Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: Conscripted on September 23, 2012, 08:40:41 AM
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Good morning all.
I recently purchased the book "Arduino Robotics". Chapter 5 has a bot called "Wally the Wall-bot" that I'm interested in building. I was hoping some one here has already built the h-bridge. I would hate to purchase the parts, put it together and then spend a bunch of time debugging the circuit if it's a poor design.
I found a digital version of the schematic HERE (http://books.google.com/books?id=tBdKnLcf2oEC&pg=PA173&lpg=PA173&dq=wally+h-bridge&source=bl&ots=eT5bm9fkG-&sig=lsKUFVmT2Uj4L4zBrgIyV4Ayr6o&hl=en&sa=X&ei=2FpfUJS2G4XD2QWntYHADQ&ved=0CCcQ6AEwAA#v=onepage&q=wally%20h-bridge&f=false). The page with the schematic says "175"
The circuit uses - (4) 2n7000 - logic level N channel mosfet
- (4) FQP50N06L - N channel power mosfet
- (4) FQP4706 - P channel power mosfet
- (2) TC4427 - MOSFET driver
- (4) 10k resistor
- (4) 150-ohm resistor
The H-Bridge is stated to work at 18VDC, 5A continuous, and PWM at 32KHz.
Does anyone have any experience with this circuit?
Thanks.
Conscripted
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That H-bridge circuit is isn't too bad.
The major issue I have with it that both the low and high MOSFETs could be turned on at the same time. I call this the "Smoke' condition since it produces a short circuit.
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Hi,
There's the possble current shoot-through as waltr mentioned and it strikes me as very odd and inconsequent using a MOSFET driver for just the low side and discretes (of a lower current handling capability) for the high side - I don't believe it's made by a pro.
Apart from that, it should work if controlled correctly :)
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Thank you both for your input. I was pricing the parts out and it looks like it will cost me about $25 plus shipping. Do you know of a better design that is comperable in price and specs?
Conscripted
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1- look up Soeren's posts. He his posted schematics of H-bridges in the past.
2- With all of the integrated H-bridge chip available I haven't build a discrete H-bridge in many years. Search through threads here on H-bridges for some suggestions.
Also, google will help find others.