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is the difference between switched and non switched BEC's
people are confused by BEC's at the best of times, and in particular
what the difference is between switched and unswitched BEC's.
a BEC is a Battery Eliminator Circuit (BEC) and was designed simply to
provide a fixed and lower voltage output from a higher input, without
needing to have a separate flight battery on board to supply the 5 volts
we need. Almost all Radio receivers today run at 5 volts, and some
will accept 6 volts as well. The problem is that some servos, especially
the higher priced ones, cannot accept 6 volts, so if you have a 6 volt
feed, you need to drop the power that goes to those types of servos or
they will burn out.
is where the BEC comes in for it's first task. All you need to do
is to cut the power lead that goes to the servo, and insert the BEC into
it. The signal cable is left alone.
of us avoid this and prefer to insert the BEC into the circuit
before the receiver so that the receiver runs at 5 volts. To do so we
take a positive and negative lead off the lipo before it reaches the
ESC, and we run the 5 volt BEC output to the BATTERY connector of the
receiver. Then we need to cut one or both of the power wires that
come from the ESC to the receiver to ensure that only the 5 volt supply
lets move to the question of plain and switched BEC's
part of the process of dropping the voltage, especially from the typical
11.1volt lipo that we run on 400-450 size helicopters, is that the BEC
generates heat, and it can be quite a large amount of heat. We can
of course position the BEC where it gets lots of cooling from the fan to
we get ourselves a switched BEC, which are typically more expensive, we
get a BEC that actually switches the input current on and off internally
millions of times a second, which helps a great deal to reduce the
amount of heat generated.
The BEC is
also used to allow us to use 4 cell, 14/8 volt lipos on our 11.1 volts
helicopters if we want to do so. It may seem strange, but quite
often we do want to do this to gain a bit more power to the motor, but
of course, still provide 5 volts to our radio receiver. If you
want to do this, check that your motor can take the additional voltage.
in future when you need a BEC, do yourself and your helicopter a favour
and get a switched one
I do hope this was useful. ?