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Q: What role does a resistor have that is installed in parallel to a relay coil?
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Why wouldn't the shunt resistor in the ammeter protect the ammeter when the ammeter is connected in parallel?

Connecting an ammeter in parallel subjects that ammeter to the full supply voltage. The shunt resistor is not designed to sustain that value of voltage and will burn out. Also, the clue is in the word 'shunt' (which means 'in parallel') which means that the coil will also burn out!


How do you interface a relay to a microprocessor type 89C51?

you cannot directly interface a relay to a microcontroller, you need a buffer circuit in between the two, you can use a NPN transistor BC 547, connect the controller pin directly to the base of the transistor (since there is an internal 10k pull up resistor inside the controller no need of any base resistor). Connect the transistors emitter to the gnd & the collector to the relay coil, the another end of the relay coil goes to the supply, check this link for complete information http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Relay-Interfacing.html


What ll be effect if resistor in snubbing circuit is opened?

The resistor in the snubbing circuit is there to minimize the reverse EMF spike that occurs when a DC inductive load, such as a relay coil or other electromagnet is released. Opening the snubbing circuit will expose the driving circuit to high voltage transients that can damage it.


What is percentage bias relay?

This is basically a differential relay that contains an additional restraining coil with the operating coil connected at its midpoint used to prevent the unnecessary pick up of the relay.


What is transistor relay driver?

a transistor circuit for driving the coil of a magnetic relay.

Related questions

What is the difference between led and relay interface?

LED interface requires typical 220 Ohm resistor in series While in case of relay resistor comes across coil with its value depends on supply voltage


What is the purpose of a seal-in contact?

This is a small electromagnet whose coil is in series with the relay contacts and whose contact is in parallel with them. The electromagnet is energized, closing its contacts in parallel with the relay contact as soon as the trip coil is energized, and drops out when the circuit breaker opens.


Why reduce voltage from a ignition coil by putting a resistor in the spark plug?

Sometimes a resistor is installed in spark plug wire as a supressor to reduce radio static interference


How is a shunt coil installed?

'Shunt' is an archaic term, meaning 'in parallel with'. So a 'shunt coil' is connected 'in parallel' with... With what, of course, depends upon what sort of device you are talking about. For example the field coil of a d.c. shunt-connected motor has its field winding connected in parallel ('shunt') with the supply.


When using an arduino controlling a relay- why are resistors used with the transistor to activate the relay coil?

Because without the resistor, there would be a short from the base to ground, and sometihng would smoke.


Why wouldn't the shunt resistor in the ammeter protect the ammeter when the ammeter is connected in parallel?

Connecting an ammeter in parallel subjects that ammeter to the full supply voltage. The shunt resistor is not designed to sustain that value of voltage and will burn out. Also, the clue is in the word 'shunt' (which means 'in parallel') which means that the coil will also burn out!


What size resistor is needed to allow a 220 volt coil in a relay operate on 277 volts?

You will need to know the amount of current flowing through the coil when 220 volts is applied across it. A resistor in series with the coil will limit the current so that the coil only sees 220 volts. The resistor will need to drop 57 volts. So, 57 volts divided by the current in amps will give you your required resistance. You will need a resistor with a high power dissipation rating with 57 volts across it. Your resistor will probaly need to dissipate several watts. For example: A 220 volt coil with 300 milliamps (.3 amps) will require a resistor of 733 ohms. The power dissipation of the resistor would need to be 17.1 Watts! You might try using a light bulb as a series resistor. Ensure that it can handle 57 volts. To complicate matters, is that AC or DC you are using? AC relays have inductance build in, in order to increase the specific "ac resistance", thus the same coil could use as little as 0,001A so you will need a very low value resistor. Anyway, if any 220V relay uses as much as 300mA, I doubt if you will be able to pick it up with one hand! Such a relay coil will draw about 66W of power! I have a 16A rated contact 230V relay. Its current is 0,0015A that is equivelant to 0.33W at 220V!


How do you interface a relay to a microprocessor type 89C51?

you cannot directly interface a relay to a microcontroller, you need a buffer circuit in between the two, you can use a NPN transistor BC 547, connect the controller pin directly to the base of the transistor (since there is an internal 10k pull up resistor inside the controller no need of any base resistor). Connect the transistors emitter to the gnd & the collector to the relay coil, the another end of the relay coil goes to the supply, check this link for complete information http://www.dnatechindia.com/index.php/Tutorials/8051-Tutorial/Relay-Interfacing.html


Where is coil relay on 1986 ford eco van?

There is no such thing as a coil relay.


Where is the resistor for the coil on a mercruiser 470?

The Cable is the Resistor ! Its a Resistor-Cable ! Greets from the Lake of Constance/Germany !


What is a relay coil?

Most relays have an internal electromagnetic coil that is energized when the relay is activated.


Where is the heater resistor coil located on a 2006 t300 kenworth?

The heater resistor coil is located on the blower motor on the 2006 T300 Kenworth.