Adopted a h bridge here and facing issues

Community General Discussions
1

Hi all,

ages ago I found oddbots cool h-bridge on this page which works quite well. I started with 100x160mm boards and made two boards for two bridges in order to controll 2x2 motors.

A few weeks ago I got into contact with the pcb-tool Eagle and gave it a try to place two h bridges on one board 100x80mm (freeware edition).

As far as I can see I just copied the bridges. The only think that differs from the two-board version is, that I used the same power/gnd traces for both bridges.

Now I´m facing the problem that the Pins for the P-Channel mosfets respond to the Inputs but all the pins (2x2) for N-Channel mosfets remain at 0.08v.

I´m already looking for the problem for 2 days but can´t find it. Could someone probably help me?

Here is Oddbots H bridge.

https://www.robotshop.com/letsmakerobots/making-fet-h-bridge-revised

This here is my Eagle schematic.

 

hbridge_01_broken.png

I left out the current sensing part. Does anyone know why the N-Channel pins remain low? The N-Channel pins are the four bottom pins.

Any help is greatly appreciated.

 

 

2

I don’t see the FETs in your
I don’t see the FETs in your schematic. Where OB1 has the FETs you seem to have jumpers (JP6-JP8, JP10 and JP15-18).

This may be my misunderstanding of something. I’m not good at power electronics.