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DPRG: GARP motor controller design

Subject: DPRG: GARP motor controller design
From: Roger Arrick rarrick at ix.netcom.com
Date: Tue Jun 17 13:05:58 CDT 1997

>Eric wrote:
>                                               V+ (50V max)        V+
>                                               .                   .
>                                        1K     |                   |
>                                    +--/\/\/---+                   |
>                                    |          |                ------
>                                    |          |                 Load
>                                    |      +---+                ------
>                                    |     /                        |
>                             1K     |   |V_                        |
>                        +---/\/\/---+---|   2N3906               |_|D
>                        |               |\         100 Ohm    G| 
>               10K    |/                  `----+---/\/\/---+---| |-. 
IRFZ44
>   +5V=on  ---/\/\/---|  2N3904                |           |      _|
>                      |\                1K     |           |     | |S
>                        v         +----/\/\/---+           |       |
>                        |         |                 100K   |       |
>                        +---------+----------------/\/\/---+       |
>                                  |                                |
>                                  |                                |
>                                 ===                              ===
>                                  =                                =


To make an hbridge, you'll need P channels to do the top side switches 
Or you'll need a V+ that is 10v above the battery voltage to turn on an 
N channel up there.  Polarity of the turn on is also an issue.  You'll 
need a circuit to prevent tops or bottoms from turning on together and
making a toaster.

I like using an LM324 op amp or a 4049 hex inverter to turn on the Fets 
instead of descrete transistors and providing the level conversion.

Roger.

- -- 

     /--------------------------/---------------------------/
    /       Roger Arrick       /     Arrick Robotics       /
   /    roger at robotics.com    /       P.O. Box 1574       /
  /     Ph: (817) 571-4528   /   Hurst, Texas 76053 USA  /
 /     fax: (817) 571-2317  /   http://www.robotics.com /
/--------------------------/---------------------------/

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