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

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?

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.

and, testing the motor speed, i've been using resistors to get my 9v
supply down to 1.5 and 3vdc. would i still go that route to control
motor speed, or is there another option?

and help would be appreciated. thanks

david

View in courier font:


+3 ----+ +------+-----------------------------+
| | | |
|>| | +---+
Rrly-1 | |
n/o +---v n/o n/c v Drly-2
--------[Motor]--------
Drly-1 ^ n/c n/o ^---+
| |
+---+ |
| |
Gnd -------------+-----------------------------+



Rrly = Run relay - energize it when you want the motor to
run. It is a single pole relay

Drly = direction relay. Energize or de-energize to change
direction. It is a double pole, double throw relay and
contains 2 sets of contacts, labeled Drly-1 and Drly-2.

Both relays are shown in the enrgized position. +3 gets
to the top of the motor through the energized Rrly-1 and
Drly-1 n/o and common points. Gnd gets to the bottom of
the motor through the Drly-2 n/o and common point. When
you de-energize Drly, Gnd gets to the top of the motor
through the Drly-1 n/c and common point. + 3 gets to the
bottom of the motor through the Drly-2 n/c and common
point, and the Rrly-1 n/o and common point.

That is a basic circuit to give you independant control
of direction and whether the motor runs or not. It was not
clear what you have in mind as to timing and changing
direction. However, whatever you want to do is achievable
by controlling how/when/how long you energize the relays.

Ed


.

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