Re: controlling dc motor direction (help a newbie, please)

On Fri, 27 Oct 2006 23:09:33 -0700, theneonlobster@xxxxxxxxx wrote:

i have a 1.5-3vdc motor that i would like to turn on and off in
opposite directions using two microswitches. i'm new to electronics,
but from what i've learned so far, i think i want to use a 556 timer
and dpdt relay. striking a switch would turn on the 556 timer for x
seconds (5, i'm thinking), then the dpdt relay, then the motor. am i
right taking this direction?

Pretty much, but I think you'll need more than just a 556 and one
relay. You'll need at least two - one for "on/off" and one for direction.
And each of them will need a driver transistor, snubber diode, and so on.

also, would striking the other switch before the end of the process
cause a problem? i'm hoping that it wouldn't interrupt the motion, and
would like to know if i could have it be ignored by the circuit.

Actually, it depends on what kind of circuit you build. What I envision
is the two sections of the 556, each being triggered by its own
microswitch, with the output of one going to the "reverse" relay and
the outputs of both "OR"ed together for the "ON" relay. In that case,
if it's going in reverse and you push the forward button, it will
start the forward timing cycle, so when the other timer times out,
the reversing relay will drop out, and try to instantly reverse the
motor. If it's going forward and you press the "reverse" button, it
will immediately try to reverse the motor.

So you'd need to come up with some kind of trigger lock-out while
the motor is running.

Good Luck!
Rich

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