current detection circuit

[vikky]

Can anyone give me a circuit for detecting current.i want to take the O/P to a relay
to indicate whether there is current flowing or not.i am using a current transducer for this purpose.Thanku

 

[ravimarcus]

current detector circuit

Can anyone give me a circuit for detecting current.i want to take the O/P to a relay to indicate whether there is current flowing or not.i am using a current transducer for this purpose.

Is the current AC or DC? What is the voltage level? What is the specifications of the current transducer that you have?

Cheers

Ravi

 

[dinesh agarwal]

current detection

what amount of the current is flowing

 

[vikky]

current detect circuit

thanks 4 ur reply.the current is DC.voltage level is 40mV to 4VCurrent is 1 to 100A.
specification of the transducer is

Vc Supply Voltage +/-15V
Ic Current consumption +/-15A
Load resistance >1Kohm

 

[ravimarcus]

thanks 4 ur reply.the current is DC.voltage level is 40mV to 4VCurrent is 1 to 100A. specification of the transducer is

Vc Supply Voltage +/-15V
Ic Current consumption +/-15A
Load resistance >1Kohm

If your transducer gives you 40 mV to 4V, then you can interface it directly to the uC's ADC. There is no need of any circuit.

If you want to just detect current flow and operate a relay, then feed the transducer output to a comparator. When the voltage goes above 40 mV, you will be able to operate a relay.

Cheers

Ravi

 

[vikky]

ac current detection circuit

Thanku for your reply.but in the second case it will be only current coming.so we have to detect current and operate the relay.can v use a I to V convertor or is there a better method.

 

[ravimarcus]

high current detector circuit

Put a shunt resistor across the o/p and ground. The I will get converted to V. Then you can do what you want

Cheers

Ravi

 

[kender]

low current detection circuit

Do you want:
high-side current sensing - current sensor between supply and load (your IC),
or low-side current sensing - current sensor between the load and ground
?

If you need to decide betwen high- and low-, look at this app note: **broken link removed**.

Tell us a little bit more about your load and the device you're building.

 

[vikky]

current-detection

@kender

i went through your link.it was useful.i would prefer high side current sensing.
i am taking the O/P from the sensor and it detects the current.it is a current transducer.The current is coming out as a O/P from a electrolyitc solution.The input given is voltage.

Thanks ravi 4 ur suggestion.

then...i went through max4375 chip.i found it useful.there is a window detection
circuit.i think it will help me in my purpose.i have given the link below.
**broken link removed**.
this i think i can use for detecting current and 4 detecting voltage
i can give the o/p to adc of uC thanks to ravi's idea.

kender and ravi...any suggestions???

 

[vikky]

current flow detection ic

My transducer does not give 40mV to 4V.now wat is the solution for this problem?

Added after 3 hours 52 minutes:

Can microcontroller sense 40mV.Is the resolution of microcontroller upto that?

 

[kender]

low current ac detection

Can microcontroller sense 40mV. Is the resolution of microcontroller upto that?

If you have a 10-bit A/D, and a 5V reference voltage (Vref), 40mV will correspond to 8 counts. The effective resolution of your A/D will be 3 bits. OK, you can lower the Vref to 1.25V. Then you'll get an effective resolution of 5 bits. Would that be a sufficient resolution for your application?

If not, you should add an amplifier. Probably, a non-inverting OpAmp.

By the way, here's a broader app note on current sensing. It covers both resistive and hall-effect sensors: **broken link removed**
If you decide to go with a Hall-effect current sensor, you should check out **broken link removed** and Allegro

 

[kender]

current sensor using detection circuit method

By the way, here's a broader app note on current sensing. It covers both resistive and hall-effect sensors: **broken link removed**

That app note was moved here:
Here's a another interesting one about magnetoresistive sensors:**broken link removed**. E.g. ZMC05 and ZMC20 current sensors.