Home  Articles Advanced Gearbox Tech II: Solid State Switching with MOSFETs
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Advanced Gearbox Tech II: Solid State Switching with MOSFETs |
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Written by Jay
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Tuesday, 10 May 2005 |
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Page 8 of 10 Installation Instructions
Step 1: Disassemble Mechbox and Remove Switching Assembly
The switching assembly is held in place by only 1 screw. Once the screw is removed, the entire assembly can be removed easily.
Step 2: Desolder/Resolder Trigger Contact Wire
Once the switch assembly has been removed, desolder the "trigger wire" and resolder it to the "selector wire". It is advised that a heatsink clamp is used or to remove the metal contacts from the plastic assembly prior to soldering so as to avoid melting of the switching assembly.
Step 3: Add Gate Wire
Measure a long lenth of thin 24 gauge wire and solder one end to the trigger contact where the trigger wire was removed from in Step 2. This wire will serve as your gate wire, and should be routed through the mechbox following the wiring channels and out the back.
Step 4: Mount MOSFET and Gate Resistor Mount the MOSFET on the small PC board by poking the 3 pins through the holes on the surface of the board. Select a position on the board adjacent to the gate pin, and mount and solder one end of the 100 ohm gate resistor to the pin.
Step 5: Mount Discharge Resistor
Select a position close to gate pin at one end and the source pin at the other, and mount and solder the 30k discharge/pull-down resistor, with one end to gate and the other to source. Be sure to leave enough space near the source pin soldering another wire in the next step.
Step 6: Solder Wiring
Solder the gate wire to the unsoldered end of the 100 ohm gate resistor to complete the gate connection. Cut the negative battery to mechbox wire (black wire) and solder the mechbox end to the drain pin. Solder the battery connector end of the black wire to the source pin. If the wiring is not long enough, extend the wires using 20 gauge braided wire.
Completed Installation:
Step 7: Testing Procedure
Set a multimeter to measure DC voltage, and connect the probes to the 2 motor contacts on, positive to red and negative to black. Next, connect your battery to the battery connector. The multimeter should show a miniscule voltage, or zero. Put the selector plate to the semi or full-auto position, and squeeze the trigger. When the trigger is squeezed, the multimeter should show the full voltage of your battery. Next, let go of the trigger. The reading should now instantly fall back down close to zero.
If your circuit passes the above test, the installation is successful and you are ready for a live fire test. It is recommended that the entire circuit board is wraped with electrical tape or sealed with RTV to protect against environmental factors.
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