Showing posts with label directional. Show all posts
Showing posts with label directional. Show all posts
Friday, September 12, 2014
Bi directional motor
This is a simple and easy to construct schema that can be used to provide a bidirectional drive to a DC motor. The schema operation is straight forward. Output of an astable mutivibrator based on IC1 (NE555) is used to control the relay RL1 driving the motor. The motor is connected between the two poles of the relay contacts. The relay contacts are so wired as to reverse the DC supply to the motor when the contacts changeover.
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The astable multivibrator produces a square wave at the output with its high time given by 0.69(R1+R3+R5)C1 and low time given by 0.69(R1+R2+R4)C1.The high and low times can be varied by varying potentiometers R4 and R5.For the given values the high and low times can be adjusted between 1S and 8S separately. When the IC1 output is low, the relay is de energised and the relay contacts are in position 1-1 with the result that A terminal of the motor is positive and motor runs in one direction. The IC1 output is high the relay is energised and the contacts changeover to position 2-2.Now the terminal B of the motor becomes positive and motor runs in the opposite direction. The transistor Q1 is used to drive the relay according to the output from IC1.The diode D4 acts as freewheeling diode.
Notes.
* Assemble the schema on a good quality PCB.
* The schema can be powered from a 12V DC power supply.
* The IC1 must be mounted on a holder.
* The capacitor C1 must be rated at least 15V.
* The relay RL1 can be a 12V DPDT relay.
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The astable multivibrator produces a square wave at the output with its high time given by 0.69(R1+R3+R5)C1 and low time given by 0.69(R1+R2+R4)C1.The high and low times can be varied by varying potentiometers R4 and R5.For the given values the high and low times can be adjusted between 1S and 8S separately. When the IC1 output is low, the relay is de energised and the relay contacts are in position 1-1 with the result that A terminal of the motor is positive and motor runs in one direction. The IC1 output is high the relay is energised and the contacts changeover to position 2-2.Now the terminal B of the motor becomes positive and motor runs in the opposite direction. The transistor Q1 is used to drive the relay according to the output from IC1.The diode D4 acts as freewheeling diode.
Notes.
* Assemble the schema on a good quality PCB.
* The schema can be powered from a 12V DC power supply.
* The IC1 must be mounted on a holder.
* The capacitor C1 must be rated at least 15V.
* The relay RL1 can be a 12V DPDT relay.
Thursday, August 14, 2014
Build 16 Stage Bi Directional LED Sequencer
The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock signal for the counter and the rate can be adjusted with the 500K pot. Two additional Schmitt Trigger inverters are used as a SET/RESET latch to control the counting direction (up or down). Be sure to use the 74HC14 and not the 74HCT14, the 74HCT14 may not work due to the low TTL input trigger level. When the highest count is reached (1111) the low output at pin 7 sets the latch so that the UP/DOWN input to the counter goes low and causes the counter to begin decrementing.
When the lowest count is reached (0000) the latch is reset (high) so that the counter will begin incrementing on the next rising clock edge. The three lowest counter bits (Q0, Q1, Q2) are connected to both decoders in parallel and the highest bit Q3 is used to select the appropriate decoder. The schema can be used to drive 12 volt/25 watt lamps with the addition of two transistors per lamp as shown below in the section below titled "Interfacing 5 volt CMOS to 12 volt loads"
Circuit diagram
schema from Link
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