Put a 1k resistor across where the motor would normally connect. Then read the voltage drop across it. Without a load, the high input impedance of a meter can show a voltage that is "parasitic", e.g. not able to actually source current.

You should be able to determine the current and direction then using Ohm's law with a resistor as the motor (drawing much less current).

The protection from shoot through is dead time to ensure one switch is off before turning the other one on. Adding a capacitor to the power supply only stabilizes the power, and would be discharged when the power rail is shorted.

The Relays will work, but only for forward/reverse, not PWM/speed control. If you read the datasheet linked above, most of your questions are answered within it.

 

Put a 1k resistor across where the motor would normally connect. Then read the voltage drop across it. Without a load, the high input impedance of a meter can show a voltage that is "parasitic", e.g. not able to actually source current.

You should be able to determine the current and direction then using Ohm's law with a resistor as the motor (drawing much less current).

The protection from shoot through is dead time to ensure one switch is off before turning the other one on. Adding a capacitor to the power supply only stabilizes the power, and would be discharged when the power rail is shorted.

The Relays will work, but only for forward/reverse, not PWM/speed control. If you read the datasheet linked above, most of your questions are answered within it.

To use the resistor voltage method would the schematic look like this http://switchit001.com/resistor_volts.png? Right now I'm measuring +.1V or -.1V (without any resistors) when the system is on, that seems somewhat low even with the meters, but I'll try it with the resistor method also to see what it is.


If the system is set up correctly, the dead time will take care of potential shoot through, but if something is wired wrong there is still a possibility of a shoot through. Ideally nothing will be wired wrong, but it can't hurt to have a safety precaution if it is.

 

Just add a 10 amp fuse to the power rail if you don't have a current limiting supply to test with.

That is a large enough value to allow function, but low enough that it will blow before damage to parts occurs if something isn't wired correctly.

The best thing I would suggest is to follow the original schematic, if it was posted as "tested and working", after hooking everything up, go back with a multimeter and verify all of your connections. Then apply power, with the fuse (switch fuse to 30A slow blow for regular use if desired).

 

Just add a 10 amp fuse to the power rail if you don't have a current limiting supply to test with.

That is a large enough value to allow function, but low enough that it will blow before damage to parts occurs if something isn't wired correctly.

The best thing I would suggest is to follow the original schematic, if it was posted as "tested and working", after hooking everything up, go back with a multimeter and verify all of your connections. Then apply power, with the fuse (switch fuse to 30A slow blow for regular use if desired).

Replacing the 2nd volt meter with a 10amp fuse worked like a charm. I am now getting the full +/- 19V (My power source should be 18V, but it tends to supply a bit more). There is one part that seems to come loose occasionally, but I think I can make it more secure by changing the wiring to it.

Tomorrow I will work on slowly increasing the amperage until i get to the full 30.

 

Ok, so today I attached the motor without a load to the H-Bridge to see if it could support it. The problem is the motor does not seem to be getting enough amps to turn on at all. Can an H-Bridge limit amps? My understanding was it would just blow up if too many amps went through it. Also I connected the motor directly to the power source and it worked fine so I know the H-Bridge it the source of the problem.

 

Post a schematic that reflects exactly how everything is hooked together right now, updated component values, anything else added or changed, etc.

Are you giving the +5v input to the h-Bridge to tell the motor to go foward?