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
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.
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.
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.
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.
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.
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
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.