[EMS Discuss] Higher current H-Bridge and circuit help

Brad Stewart EMAIL HIDDEN
Sun Apr 7 12:02:29 PDT 2013


 

The L193D should be adequate to drive your motor.  It has max of 1.2A on
peak current.

I think you need to ground pins 4,5,12, and 13.  You only have pin 4
grounded.

You may also need to check that pin 1 goes high as well.

 

If this doesn't fix the problem, then look at your control inputs on pins 2
and 7.  When the motor is engaged either forward or backwards, make sure the
pulses are held in their respective state and not oscillating.  Also make
sure they go from 0 to 6V.  You'll need an oscilloscope to check this.  

See the truth table below.  

 

Check your VCC2 voltage to see that it doesn't drop excessively.  A bulk cap
(100uF) may be necessary if the batteries are located at a distance.

 

Also, look to see if the internal diodes suppress inductive spikes.
Otherwise, I recommend using the diodes to suppress inductive spikes.
1N4001 are good enough.

 

Brad



 

From: EMAIL HIDDEN
[mailto:EMAIL HIDDEN] On Behalf
Of Cord Slatton
Sent: Saturday, April 06, 2013 11:20 PM
To: Greg Norman
Cc: EMAIL HIDDEN
Subject: Re: [EMS Discuss] Higher current H-Bridge and circuit help

 

I have attached a drawing of my chicken opening circuit, the only change I
made from this to the final version was switching the 2 discrete 555 timers
to a single 556 dual timer chip.

 

 
<https://docs.google.com/file/d/0ByOy0YDBXjt4Y2xUQ1ltWTgybGc/edit?usp=drive_
web>  chicken-door-circuit.pdf

 

The H-Bridge I am currently using in the circuit is a L293D

 

On Sat, Apr 6, 2013 at 5:38 PM, Greg Norman <EMAIL HIDDEN> wrote:

I did the exact same thing with a screw driver motor to open
a duck pen using a screw driver and one DPDT relay and one
SPDT relay. Exactly like Taper describes. I drove them with
a transistor. The DPDT relay controls direction and the SPDT
enables the motor movement. Here is the circuit I used. I
only drew the DPDT relay.

Greg

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