Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

can anyone give me idea of relay coil discharge during off conditions..

Status
Not open for further replies.
D

deepakchikane

Full Member level 3
Full Member level 3
Joined
Jul 17, 2012
Messages
178
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,298
Location
Mumbai, Maharashtra, India, India
Activity points
2,623
can anyone give me idea of relay coil discharge during off conditions..

the voltage takes time to discharge thru freewheel diode...


is there any ways so i can reduce the discharge time relay so can get better effect at the output...
 

If you are using fast response diode like zener diode and schottky diode, the discharge will take place fatsly.. so that, you reduce the time taken to discharge.
 

    V

    Points: 2
    Helpful Answer Positive Rating
A relay coil generates a magnetic field, often concentrated in its core or magnetic circuit. When the current is interrupted, the field returns a reverse voltage on coil terminals.
You can "swallow" this voltage (often quite high) by connecting a diode across the coil, so the current can pass but the voltage gets "shorted" by the diode.
To fasten the process, the diode can be "fast" like a Schottky, and the coil inductance as small as possible. You can also replace the diode with a power MOSFET wih a low channel resistance, and use a control gate pulse to discharge the coil after the current ends.
 

jiripolivka said:
A relay coil generates a magnetic field, often concentrated in its core or magnetic circuit. When the current is interrupted, the field returns a reverse voltage on coil terminals.
You can "swallow" this voltage (often quite high) by connecting a diode across the coil, so the current can pass but the voltage gets "shorted" by the diode.
To fasten the process, the diode can be "fast" like a Schottky, and the coil inductance as small as possible. You can also replace the diode with a power MOSFET wih a low channel resistance, and use a control gate pulse to discharge the coil after the current ends.
Click to expand...

jiripolivka..
thanks for the suggestions,
but during both conditions the gate will gate charge from coil upper end (coil second end will b gnd)
& i thing relay will not get the voltage
 

I do not understand what you mean by "gate charge". MOSFET channel is used to discharge the coil (it has a smaller resistance than a diode and no forward resistnce like a diode), and the gate is used to control the MOSFET.
 

jiripolivka said:
I do not understand what you mean by "gate charge". MOSFET channel is used to discharge the coil (it has a smaller resistance than a diode and no forward resistnce like a diode), and the gate is used to control the MOSFET.
Click to expand...

where i should have to connect gate pin..??

- - - Updated - - -

pfa handmade schematic...
 

Attachments

  • DSC_0129.jpg
    DSC_0129.jpg
    773.9 KB · Views: 217

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top