"Does it take special wiring to start the motor once again, after it has been shut off by the first reed swt ?"
Originally Posted by HDGTX
Thanks for the info, simple is always a good plan. I have
a couple of questions;
Does it take special wiring to start the motor once again, after it has been shut off by the first reed swt ?
Will each reed switch position require a seperate relay to break the current flow for each new AR stop ?
Would someone sketch this out and display it for us ?
Do you think proxmity switches would work in the same way as a reed swt ?
Rharkenss, do let us know what they tell you. They sent me a pdf of the instruction maual. I can email that, if somone wants it, just PM me.
No special wiring is required. This entire control system can be built without the aid of any solid state circuitry."Will each reed switch position require a seperate relay to break the current flow for each new AR stop ?"
NO and YES. It depends on the current draw of the motor. If the motor draws more current than the reed switch contacts are capable of handling, then the reed switch contacts will burn out. In that case, a second relay will be necessary for current handling capability. In the worst case, two relays will be required to control one masking motor. Three position masking systems (Retracted, 4:3 and 16:9) will require three reed limit switches and may require three relays, again depending on the motor's current draw.Do you think proxmity switches would work in the same way as a reed swt ?
There are several thypes of proximity switches. Ex: photoelectric, inductive, ultrasonic, binary, etc. The magnetic reed switch is a proximity switch in a simple form.
Here's an overview of my proposed control system:
A relay is a simple electro-mechanical switch. Applying voltage to the relay coil moves the relay contacts. The relay contacts act as a switch passing voltage from an external power supply to the masking motor, turning the motor on or off and reversing the motor's direction.
This system can be IR controlled with a Xantech IR activated relay or can simply be connected to the projector trigger. Using the PJ's trigger is simplicity in itself.
The projector trigger can be used to activate the coil of a Double Pole Double Throw relay (DPDT). In many cases, the PJ trigger may not have enough current to activate a relay coil. In this case, a solid state circuit can be used to activate the relay coil. Even easier, a special relay called a sensitive relay is designed for this purpose.Caution: DO NOT attempt to use the PJ's trigger output to power the motor.
A. When the PJ's trigger is active, the relay can apply power to the masking motor.
B. When the masking has extended to a preset point where the magnetic reed limit switch is activated, the limit switch opens the circuit stopping the motor.
C. When the PJ's trigger is then deactivated, the contacts of the DPDT relay in it's off state can provide power to overide the limit switch, re-starting the motor and in turn moving the masking system back to it's retracted position. A second limit switch will prevent the masking from retracting too far.
D. Basically, two limit switches are required per masking panel. One limit switch sets the fully extended position and the second limit switch sets the fully retracted position. Three position masking systems (2.35 AR when retracted, 4:3 and 16:9) will require three reed limit switches (a limit switch for each position) and may require three relays, again depending on the motor's current draw.
E. Utilizing a DC motor in automating this DIY masking system will simplify things greatly. With a DC motor, the same DPDT relay which is activated by the PJ's trigger, if wired correctly, can reverse voltage polarity to the masking motor. This will reverse the motor's direction, returning the masking system to it's fully retracted position.
This concept is actually very simple to assemble, wire and implement. It should also be very reliable.
I'm happy to assist the first guinea pig who wishes to implement this proposed control system.
EDIT: The number of programmable trigger outputs your PJ or Video Scalar offers will determine whether or not you can control a three position masking system (2.35 AR when retracted, 4:3 and 16:9). You'll need two trigger outputs for three positions. If you only want a two position masking system (16:9 / 4:3) then one trigger will suffice. If you don't have enough trigger outputs, then the Xantech IR Relay block will provide complete control.