static electricty and burned out components

Interested in Robotics? Here's the place to be.
Post Reply
stampee
Posts: 5
Joined: Wed Oct 13, 2004 1:01 am
Contact:

static electricty and burned out components

Post by stampee » Sat Feb 28, 2015 7:25 am

Hello: I have an R2D2 robot I built many years ago, that I am having problems with electronics burning out. I am guessing it is caused by static electricity but I am not certain.
Last year I burned out my easyVr voice board and the atom microprocessor and I have no idea why.
recently,I lost my left drive motor, for unknown reasons and while working on the robot, yesterday I burned out my Lynxmotion ps2 wireless controller.
I do have 3 capacitors tied across the drive motors, so I presume that is good enough, but...
I am thinking I am getting static electricity into the electronics while I work on the robot and burning out these parts. Needless to say it can become expensive and is very frustrating.
I know of precautions to take like static mats etc, but I think it is getting directly into the circuitry somehow.
Can anyone point me to circuits that will help block or prevent voltage spikes and surges that may be causing this?
Currently I have a 1600 mfd capacitor tied across my 5V regulator output. But as I say this has not helped.

Specifically what happened yesterday is I was running the robot off my 12V wall power supply while working on the motor problem and I found out it did not have enough amperage to run the drive motors, so I connected the main 12V battery and instantly burned out the PS2 controller. I cant imagine why? both power supplies are 12V and the electronics run on 5v from the regulator, so I cant imagine why any surge got through the system. Also for years I have run both main and battery power connected without any problems. so, I really do not know what caused the recent failure, I am grasping at straws.
Any advice would be appreciated.
-Stampee

cae2100
Posts: 67
Joined: Tue Dec 18, 2012 4:40 pm
Contact:

Re: static electricty and burned out components

Post by cae2100 » Sat Feb 28, 2015 11:23 pm

are the motor controllers and such homemade or is it store bought? If it's homemade, you may have forgotten to include the clampping diodes on the motor driver circuitry, which the flyback voltages from the motors would be causing voltage spikes in the hundreds or thousands of volts, which will wreak havoc on your electronics pretty quickly.

dyarker
Posts: 1640
Joined: Fri Aug 22, 2003 1:01 am
Location: (somewhere), Afghanistan; from Rochester, NY
Contact:

Re: static electricty and burned out components

Post by dyarker » Sun Mar 01, 2015 5:20 am

Motors aren't likely burnt out by static. A stalled (stuck so it can't turn) motor with full full power applied will burn out.

Static may have caused some of the other problems. Are there symptoms of static? Like sprarks from your fingers to light switches.

Do you have a UL approved grounded anti-static mat on the workbench? With robot on the mat, you touch the mat before touching inside the robot.
Dale Y

cae2100
Posts: 67
Joined: Tue Dec 18, 2012 4:40 pm
Contact:

Re: static electricty and burned out components

Post by cae2100 » Sun Mar 01, 2015 10:12 pm

oh, if your burning out motors, then you might want to turn the current going to them, or control them through pwm. Also, what voltages are you sending into them and what is the motors rated for? Those two things will burn out motors faster than anything.

Also, in the case of when you plugged in the battery, I would check the voltages on the battery. it might be a 12v battery, they usually put out 13.8V, and the inrush current from the battery might wreak havoc, but that isnt an issue if you have a regulator going to the stuff. The general voltages for ps2 controllers isnt 12v usually, It's 7.5v I believe, so that could be why you cooked it. It does seem to work good if you run it off of the 5v supply, Ive done that with my PIC projects that used the ps2 controller.

stampee
Posts: 5
Joined: Wed Oct 13, 2004 1:01 am
Contact:

Re: static electricty and burned out components

Post by stampee » Mon Mar 02, 2015 7:51 am

Thanks to everyone. I found out the motor and control circuit was not burned out. The basic atom pin that does HPWM had burned out. However I am back to why this is happening.
I see no obvious sparks jumping like true static electricity would be.
I am using the lmd18200 motor controller which has flyback protection inside. My wall power supply did not have a ground wire, its only a 2 wire power supply so there may be problems there. I also saw that it puts out 14.4 volts no load. However I only use the 12V for motor power. I regulate it down to 5V with an lm385 regulator. I then have the 1600 mfd cap across the 5v output. I will now start using a desktop power supply instead.
No I did not have the static mat in use this time. I was kneeling on the wooden floor working on the robot. (It is to large and heavy to get onto a bench)
But it is possible I had static charge on my body.
It seems odd that plugging in the 12V gel cell would put any surge into the electronics however. And why didnt the 5v regulator clamp out any surge anyways?
Also what initially caused the microcontroller pin to burn out? (basic atom 40)
My last use of the robot, I drove him to the car fine, then lifted him into the car.
3 days ago I installed the battery and the left motor was dead. So... did he get fried somehow just sitting around?
I had an idea that when I drag him, his wheel motors turn. So they generate electricity I presume when they rotate. Maybe they create some odd surge voltage that the 5v regulator cannot dump fast enough? I do have a switch on the wheel motors, but It was installed for testing purposes. I never thought to shut the switch off when dragging the robot around. and cant say if it was off or on at the time. BUT is this a problem anyways?
What I was hoping for would be some circuit that would help prevent any user stupidity that I may cause such as static on my body.
You should also know that taking the robot to shows, installing the gell cell. Powering it up in my own costume etc. It really is not feasible to be worrying about any static charge on myself at the time.
We certainly do not worry about this with our TV's and smart phones, radios and millions of other electronic devices.
Once again. please note. I do not know if it was a static problem. I am just grasping at straws.
Thank you so much for the ideas.
-Stampee

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests