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

Brad Stewart EMAIL HIDDEN
Sat Apr 6 12:48:30 PDT 2013


It may not work due to several reasons.  Perhaps is as simple as not enough
gate/base drive current.  Does the collector/drain go to ground/vcc in each
direction?  If not, you have insufficient drive.  Which h-bridge are you
using?

Do you have a schematic?  Several H-bridges have over-current sensors which
will flag a stuck motor, which is preferable over using a relay or discrete
transistors.

 

Brad

 

 

From: EMAIL HIDDEN
[mailto:EMAIL HIDDEN] On Behalf
Of Cord Slatton
Sent: Saturday, April 06, 2013 10:02 AM
To: EMAIL HIDDEN
Subject: [EMS Discuss] HIgher current H-Bridge and circuit help

 

Hi all!

 

I hope someone may be able to help me to decide what direction to take a
project that semi-works but doesn't complete the goal set out.

 

I have a chicken door opening mechanism built using an electronic
screwdriver powered from 4 AA batteries, it has a spool on the driver area
and it winds up a rope that pulls up the door through a pulley system. The
switch on the screwdriver is a weird type that throws both negative and
positive at once and then reverses that for the other direction, thereby
avoiding the need for any IC or control. The way we operate it is to hold
the button while the door goes up or down and release it when it is in the
correct spot. This all works fine and has been in place for a while.

However now that it gets light earlier I have built a circuit that will
automatically open the door when it gets light. It uses an H-Bridge to
control the motor instead of the direct connection to the batteries as
before, which worked great in testing with a motor with no load on it,
however once I built it all and tried to put it in place the current of the
H-Bridge(600ma) was not enough to open the door at more than a snails pace.

My question is: should I continue to look for another higher amperage (to
let all the juice from the batteries through would be a much higher
amperage, like 1 amp)H-Bridge with a similar pinout layout or try to use
relays to switch it, or try to use some transistors to do it?

 

Thanks for any help!

 

Cord

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