Model Boat Mayhem
Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: sunnydog on January 22, 2008, 01:27:01 am
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when using an ESC in a BEC set up, into which socket on the Rx is the ESC pluged.
i have a 4 chanel Rx with BEC. they are labeled as follows-
BAT
Ch1
cH2
cH3
cH4
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The ESC is plugged into the throttle socket on your receiver, which ever one that happens to be. Futaba tend to number the sockets on the Rx, so I normally scratch a letter in the plastic alongside the socket with a "T" for throttle or "R" for rudder etc to avoid confusion as to which number socket is which function. The manual for your system should explain the socket functions, or you can connect a servo and work it out for yourself.
Peter.
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thanks for that pete
i am looking at the moment, to find a manual (acoms techniplus 4 40 MHz ) seems to be like trying to find hens teeth.
pretty new to this. i like to think i'am better at the mechanical side than the electronic side.
found it easy to build the boat but batteries and amps and all that stuff are a new learning curve, but it's better to ask
cheers
jerry
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Sorry, just wrote a load of c**p. O0
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the BATT socket is only really needed if you are running becless esc's (Electronize) or servo-operated resistance coil types, (bobs boards), esc's can go into ANY socket just a case of how you want your model set up
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esc's can go into ANY socket just a case of how you want your model set up
.......but it's quite useful to use the socket which is controlled by the signal from the throttle stick............... ;)
Funny, but of all the subjects which cause confusion to my customers, the use of BECs puzzles far more than anything else.
FLJ
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Am I correct in saying that the BEC is a 5 volt source only, and it is used to power up the receiver ?
Therefore it's best to get it from the best source, ie, a good speed controller, and that it is fed to the centre pin of the three wire plug ? I assume then that the centre pins of all the sockets on the Receiver are joined together, so any socket will do.
The main reason for disconnecting all the other BEC lines is a clash of voltages from different sources.
Ken
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Am I correct in saying that the BEC is a 5 volt source only, and it is used to power up the receiver ?
Therefore it's best to get it from the best source, ie, a good speed controller, and that it is fed to the centre pin of the three wire plug ? I assume then that the centre pins of all the sockets on the Receiver are joined together, so any socket will do.
The main reason for disconnecting all the other BEC lines is a clash of voltages from different sources.
Ken
Well, not quite, Ken.........
The BEC (Battery Eliminator Circuit) is usually based on a small semiconductor called a regulator. This has the voltage from the main drive battery applied across its input and ground connections, whereupon it gives forth with a lower voltage across its output and ground connections. The "spare" is dissipated as heat through the metal tab. There are a couple of capacitors in there to calm things down, and that's about it. The most useful type of regulator is a "low drop-out" type, which only requires an input voltage of about 0.5v higher than the output one. If your BEC doesn't have that then you'll need a supply of at least 2v higher than the required output. (I hope you're taking notes; there's a short written exam at the end.... ;)). If the input voltage drops below the threshold voltage required by the regulator then the BEC stops............dead. This can cause problems unless you keep the main drive battery well charged up.
The centre connection of a three-wire system is USUALLY the battery Positive, although there are some systems which have a Negative centre pin. The White or Yellow wire is the the one which carries the signal pulses to the servos, ESCs etc so they have to be separate. It's the Red and Black pins which are common to all Rx outputs.
A speed controller doesn't have to have BEC to be any good. In my experience that's the bit that causes the most problems, in so far as often you can't see just from looking at it whether or not an ESC has BEC fitted and, even if it is clear, you can't see whether or not it's ON or OFF. IMHO it's better to have a separate BEC unit so at least you can see it's there. That way if you don't want BEC then simply don't fit one in circuit - easier and less mind-numbing than having to pull little sockets out of plug shells to disable the thing.
You were about right about the voltage clash, though............. O0
FLJ
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Just to re-iterate some points and add some more....
BECs are usually linear regulators so they will generate heat depending on the load and the supply voltage. The more load or the higher the supply the more heat that is generated. On 12V systems for every Watt delivered by the BEC it dissipates 1.4W. On 24V that is closer to 4W.
If you connect up the outputs of multiple BECs you are asking for trouble - the outputs are never the same and the highest ones will pump current into the lower ones causing lots of heat generation.
BECs installed on ESCs are useful - but it is not the best place to have it. Essentially the supply can be quite dirty because the noise from the motor is imposed on it and this can break through to the reciever. Better to have a separate BEC with a pair of dedicated wires going to the the battery. IMHO at least.
Wom
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I'm learning all the time. Thanks guys O0
Ken