Asked — Edited

Fuses, Power Protection For The Ezbv4

Hey guys, long time since I've been around. Just getting to fooling around with my EZBv4. Those are pretty harsh terms of marking a thread as a question! "Don't ask too many!" What's up with that?

But, to my question. I finally made the adapter plate to get the EZB onto my RoboPhilo frame, and now I'm wondering what and how to power everything. I found the thread about power supplies: which had a really helpful datasheet:, but I'm wondering about power protection.

Normally, when I'm working with DC it's in a vehicle or a rack and there is plenty of room for ATC fuses and fuse holders. There's not so much room in the RoboPhilo, and I don't think that would fit very well. What kinds of protections are available for robots this size? I don't think it would be a good idea to run the bot without one, though it seems the original controller didn't have any kind of fuse to it.

The RoboPhilo is a 24 DoF humanoid robot using old school analog servos, which I hear draw +-200ma of current. Most of the servos are SV4032's, and here's the product page: There are a couple of SV4140s:


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You might consider one of the polyswitch type protection devices:

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I am using a poly fuse from a dead 3d printer board. It is rated at about 20 amps, and is 1" x 5/8" x 1/16". I used it with a mini deans connector which goes directly into the EZB. I haven't had any problems.

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Hope this gives you more ideas and direction.

Ron R


Sounds like a polyfuse is the way to go. What's the difference between a polyfuse and a circuit breaker? They seem to operate the same.


The circuit breaker is a mechanical device that acts like an on/off switch and when operated to the off condition requires a physical action to be turned back on.

The polyswitch is electrical and when activated will open the circuit and then close the circuit when the initial cause is no longer present, after a timing interval of a few seconds or days depending on the type of polyswitch installed.


Guys, the EZBv4 has a giant polyfuse built-in, so I think I'm good. I didn't realize it when I asked this question.


Compact size (5cm x 5cm x 3cm)
200MHz 32-bit total processing (120 MHz 32-bit ARM Cortex-M3 processor & 80 MHz microchip PIC32)
Small size (2.1" x 2.2")
Wi-Fi connectivity (ad-hoc/infrastructure/WEP/WPA/WPA2)
Embedded web server
Energy efficient digital switching power supply
Resettable fuse protection
Reverse polarity protection
Amplified speaker for speech and music
8 x 5 volt tolerant analog (ADC) ports
24 x 5 volt tolerant digital ports (servos, PWM, and more)
Supports up to 73 servos (combining PWM and Dynamixel)
Dynamixel servo support
3 x I²C ports
1 x ezrobot video camera port
3 x high speed UART ports
Battery and temperature monitor