How NOT to Build an H-Bridge Motor Controller
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- เผยแพร่เมื่อ 15 มิ.ย. 2016
- The internet is full of schematics. But be careful what you search for. Always double-check to make sure any given schematic matches your individual requirements or you might be in for a surprise.
- วิทยาศาสตร์และเทคโนโลยี
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Which software are you using for simulations?
This was better explained than any textbook I have encountered. Thank you
Thanks. I didn't realize this was starting to get some views. I should finish up with part 2 of this soon haha.
3:25 - "Just for demonstration purposes" - well then, their circuit demonstrates how to build a circuit that wants to be on fire.
Good design doesn't happen as an afterthought, it's built-in from the ground-up, and the people looking up these circuits, don't know what a good or bad circuit is.
Very glad you're teaching this series
While the audio could be a little better, the content is excellent. I really appreciate such a clear look at the problems of these online designs. I hate trying to filter through all the nonsense circuits to find ideas that work for my project. Thanks for the great content and I hope your channel is still active.
Fantastic, thanks for teaching us all that!
not to mention all those bridges with npn or pnp transistors have no protection diodes for the inductive load. this was a great video by the way now im off to watch the other one
it was a very good video, indeed most of practical (and very important) details are totally missing from textbooks or the internet. Waiting for the second video where you make on of those bridges succesfully
Great Video... Thanks bro
Nice video, thanks for sharing :)
I recently built my own H bridge motor controller and had the same problem you faced at the end of the video. Im trying not to use a H bridge IC since it'll be a good learning experience to design one that works myself xD.
Though this is a very good video(thumbs up), I strongly disagree on not building from scratch, because many users watching this video really need to understand the operation of diodes, RC timing, transistors, operational amplifiers and comparators. Without knowing the fundamentals of the aforementioned components they will go on a search for a "canned" product that doesn't do what they want. For example current sensing circuits, high side driving of N-Channel MOSFETs, HF interleaved boost converters, etc.. I encourage anyone who wishes to understand how controller ICs operate, to build similar circuits in simulation, using discretes, check your math then build them in reality. Another thing that should be mentioned that I don't see in most H bridge related videos, is that an H bridge can be used to in DC-DC conversion design, where the motor is replaced with the primary of the output transformer, using a different control scheme.
Yea I'm totally with you on that. I don't believe I advocated using a canned circuit. The point of this vid was to demonstrate the risks in doing so. In part 2, I show the process of building an H-bridge from scratch with a focus on design thinking.
Where is the flyback protection in the H-bridge circuit normally?
nice video
hey can we use the first schematic that u showed using pnp if we connect a resistor of 220 or 1 k ohm to each of the base to drive a small 9 v DC motor?? Please Reply soon THnx U hav a sub btw ;-)
You need to simulate all your circuits.
Seems like a fairly risky design. Think about what happens in that circuit if one of the inputs goes to high impedance. You're going to get current spikes during switching. But I don't know. Maybe it can be done. Simulate.
I have a part 2 of this video where I explain how to build an H-bridge. My suggestion is a little more complex than this, but its tried and tested (by me). Check it out.
Nice video. Would be great if there was away that you could boost the simulated circuits size to avoid having to magnify things at the viewer end.
would replacing transistors with MOSFETs solve the problem?
Yes, MOSFETs would work as long as the off input state is equal to 0V/GND (not high impedance).
What is the simulation software that is being used in the video?
www.falstad.com/circuit/
@@JoshSideris ty
Hey thank I got same problem as you got me 4 day to figure it out its better and cheaper to buy the IC xD
"There is no switch". Add one😂
great video, very educational and bad ass :) but thats not the important reason.
The problem I see is these basic circuits work, but you need to take in to account for your specific application, no one circuit fits all..
Use mosfet not transistors then it will work
Yep. They should have used mosfets.
this is just a snippit from an entire circuit, I imagine the current limiting is done before the input, and not relavant to the operation of the h-bridge. Not to mention the falstad site seems to always assume the perfect power supply, which does not exist. I really don't know why you expect them to add the current limiting circuitry to an h-bridge tutorial since it would distract from the lesson itself. If you implement it in fastad with proper current limiting and base resistors, there seems to be no problem for me.
Are you referring to Sparkfun's circuit? What do you mean by current limiting? You mean on VCC? Current limiting on an H-bridge only protects your power supply from stall conditions, it has nothing to do with normal H-bridge operation. I built this circuit in Falstad with base resistors to check your claim that it works. It doesn't. tinyurl.com/yddwc8d4
vcc in for example does not neccesarily mean straight from the supply. limit the current comming in from vcc even with a resistor, and the circuit works out just fine.
goo.gl/7ZyVYD
I am sure there are much better ways to illustrate this, but you would never have no resistance through transistors coming from a power supply, so I don't understand why you are showing the circuit as such.
That last link was bad, because I am special and did not use the proper method. but here is a better link to how you would actually do it tinyurl.com/ybppxk59
and I will return with the way I tried to link moments ago.
Edit: proper link to proper orientation of mosfets, because I just can't seem to handle copy pasting properly today with so many circuits open.
tinyurl.com/ybvokupz
That is yours with easy adjustable voltage input for the transistors, and teh transistors spots have been swapped, and there is no resistance on incomming vcc, the load does all the resisting. Seems you were looking at some bunk charts.
Okay, but all this does is put VCC through a 100 ohm resistor. That still doesn't resolve the problems with this circuit. tinyurl.com/y9fs3rve
Note that in this simulation, only 23.2% of VCC is being dropped over the motor. The rest is being wasted.
Whoo hoo, finally got the next video out! Enjoy: th-cam.com/video/4y2kPmxW-xk/w-d-xo.html