DARKROOM TIMER 240v Switching

This section does the 'work' and at rest, it permits a
240vAC 3amp Solid State Relay allowing a 'SAFELIGHT'
(10w to 20w with appropriate filter) to be switched 'ON'
in this, the 'standby mode' which can be used for
preparing the next job to be exposed.

Now, when the PIC is in the 'GO' mode, the output from
the PIC > Transistor > 5v Relay which then operates
and switches the other 240vAC Relay which permits
an Exposure light load of up to 720watts, (normally
only 15w for ORTHO Film or a 'raft' of 30 x 20w fluro
UV 350 angstrom Tubes, for RISTON Negative Exposure
or it can operate a 240vAC contactor which can switch
a 'shutter' that can permit the light from a 400w or 3600w
mercury vapour lamp for faster Negative Riston Exposures
A 5v low voltage 'FOCUS' switch can be easilly connected,
across the bottom of the Diode and Negative, in case you
you using an enlarger (Durst or Meopta etc) or it can
provide MANUAL Operation, (PADS are there on the
circuit board), planned ready for extra time if/when ever.
In 'MANUAL' mode it still follows correct operating operations
protocol, that is, if EXPOSURE is 'ON' then SAFE-LITE is OFF
The small 5vDC relay only switches minute current to
the Solid State relay, and thus as it is working under no
real load conditions, it should last a few million operations.

This project Does NOT NEED 240vAC connected to work
just a 5/6vDC or 12vDC plugpack from JAYCAR / Altronics etc
as a standard (Countdown TIMER), the Solid State relays are
there if you want them to 'auto switch' the external items
usually a 240vAC enlarger (up to 720w) and a Safelite, again
usually a couple of 20w fluro tubes wrapped in 'RUBY-LITH'
or a real Safelite housing with an 'OA' or '#3' filters
'OA' or RED/YELLOW light bulbs (NO UV) for RISTON or Photo Paper
and (7w lamp ) KODAK #3 if you are using Photo-type setting
Black & White film or normal Panchromatic 32asa film etc

Section B
240v Safelight & Exposure

Exposure & Safe Light Control

Don't forget to send in an S.A.E. for an
A4 checkplot of the circuit board etc.