Hello,
I have a power supply of 12v 2A and i am using it to drive a motor. i want to make a circuit such that when the current through motor will be more than 1A LED should glow. please help.

 

Most of us draw the line at working for free. Show us your ideas.

 

There are several ways to do this, with different degrees of accuracy and complexity. Look up "current shunt" to learn about the sensing element. Also, you can search for a current monitor schematic to see several examples.

ak

 

hi,
i am trying to make a vehicle like a car and using dc motors for it.

 

i am trying to make a vehicle like a car and using dc motors for it.

Fine. Show us a schematic with your ideas for current sensing.

 

Fine. Show us a schematic with your ideas for current sensing.

I do not have any idea about how to mesaure a current,i have used ammeter but that is not possible to use in circuit obviously.

 

Search for current sensing with op amp,,,, or current sense transformer circuits,

These are two methods to sense current levels.

 

I do not have any idea about how to mesaure a current

Have you tried using Google or some other search engine? That will bring up schematics and devices that will do it.

 

I do not have any idea about how to mesaure a current,i have used ammeter but that is not possible to use in circuit obviously.

OK, so you want to measure current and throw or trip a flag when the current exceeds a level, in this case 1 amp. There are a few ways to go about it as was mentioned. Obviously you will need some method to sense current. A simple Google of "current sensors" will get plenty of results. I would use something like this. Using a pre packaged device makes things easier. This will give you a voltage out which is proportional to the sensed current. The voltage can be used with a voltage comparator circuit so when 1.0 amp is exceeded a LED illuminates. You want the comparator to include hysteresis which is explained in the link.

What you want to do is not difficult but does require a basic working knowledge of some electronic theory. You can also look for what I call a turn key solution which is what you want all in one package for a price. Google is your best friend for those solutions.

Ron

 

If you can afford to lose about 0.6V of your 12V then the simplest solution would be to pass the motor current through a 0.6Ω 3W resistor and use the voltage developed across the resistor to turn on a transistor when >1A motor current is drawn. The transistor would drive the LED.

 

If you can afford to lose about 0.6V of your 12V then the simplest solution would be to pass the motor current through a 0.6Ω 3W resistor and use the voltage developed across the resistor to turn on a transistor when >1A motor current is drawn. The transistor would drive the LED.

Inexpensive and simple, I like that approach.

Ron

 

If you can afford to lose about 0.6V of your 12V then the simplest solution would be to pass the motor current through a 0.6Ω 3W resistor and use the voltage developed across the resistor to turn on a transistor when >1A motor current is drawn. The transistor would drive the LED.

thank you very much for this help,
will you please elaborate why specifically that 0.6ohm and 3W resistor? because i cant understand it.i tried to use ohm's law but still can't figure it out.

 

Hello,
I have a power supply of 12v 2A and i am using it to drive a motor. i want to make a circuit such that when the current through motor will be more than 1A LED should glow. please help.

Something like this?

 

View attachment 121672


Something like this?

No. I am using L239d motor driver IC

 

If you're using a L239d, then you will need a sensor to detect the reverse direction current, so you can use a current transformer, or an opamp and series drop resistor like this circuit...






You will need two op amps across one sense resistor, OR one opamp in series with the chip supply.

 

If you're using a L239d, then you will need a sensor to detect the reverse direction current, so you can use a current transformer, or an opamp and series drop resistor like this circuit...



View attachment 121682


You will need two op amps across one sense resistor, OR one opamp in series with the chip supply.

thanks

 

See

 

See
View attachment 121689

thank you very much for the help sir.

 

i cant understand the graph
the voltage curve looks fine but the current is confusing me.
is it current to voltage converter???
please help.

 

Inexpensive and simple, I like that approach.

For some reason, this did not post yesterday:
As long as you protect the transistor so it isn't carrying all of the output current above 1 A through the base-emitter junction diode.

ak