How Control rotating direction of motor using switch?

[Nandika]

Hi Friends,
I have a very simple way to change rotating direction of motor.some say,it want to use a H-Bridge.No..this is diagram.

Control direction of amotor.PNG (36.05 KiB) Viewed 8125 times

good luck

[SemiconductorCat]

because of the sparks going on when you opening and closing the switch, it won'tlast for a long time.
Because this kind of micro S.P.D.T switches are not engineered to handle that kind of sparks.

So the ultimate solution is the Hbridge or power MOSFET( as neo told).

MOSFET are good in handling high current loads. and cheap too. As neo told it's about 50/- LKR in
local market.Using a power MOSFET is more advantagous , because using PWM you could easily
control the speed and torque of the motor, and using a single JK-FF you could handle the direction.

review: https://robot.lk/viewtopic.php?f=19&t=2 ... SFET#p8120

[SevenZero]

As Semi... stated, the perfect solution is the H-BRIDGE. The reason is, you will have to use relays instead of switches if you need to work with digital electronics such as with microcontrollers. With relays there will be two problem.
1. Back EMF - This can be sorted out with a diode placed on the reverse direction of the coil
2. Sparks to damage the switching elements of the relay due to high current taken on start of the motor.

Also consider your switches has 4 combinations. So on the H-BRIDGE also, it is the same number of combinations but arranged in the shape of letter H to do amazing things with motors.

hbridge.gif (997 Bytes) Viewed 8089 times

bjt-schematic.gif (23.92 KiB) Viewed 8043 times

All these can simply be avoided with H-BRIDGE. A set of transistors (or Power FETs) arranged in an order where a microcontroller can use to decide the direction. Not only that with a H_BRIDGE, you can control speed of the motor if you use PWM pins of the uC. Lot of variations with that simple arrangement.

Tip: I used L298 IC (Dual H-BRIDEG) many times and found that it is a fantastic solution to minimise the space requirement on the PCB.

[SemiconductorCat]

I'd like to add these things to the discussion too.

There are other two alternatives.

Reed Switches.

Sounds prefect for a law current application[but 0-15A and 0-10000v] ,and when it comes to read switches there
are no sparks. But the problem is it's mechanical behavior it's not suited for PWM application.Because it have
very less on-off cycles. When your PWM goes on and off 10,000 times on off per a hour, it's mechanical
things will be failed.

The next Alternative is Opto-Couplers.

But here you don't need. Opto-coupler based MOSFET or H-bridges are used when we need a complete
isolation of output load from microcontroller/microprocessor system. Ex- When your driving a motor
for a pump,crane or a actuator.

What are the other possible alternatives? Could somebody add more?

[Nandika]

Hi Friends,
Actually,I posted this for our new guest from FB.however,I searched for H-Bridge explanation in EC.But,i couldn't find.
Now,It was solved.

[SevenZero]

I searched for H-Bridge explanation in EC.But,i couldn't find

ROBOT.LK has many articles related to H-BRIDGE. I did a search using 'bridge' word and found following links.

How to use a H_BRIDGE to control a DC Motor
How to build a mini-sumo robot
How to build a balancing robotic platform - Gyrobot
Two Channel RC Pulse to PWM converter
Connecting DC Motor to Microcontroller Tutorial
Connecting Stepper Motors to Microcontrollers Tutorial