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Re: Amp + Filter sensor circuits

On Tue, Jan 18, 2000 at 10:37:30AM -0500, Joyce Poon wrote:
> When do you think it'll be a good time to meet?  We also have to take
> care of the H-bridge. I want to go do some extra physics on Wed.  Maybe
> Wed afternoon?  Or later tonight (after 8)?  

If you think it's necessary for us to meet, choose a time.  There's
nothing I need to discuss immediately.

Here's our current standing:

1) H-Bridge

   Malone acknowledged that large voltage losses are indeed often a
   problem with the H-Bridges, especially when driving large currents for
   large motors.  His suggestion was to use a Darlington-pair transistor
   to turn the motor on and off, but to use a relay to choose the
   direction of the motor.  He suggested that doing this will also enable
   us to spend more money to buy a higher-quality transistor (ie. one
   with a lower voltage drop).

   Joyce: I'll try calling you after my 3-5 class today.  I seem to remember
   that both Active Surplus and Supremetronic are still open at that
   time.  If you know what type of relay we need, I can probably pick one

2) Comp

   The comp board appears to work.  I had the 6522 sockets backwards
   (that's what I get for soldering those at 3am in the morning) and may
   have destroyed one of Malone's 6522s because of that (oops), but the
   6522 appears to work still.  I don't think it's damaged.  Malone needs
   to produce a modification for the boards to work with the WD chips
   he's giving us.  The first such modifications will be available on
   Thursday, and handed-out on a first-come, first-serve basis (I already
   have a "first-serve" reservation for us).  

   I'll post the usual statement of intent for Thursday's lab later
   (Wednesday night).  It'll depend somewhat on what Joyce plans to do
   with her motor control circuit.

   Somehow I've gotten one of the wrong chips in the board.  Joyce?
   Do you have a 74hc74 chip in your plastic box?  I had a 74ls47 plugged
   into the socket where a 74hc74 belonged...  Needless to say, this
   caused some small problems...  :)  Hopefully the correct 7474 is in
   your box somewhere.  Otherwise we'll need to buy another from
   Active.  The board was tested using one of Malone's 74hc74s.

   The ground pins of the 74ls47 weren't connected so Malone thinks it
   should still work.

3) EM

   Battery supply question still up-in-the-air pending resolution of
   the H-Bridge problem.

   If Cindy needs something at Active Surplus for Thursday, she is
   advised to state her needs now.

Signature withheld by request of author.