brainb
Newbie level 3
- Joined
- Sep 10, 2009
- Messages
- 3
- Helped
- 0
- Reputation
- 0
- Reaction score
- 0
- Trophy points
- 1,281
- Location
- South Africa
- Activity points
- 1,303
diagram of transient voltage supressors
I have a question in terms of protecting a microprocessor output that drives a relay from back emf.
I have attached a diagram of the circuit, which I have come across.
I understand why the TVS (transient voltage suppressor) is used, but why is the resistor connected in parallel over the coil.
Is it acting as a filter or is the resistor absorbing the back emf spike?
Is the resistor not just providing another path for the back emf to damage the output card? What are the risks involved with connecting the resistor in this configuration?
Hopefully this makes sense?
The output card does have enough current to pick the coil.
Any comments / suggestions would be appreciated.
Thanks,
I have a question in terms of protecting a microprocessor output that drives a relay from back emf.
I have attached a diagram of the circuit, which I have come across.
I understand why the TVS (transient voltage suppressor) is used, but why is the resistor connected in parallel over the coil.
Is it acting as a filter or is the resistor absorbing the back emf spike?
Is the resistor not just providing another path for the back emf to damage the output card? What are the risks involved with connecting the resistor in this configuration?
Hopefully this makes sense?
The output card does have enough current to pick the coil.
Any comments / suggestions would be appreciated.
Thanks,