that has many applications. Any
object that breaks a light beam will trigger a relay
to on condition for a period of time.
Description - The 555 monostable has a 1 second
period, If pin 2 gets low trigger pulses of a
frequency more than 1 Hz, the output pin 3 will
remain high, if the trigger pulses came in 10 second
delays then output will go on and off, so also the
relay and the electrical load on relay contacts.
Like an integrator, it will not operate relay very
fast. Even in a fridge stabilizer they put something
like this else the compressor motor is damaged on
frequent black-brown outs.
Retro-Reflective Proximity Switch
Now for the LM567 part, The clock at pin 5 flashes
the IR Transmitter LED LD1 at a frequency set by
C7-R5. The IR Photo Sensitive Diode or Transistor
LD2 conducts when light is got from the IR LED. As
the lights is in pulses, so also the impedance of
LD2 goes low and high at same frequency. This
develops an AC waveform across R3 over a DC
representing Ambient light. If direct sunlight falls
on this arrangement, the Photo-diode saturates, then
this circuit or any other circuit won't work.
But when ample protection from ambient light is
made, some pulses good enough for LM567 tone
detection, 100mV rms, is obtained and it operates
the relay via a LM555.
Image, Save to Disk, Print to Scale.
Build it Yourself.
The Artwork was made by a traditional PCB Artist
with Artwork tape, pads, Rotring Pen, and Knife.
This is scan of Hand-Made Artwork. Then we go to a
Offset printing, photo processing studio, he will
make a Positive and Negative of artwork with
photography. This is what you will need to make a
PCB. Positive Film and Solder Mask.
switch with photo sensors
The Artwork and Film are 1:1 or 1x, 300dpi scan. The
Solder Mask is shrunk to 1/2, it may not be usable,
i have to still build some graphics expertise and
using the scanner. The component layout is an
assembly instruction. I have no idea how you will
make PCBs out of this, try postscript printing or
ask a DTP professional. But if you manage to get a
scaled print, and you know screen printing or even
have a photo resist fluid. you can make prototypes
at home. I used to do it in my younger days.