Description of Circuit Flow
When the Circuit is plugged in:
• A "Wall-wart" (JameCo, #163651) converts U.S. standard +120 Volts AC to +24 Volts DC.
• Positive current from the Wall-wart enters the circuit, which is primarily in parallel formation.
• The Wall-wart's positive current is spliced to the Source terminals of 30 N-Channel Enhancement MOSFETs, where it waits for a gate to be thrown.
(Lefthand wire of each MOSFET is Source.)
• At this point the AC-to-DC current just sits there doing nothing to the coils until the micro is given instructions.
• Needless to say, the MOSFETs will be thoroughly heat sinked and insulated from each other to prevent shorting through the sink itself.
(Top Left wire of each MOSFET is the connection to Ground, usually where the unit screws down to the heatsink. The Ground that these feed into is supposed to illustrate this, however, it may be wiser to attach a Vcc here, whatever that is. ? )
How the Circuit is armed:
• A Hat Switch is used to "power on" the OOPic micro, which is juiced by either a 9 Volt or 12 Volt DC Battery.
• Once the OOPic is alive, a PWM Fan Driver kicks in on one of the I/O Lines and proceeds to cool the MOSFETs. After the PWM Fan Driver is in operation, it stays on for as long as the OOPic is on.
Ideally, this would be independent of the OOPic and would be brought to life by the Wall-wart current for greatest operational safety.
• A Hexadecimal Keypad (B.G. Micro, #SWT1067, 4 x 4 matrix) is attached on I/O Lines 8 thru 15 on the OOPic2+ module.
• When a key is pressed on SWT1067, the OOPic2+ receives it and proceeds to initiate and run a programmed pattern that is assigned to that keypress value.
• The pattern is used to send output charges to I/O Lines, which tie into Demux ICs (such as the 74155, not shown) that are used to send cascaded output charges in the pattern needed to fulfill the example timing chart above without requiring 30 I/O Lines to do it.
How the Coils are fired:
• First of all, a clarification. The I/O Lines will no longer be spliced by switches, they will be activated very rapidly in the code of the pattern itself to achieve near-simultaneous action.
• When an I/O Line is charged, its +5 Volts of DC current travels from the Demux ICs and through a 220 ohm Resistor, then it's applied to the Gate terminal of a MOSFET.
(Middle wire of each MOSFET is the Gate.)
• Before reaching the 220 ohm Resistor in-line with the MOSFET, the I/O Line's +5 Volt DC current is forked off through a 20mA Red T-1 3/4 LED, then travels through another 220 ohm Resistor before connecting to the Ground on the 40-Pin Header of the OOPic's PCB.
(Don't ask me, I think the order in which the +5 Volt DC current comes in contact with these components is wrong, but that's what I was told by somebody. Also, the wire crossing all the I/Os represents the 40-Pin Ground.)
• Once the MOSFET's Gate is charged, the switch is closed and the Wall-wart's +24 Volt DC current is allowed to go to the MOSFET's Drain terminal.
(Righthand wire on each MOSFET is the Drain.)
• From the Drain of the MOSFET, the Wall-wart's +24 Volt DC current is sent to a Wire terminal (either screw-type or something similar), which is accessed and connected to on the outside of the circuit's Enclosure.
• Upon reaching the terminal, the Wall-wart's positive voltage is sent to the Solenoid coil via a 16 to 18 AWG wire (speaker wire) with a length of 29 feet.
(This length is necessary to accomodate the following measurements in feet:
Square root of [(10^2) + (16^2)] or approximately 19, plus 10. This gives the hypotenuse of a maximum safe distance of 10 feet from the cameras and a 16 foot horizontal width of the track for the cameras, added to a ten foot maximum allowable vertical height for the camera mount. This will allow for the bulk of the circuit to be placed in the middle or at either end of the camera mount with no risk of pulling loose any wires leading to the coils.)
• After passing through the Solenoid coil, the Wall-wart's +24 Volt DC current is sent to Ground via the negative wire of the Wall-Wart.
• To protect the MOSFETs and the rest of the circuit from the Reverse Peak Voltage of the Solenoids when they're switched off, Coil Supressors are placed across the coils' positive and ground wires. These consist of a Reverse-Biased Diode and a 100 Volt rated Resistor.
Denouement:
• The path of the flow is complete once the +24 Volt DC current from the Wall-wart has been sent to Ground via the Negative wire of the Wall-wart.
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