POWER
SUPPLYS AND RELAY BOX.
Overview.
There
are two power supplies in the sim… one is a regulated 13 volt commercial supply
(CB type of thing) which does all the 12 volt stuff except the DC supply for the
wiper motors…. The power supplys are mounted at each front corner of the sim…
at floor level. The idea here is to
get as much weight as possible up the front to counter the weight of the
pilot…. Also up the front is the main computer and underneath the front is the
control computer.
The
wiper motor power supply consists of a real basic configuration… a hefty
transformer, a hefty bridge rectifier (25 amp) and some large capacitors.
I
had to allow for both motors starting, under load, at the same time so I
allowed for 8 amps at 18 volts D.C. but in reality I ended up using about 15
VAC in which gives about 22 VDC out (Multiply the AC input voltage by 1.414) so
it was still under the maximum of 24 volts for the variable speed unit.
Note
for the purists: Yes the voltage will
droop under load.
Relay box…
The
relay box is in-between the output module from the control computer and before
the softstart / variable unit for each motor.
It is the really the heart of the control of the motors as to which motor
is going to go, which direction it will go in and cuts the power to a motor if
it has reached the limit of its movement. (Sensed by a micro switch on the
gearbox cam)
A
critical relay in here is what I call the “action” (or centering lockout)
relay… This relay is controlled only by the control computer and over-rides the
automatic self centering of the units.
So
if the computer says to go nose down (or up) it will happen, no matter where
the self centering is, it will happen.
The
construction of the relay box is something I am not proud of…. It was always one of those things you throw
together to make sure it works, with the intension of going back and building
it properly. The picture shows this…..
sorry. L
An
old box with a back plate and on it I hot glued the relays. The relays on the left handle one motor and
the other motor is handled by the relays on the right.
NOTE:
The 22 VDC (or 18 or whatever) only goes to the motors via the relay contacts
then to the varispeed units and it is NOT earthed.
NOTE:
The relay coils are activated by the regulated 12 DC supply.
The
above diagram was kindly drawn and donated by Erich, a great guy and fellow sim
builder. In fact he made me think on what I had drawn, (old hand drawn
diagrams) and has changed my ways.
That’s one thing I like about the flightsim community, we are all in
this together and we help one-an-other.
Well
done Erich and thanks heaps. People like you are one in a million. ! !
The
above circuit is for one motor only…. It is duplicated for the other one…..
Hence the reference to 2 different colors of wire. I.e. wire 5 on one unit
is purple for the pitch and on the other unit it is grey for the roll.
The
above picture is available as a separate download here…. http://www.jimspage.co.nz/relay.zip so you can print it out.
CONCLUSION.
This
worked very well.
There
are extra relays in the box to include two main “action” speeds…“Action” fast
and slow… this was to be sorted out by software.. was the roll (or pitch) changing at a fast rate, or slow rate??? And it would change to suit…. However I
never got them wired up as it didn’t seem to need it.
IF
I WERE TO BUILD THIS AGAIN ?
Wouldn’t
change anything…. Except do it more tidy J
Updated 1.1.06