It is a simple project - a focus system for a taken lens and anamorphic adaptor. I have three pots. The first one I use as a manipulator. The second is used to get the position of the continuous rotation servo motor#1. The third pot is used to control the position of the other continuous rotation servo - motor#2. Motor#1 rotates the taken lens and motor#2 rotates the adaptor.
I use an AOZ1014AI to step down a 7.4V Li-ion battery to 6.5V. First I used two 360-modified JX DC6015(4.8V-6.6V) servos. It worked ok for a minute and then motor#2 burnt. Next I tried Doman servo (4.8-7.2V). This time motor#1 burnt.
Is it ok to connect two servos to one source in parallel?
Yes, it is OK to supply multiple servos from the same power source. That power source should have capacity for both servos.
But if the motors burnt out in the servos, that is not a power supply problem.
Did you stall the motors and leave them stalled? As in, command the servo to move to a position, but put a load that the servo cannot move on the servo output. This will burn out any servo.
How much physical force does it take to move the lens and adapter? Are there any hard stops that your servos might be trying to run past?
Did you build that buck converter yourself? Building a buck converter is a highly skilled task, you don’t just slap components down on a Solderless breadboard, you need a well designed PCB. You also need an inductor that can handle the frequency and the flux density.
There are a lot of crap modules out there that simply don’t work at the current you need to drive two servos.
They are burnt. JX 6015 - one of the chips has burnt both with wires. Also if you connect 5V directly to the motor it can move only CW. Doman - electronics looks ok, but the motor now have a wide dead zone - seems like on of the coils is dead.
As for the servos. It worked ok with 5.7V AC-DC power supply. AOZ board killed it.
As for AOZ - yes I've done it. But I used an xls file from the supplier. It calculates all the components' values. I've printed a board according to all tips from the datasheet. The board works ok, but it seems when servos are connected it goes crazy. On one of the forums there was s thought that I'm getting overvoltage due to the regenerative energy when I slow or stop my motors. This buck can't sink current, and even if it could it may pump up the input cap until the IC fails.
Which modules are crap? All of them I've chosen according to the supplier's calculation file.
How do you control the "position" of a continuous rotation servo? AFAIK all you can control is the speed of rotation. And if you don't get the centre/stop position calibrated exactly right you're very likely to burn them out.
Easy. I have two pots connected to arduino, that tells me where the servo is) 1500us stops the servo, you can control speed and direction and it is enough to control it.
As for AOZ - yes I've done it. But I used an xls file from the supplier. It calculates all the components' values. I've printed a board according to all tips from the datasheet. The board works ok, but it seems when servos are connected it goes crazy.
As mythbusters say ..... well, there's ur problem. If your servos are connected, and the board 'goes crazy', then your board isn't working ok, especially when you later mention that your motor systems work properly with a different supply.
When you mean 'works ok', what kind of tests did you do to indicate ok? Could put on a dummy load (suitable resistive load that can handle the power) or something to see whether it does what it is meant to do.
Tofer:
First I used two 360-modified JX DC6015(4.8V-6.6V) servos. It worked ok for a minute and then motor#2 burnt. Next I tried Doman servo (4.8-7.2V). This time motor#1 burnt.
Are you saying that you had/have 3 servos ---- two JX DC6015 ones... motor #1 and motor #2, and the other one is a doman one... motor #3?
Tofer:
As for AOZ - yes I've done it. But I used an xls file from the supplier. It calculates all the components' values. I've printed a board according to all tips from the datasheet. The board works ok, but it seems when servos are connected it goes crazy. On one of the forums there was s thought that I'm getting overvoltage due to the regenerative energy when I slow or stop my motors. This buck can't sink current, and even if it could it may pump up the input cap until the IC fails.
Got a 'scope? Probably the only way to see whats really happening. I presume the datasheet recommended
layout was used?
On one of the forums there was s thought that I'm getting overvoltage due to the regenerative energy when I slow or stop my motors. This buck can't sink current, and even if it could it may pump up the input cap until the IC fails.
Crap.
It fails because the layout is poor. I have never seen a professional power supply engineer that could make a good layout first time, normally two or three iterations are needed. They work fine with low current but can oscillate with the full output voltage at specific currents. This could also be just at some value of high current.
Which modules are crap? All of them I've chosen according to the supplier's calculation file.
All the cheap ones on eBay are crap. Suppliers there lie, and are deliberately obscure. A favourite trick is to give a voltage rating and a current rating which the module can reach, but they neglect to say it is not at the same time.
