INSTRUCTIONS FOR THE DUAL TIMER
Reminder – to prevent accidental damage please make sure the power is not connected when you are making or altering any of the wiring connections
The Dual Timer has been redesigned to increase its functions by adding a random option.
The Dual Timers purpose is to switch on or off an electrical device such as a bulb,electric motor, track isolation section, servo motor controller, electronic circuit board, etc, for an adjustable amount of time. The Dual Timer has two timers which can be used separately or linked together (to give sequencing).The second timer can be used to give random timings instead of fixed timings if required. Each timer circuit switches relay contacts whilst timing. These relay contacts are in effect the equivalent of an electrical SPDT switch.
The time is adjusted with pots. The timing interval can be adjusted between9and 132 seconds. An indication of the length of timing is given by the LED fitted to the board. Whilst timing it flashes; the longer the flashes the longer the timing interval. Pot1 and Pot2 are rotated to adjust the timing interval of their timers.
To start timing the “in1” or “in2”terminal is connected to 0V.This may be done by using a switch or the “out” terminal of another timer (the other timer on the board or a separate Dual Timer) or the output of one of our other boards for example terminal 2 on the irdot-1 or terminal “P”on the IRDOT-P or terminal F on the Dual Servo Motor Controller. At the end of the timing interval “out1” or “out2” give a short 0V pulse.So by connecting “out” to “in” the timers will operate in a sequence.
Power supply
Power connects to terminals “0V” and “+”. Ideally a 12 volt DC power supply should be used although the board will work from a supply of 12 to 16 volts either AC or DC.
Operation of the Terminals
“start” If you wish one or both of the timers to start timing each time you switchthe power onto the board connect the “start” terminal to the relevant “in” terminal. The diagram shows “start” connected to “in1”, also connected to “in1” is a push button (push to make) switch which connects 0Vto “in1” to start timing.When power is connected to the board start gives a 0V pulse which lasts for 5 seconds.
“out1”When timer 1has finished timing this terminal gives a short 0V pulse. Its purpose is to activate a second timer when the first has stopped timing. Out1 could also be used to latch a latching relay board.
“in1” When this terminal is connected to 0V, timer 1 begins timing. The length of timing is the same regardless of whether the 0V is removed during timing or still present after timing has ended. However for timing to start for a second time the first 0V pulse must have ended and a second 0V must be applied to “in1”. For example suppose terminal 2 of an IRDOT-1 is connected to “in2”and the timer is connected to an electric motor and adjusted to switch the motor on for 30 seconds. If a train stops over the motor for 15 seconds then leaves the motor will switch on for 30 seconds. If a train stops over the motor and remains there for 5 minutes the motor will still only switch on for 30 seconds and the motor will not restart until that train has left and a new one arrives.
“in1”and “in2”may be activated by terminal 2 of an IRDOT-1, terminal P of an IRDOT-P (provided these boards are powered by the same power supply as the Dual Timer). By relay contacts or a switch or a push button switch provided they are wired to connect 0V, by the start out1 or out2 terminal of a timer etc.
Relay ContactsA relay is in effect a switch operated by electricity rather than being manually changed.
“com” common relay contact
“B”relay contact connects to common when timing
“A” relay contact connects to common when not timing
Figure3 above shows the position of the relay contacts with timer 1timing and timer 2 not timing. The relay contacts act as a SPDT (changeover switch) when timing they connect com to B. When not timing they connect com to A.
Note the relay contacts have no electrical connection to the rest of the relay board. This allows them to be used to switch different electrical circuits, for example track isolation sections. Treat them as SPDT (changeover) switches.
Adjusting the time. The timing length is adjusted by rotating the variable resistor with a small screwdriver. Turn clockwise for shorter times.
LEDTwo LEDS are fitted to the board, one for each timer. These flash whilst the board is timing. The slower the flashes the longer the timer is adjusted for.
“RAND” This terminal is for random operation. For example it can activate a dual servo motor controller this could be used to make a crane, forklift truck etc move at random. Whilst the RAND terminal is connected to 0V (shown by thicker line) the relay is switched off and on in a “random sequence” After every random timing the relay switches from on to off or off to on. At the end of each random interval “out2” will switch to 0V to give a short pulse. If it is required to activate a relay for a fixed time at random intervals out2 may be connected to in1. This will cause the relay contacts of timer 1 to give a fixed length pulse at the end of every random interval.This is shown in figure 4.
If connecting to a servo motor controller a wire from 0V should be connected to com and “B” should be connected to “S” on the servo motor controller. Both circuit boards should be powered from the same power supply.
“in2” Starts timer 2 when 0V applied. Functions identically to “in1”.
“out2” Functions identically to “out1”
“com” Timer 2 relay common contact
“B”Timer2 relay contact, connects to com when timer is timing.
“A” Timer2 relay contact, connects to com when not timing.
Chaining timers togetherto make a sequencer
By connecting“out1” to “in2” and “out2” to “in1”the relays will time alternatively indefinitely. This can be extended to include other Dual timers in the sequence. However one of the timers needs to receive an initial pulse to start this sequence. The initial pulse could be provided by either the “start” terminal, a push button switch an IRDOT-1 etc. This connects either “in1” or “in2” to 0V. If you wish to stop the sequence then the connection between in and out must be broken by either a switch or relay contact.
Use with IRDOT-Ps for storage sidings
Com A (dual timer relay contacts) FIG6
Storage loops can be automated by fitting an IRDOT-P at the end of each siding where the train is to stop. When the IRDOT-P detects the train arriving it will switch the points for the next line so isolating the arriving train and activating the departing one.Self isolating points are used so that when the IRDOT-P switches the point the point isolates the arriving train and energises the departing one.
Train enters siding 1 reaches IRDOT-P at A which switches points a b c and d to siding 2. Train departs siding 2.
Train enters siding 2 reaches IRDOT-P at B which switches points b and c for siding 3. Train departs siding 3.
Train enters siding 3 reaches IRDOT-P at C which switches points a and d for siding 1. Train departs siding 1.
We are now back at the start of the sequence which repeats. This can be extended to any number of sidings.
The Dual Timer is used to give a delay between a train arriving and the next train departing (timer1 does this) and also to prevent the departing train activating the IRDOT-P it is crossing and so preventing the possibility of the points changing with a train half way across them (timer2 does this).
On detecting the train the IRDOT-Ps “P” terminal switches to 0 volts for approx 1 second. All the "P" terminals are wired together into "in1" of timer1; so when a train arrives at any IRDOT-P the IRDOT-P will start timer1 timing. Whilst timing, timer1 opens its relay (ie “com” and “A” are disconnected by the built in relay whilst timer1 is timing) for the timing interval so isolating all the sidings. See FIG7 and FIG8.
As timer1 finishes timing its “out1”connection will momentarily switch to 0V. As “out1” is connected to “in2” this will start timer2 timing. Whilst timer 2 is timing its built in relay connects “B” and “com”. As “com” is connected to the “0V” terminal and “B” to each “I” terminal of the IRDOT-Ps (shown by the thicker line on the diagram)0V will be connected to the “I” terminals. This prevents the IRDOT-Ps operating the points until the timer has finished timing, thus preventing the points moving as a train crosses them.
Rail breaks shown on the centre 2 rails of the loops are only necessary for electrofrog points and are not needed for insulfrog.
Heathcote Electronics, 1 Haydock Close, Cheadle, Staffordshire ST10 1UE
Tel/Fax 01538 756800
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