Ok, I’ve got some interesting little DC Gearmotors for taking in dollar bills from a vending machine. Dual output shafts …but not much torque at 6V when running them through servo guts (servo circuit board)
My question is about using BEC (battery elimination circuitry) speed controllers with this microcontroller.
The manual is confusing me. I have the blue shorting block across VSRV=VIN in order to power the whole thing from one power supply.
Now if I use a BEC speed controller on one or more channels, do I still need a power supply hooked up to the servo power pins?
Will there be the lovely smell of frying wire insulation and another order for a microcontroller? Enquiring minds want to know.
To avoid the smell of burning insulation, you need to do two things:
- Do not connect multiple power supplies together.
- Stay within the recommended voltage range for the Maestro’s Vin (5-16V).
A single BEC speed controller could provide both Vsrv (for servos) and Vin (for the Maestro’s logic). However, if you do that, straining servos could cause the BEC voltage do drop below 5V, causing the Maestro to reset. Connecting the battery directly to Vin (with NO Vsrv=Vin jumper) would provide more reliable power.
Connecting the power from multiple BEC speed controllers together sounds like a bad idea unless the controllers explicitly recommend it. However, you could leave the power pins disconnected or power multiple banks of servos separately with separate BECs by cutting the power trace where indicated here.
Oops, I just realized I did not explicitly answer your first question: do not connect the BEC power to a separate power supply through the servo pins. All of the servo pins are connected together, and doing so would create a short circuit.
So, could i just cut the + wire from the speed controllers and attach the ground and signal to the servo pins…then use a traditional 6V power supply on the power pins and a separate higher voltage supply for the motor/speed controller combo?
What I am trying to accomplish is controlling higher voltage dc gearmotors …say up to 12V from the servo pins. These are not large motors…still in the small range.
The problem is I need the PWM circuit in the line somewhere to have the proportional forward reverse speed control. (everything i am using at this point is continuous rotation). Servo circuit boards won’t take that kind of voltage (at least not for long)
There are three things in your system that need power: Maestro, servos, and the speed controllers.
Suppose you have a 12V battery. I suggest the following power sources:
Maestro: battery (connected to Vin).
Speed controllers: battery.
Servos: BEC from one of the speed controllers (on the servo power pins).
Does that make sense? I am not sure why you want an extra 6V power supply if you already have a BEC.
Ok, I am more confused than ever, but that’s not unusual.
With a BEC speed controller, you have one 3 wire connector which powers the entire receiver and handles the signal for a specific channel.
So, lets say I have the jumper in place to power the board and servo pins from one source. I plug the BEC speed control into channel 0. Now, all 12 sets of servo pins are getting +5V right?..but there are no wires on the dedicated servo power pins…so is the board getting +5V at this point?
You see where I am coming from? I don’t have a separate connector for the dedicated servo power pins. The BEC eliminates that by powering all of the positive servo pins from that channel connection (i think).
It seems like I am making this harder than it needs to be, but I just want to be sure I don’t have redundant power input that can cook something.
i guess what my question boils down to is: If I have power to any channel…will that power all of positive servo pins and the board if the jumper is in place and there is nothing on the dedicated servo power pins.
I know that if I would do additional BEC controllers I would need to cut the positive wire and just have one BEC for power…but it is just the initial one battery set up I am trying to get straight here.
I am not sure what you are confused about. If you just have a single BEC connected by a single connection to the Maestro, and that is your only source of power, how could there possibly be anything redundant?
The servo power pins are all connected to each other and nothing else. If you install the jumper, they are also connected to Vin. But I was recommending that you NOT use the jumper and instead supply Vin directly from your battery. Does that make it clear?