the lamp driver transistors q7 q13 etc turning on lamps i1 and i2 transistor q2 39 s collector goes negative and pulls pin 4 of integrated circuit ic3 to ground and pin 2 to ground resetting and triggering integrated circuit ic3 as long as transistor q2 39 s collector and pin 4 remain at ground potential integrated circuit ic3 is off and not timing as soon as the timing cycle of integrated circuit ic2 has ended pin 3 goes positive transistor q4 39 s collector is negative through diodes d3 and d4 lamp i1 goes off and lamp i3 comes on lamp i2 remains on via diode d4 39 s anode being connected to diode d2 39 s anode the on off timing cycles carry on until switched off the timing cycles are determined by resistors r7 r8 capacitors c5 for integrated circuit ic2 resistors r12 r13 and capacitor c7 for integrated circuit ic3 resistors r17 r18 and capacitor c9 for integrated circuit ic4 etc the circuits are made variable by the resistor r7 from 0 to approximately 60 seconds for integrated ic2 and ic4 and from 0 to approximately 5 seconds for integrated circuits ic3 and ic5 switches s3 s4 s5 and s6 lock the timers in a particular mode by holding the transistor 39 s collectors transistors q2 q3 q4 q5 to ground switches s4 and s6 not only lock the timers in that mode but also ground integrated circuit ic1 turning it on set to oscillate instead of holding 34 time 34 pin 3 remains on for half of its timing cycle for the other.