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Author Topic: H-Bridge for Wally the Wall bot  (Read 780 times)

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Offline ConscriptedTopic starter

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H-Bridge for Wally the Wall bot
« on: September 23, 2012, 08:40:41 AM »
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. 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
« Last Edit: September 23, 2012, 01:05:35 PM by Conscripted »

Offline waltr

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Re: H-Bridge for Wally the Wall bot
« Reply #1 on: September 23, 2012, 05:18:21 PM »
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.

Offline Soeren

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Re: H-Bridge for Wally the Wall bot
« Reply #2 on: September 24, 2012, 12:14:21 PM »
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 :)
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline ConscriptedTopic starter

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Re: H-Bridge for Wally the Wall bot
« Reply #3 on: September 24, 2012, 12:29:36 PM »
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

Offline waltr

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Re: H-Bridge for Wally the Wall bot
« Reply #4 on: September 24, 2012, 07:56:21 PM »
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.

 


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