Electronics > Electronics

H-bridge schematic review?

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ErikY:

--- Quote from: jwatte on January 16, 2013, 03:15:30 PM ---R1 and R5 (and their mirrors on the other side) are used to "default" the circuit to a known good state when power is being applied or removed.
The gate of MOSFET transistors are small capacitors, that can retain their last switched state for a long time, unless there is something for them to "bleed" that charge into if driving power is removed.



If you do not own a digital multi-meter, please buy one! A $20 Radio Shack one will probably do a good enough job. Typically you just need to measure voltage and resistance.


--- End quote ---


Got it, that makes sense, thanks for that explanation!

I actually do own two multimeters, I was just not smart enough to use it!

My DC motor was going forward with PWM working perfectly, and going reverse at just one speed, but going nonetheless.

I assumed (big mistake) that everything would be fine with the L.A., I will be sure to be much more careful in the future!

waltr:

--- Quote from: jwatte on January 15, 2013, 11:49:07 PM ---
--- Quote ---Their Drains should be to the +UB rail.
--- End quote ---

To clarify: The /actual/ drains should be towards the load.

Opps your right, brain glitch.
I'm correcting my post above to try and prevent future confusion.
--- End quote ---

waltr:
Some high wattage resistor are good substitutes for a motor when testing circuits like this. Then just put your voltmeter across this load resistor.

Switched connections, burned out parts. Yep, been there have some times still do that.

Nice you got this working.

ErikY:
Thanks much for your help guys, I appreciate it!

jwatte:

--- Quote ---I was just not smart enough to use it!
--- End quote ---

Good decisions come from experience.
Experience comes from bad decisions.

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