The first magnetic switch has been installed.
I initialy though I would need a complicated electronic circuit but not at all...
The UCC is perfectly able to deal with that alone. read on.
Over the last few month, the UCC has been greatly updated - one of those modifications was to adapt the PCB lightboards to drive not only 5v leds but real aircraft 28v bulbs (or any voltage between 5v and 28v).
The first mag switch will be the JFS start. Although the real one is a 3 positions, I will use a two positions one. Indeed start1 is not implemented, so start 2 will do.
The 5v is not enough to keep the magnetic switch into the start2 position, I used 24v for that purpose.
When the switch is placed in start2, the JFS run and the JFS run light comes on. That shared memory bit will command the JFS switch.
I thus set two output on the UCC for the JFS run light. The first one for the 5v green led which is on the jet start panel. The other output will use the 24v and drive the switch coil. That voltage is given by an external power supply. 28v Vcc is connected to the + of the magswitch coil, the 28v ground is connected to the relevant ground input of the UCC lightboard.
only the minus of the regular led output on the UCC lightboard is then connected to the - of the magswitch coil.
A protection led is connected through + and - of the coil - that's where I had most of my newbees problems :oops:
- I activate the switch into the Start2 position - at this time the switch doesn't stay in position
- The switch sends the JFS keystroke to F4 and fires up the JFS indicated by the JFS run light on the Jet start panel that comes ON and the coils gets energized and the swicth stays in position
(this happen very quickly
Once the engine has started and RPM are rising to a certain level, the JFS Run light comes OFF and at the same time the coil is de energized, releasing the JFS switch to the OFF position
with a noisy SNAP!
Here's a video of the action
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A big big thanks go to Loulou and Sharknoir to have helped making this first test a success - you guys are terrific
Next step is activating the Parking brakes and AP magnetic switch.