Re: NEW POWER SUPPLY That is the same thing, except much easier.  Plus we save donut money.  However,
we'd have to look at the effect of 7 volts reverse bias on the motor LED's.
Plus, we'd have to make real sure not to short the bent pin 8 to the socket
underneath it.  That would put 12 vlots on our 5 volt line with interesting
results.

Gary


Nick Taylor wrote:

> Great solution Gary!  How about just pulling the L293D/SN754410 from
> the U11 socket, bending pin-8 out and soldering the REALLY BIG battery
> positive lead to it, then soldering the negative lead to pin-1 without
> bending it out, and then reinstalling the chip.  It doesn't save much
> money since there wasn't much money involved, but it does save quite
> a bit of time.  Biggest benefit is that if you use the HB on more
> than one project, all that needs to be done to switch back and forth
> is to have an extra chip on hand ... swap the modified chip for the
> unmodified one.
>
> Your method provides and very easy way to change the driver chip to
> a much higher power chip such as the 298L.
>
>  - Nick -
>
> Gary Livick wrote:
> >
> > This was explained a week or two ago here on the list server.  Check back
> > and you'll find out what traces to cut, etc.
> >
> > However, I have found another way that is very simple, and does not require
> > you to make difficult-to-fix cuts on your boards.  Just add another 16 pin
> > socket onto the user area on your expansion board.  Remove one of the L293
> > chips and set it aside.  Use 20 ga solid hook-up wire, and take all the
> > signals, the 5v and ground line from the socket with the removed chip over
> > to the new socket.  You can push the wires into the socket at the old
> > location, and solder at the other socket.  Don't connect the motor leads
> > from the old socket to the new.  Instead, connect the motors you want to
> > use to the motor output ports on the new socket.  Bring the power leads
> > from your REALLY BIG battery to the new socket, and connect +12 to pin 8
> > and common to the board common (on the socket).  Plug the L293 into the new
> > socket and hang on, we're goin' places!
> >
> > I just did this, and it works great.  If you have the room for a seperate
> > board, you can build this up and include a charger plug-in same as what is
> > on the HandyBoard.  That way you can use the HandyBoard charger to charge
> > your 12 volt gel cell.  You can also hang lots of motor-direction LED's and
> > a charge light if you want.
> >
> > Total cost is less than two donuts.  Time is about two hours to wire up.
> >
> > Gary Livick


