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What do you mean by open-collector output?
An Open Collector output is an NPN transistor. An NPN transistor allows the sinking of current to common. It can be thought of as a switch that allows the circuit, after the load, to be connected to common. This means that a source is required for the output to work.
Is open-collector sinking or sourcing?
While the NPN open collector transistor circuit produces a “current-sinking” output, that is the NPN transistors open collector terminal will sink the current to ground (0V), a PNP-type transistor can also be used in an open collector configuration to produce what is called a “current-sourcing” output.
What is the output of a relay?
A relays Output Circuit is the portion of the relay that switches on the load and performs the same function as the mechanical contacts of electromechanical relays. Solid-state relays, however, normally have only one output contact.
Is NPN an open collector?
Open-collector (also called open-drain, NPN, or PNP) is a very common type of digital signal. Rather than providing a low-impedance 5 volts and ground, like a push-pull or signal, an open-collector signal provides open and ground. This type of signal can be thought of as a switch connected to ground.
What is the difference between open collector and tri state output?
A three-state logic device is unlike an open collector device, because it consists of transistors to source and sink current in both logic states, as well as a control to turn off both transistors and isolate the output.
What is open-collector mode?
An open collector is a common type of output found on many integrated circuits (IC), which behaves like a switch that is either connected to ground or disconnected. The emitter of the transistor is connected internally to the ground pin.
What is output of PLC?
PLC outputs are of two general types: (1) relay. (2) solid state. Relay outputs are mechanical contacts and solid state outputs may take the form of transistor or TTL logic (DC) and triac (AC). Relay outputs are usually used to control up to 2 amps or when a very low resistance is required.
Is a relay an input or output?
A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof.
How does the open collector work on a relay?
To do this, connect an open collector digital output to the control terminal of the relay board, with a 10kΩ resistor pulling the line up to +5V. This way, the relay will be constantly powered until the open collector digital output is switched on, which will then cause the control line to become grounded.
How to switch circuit with open collector digital output?
Switching a circuit with an open collector digital output. Connect your circuit in series with the digital output, as pictured. The load could be a larger relay, a solenoid, LEDs, light bulbs, motors, etc. Check the specification table on the product page for your Phidget to ensure that the voltage required by your load does not exceed the maximum.
Can a DC relay pick up an over current?
If the relay is connected collector to the positive DC, and the impedance won’t allow an over current into the open collector on a zero output (not zero current), then the relay should try to pickup. The pull up resistor won’t matter to the relay. However, a freewheeling diode maybe required across the relay to prevent back emf.
Is there such thing as an open collector?
Those familiar with integrating relays with an automation or security system are sometimes baffled when, instead of seeing the Common, Normally Open and Normally Closed terminology associated with a relay, they read in the instructions that the device has an open collector, or solid-state, output. So what is an open collector? How do you use it?