What is an open collector signal?

It is a circuit configuration where the collector of a transistor is left open, functioning similarly to an electrical contact switch. It is available in NPN and PNP types, requiring current direction selection based on the connected device.

What are the advantages of line driver output signals?

Because it outputs balanced (differential) logic signals with opposite polarities, it is highly resistant to transmission noise and operates stably even over relatively long distances.

What is a Semi-Open Collector signal?

It is a versatile signal format combining the advantages of both voltage-free and voltage pulse signals, unaffected by the receiver-side voltage. It is a proprietary technology original to COCORESEARCH.

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Technical Info: Types of Pulse Signals

Voltage-Free Signals (Dry Contact)

Signals that only turn a switch ON/OFF without generating output voltage on their own.
To use them as pulse signals, current is measured by applying voltage to the circuit.
Signal sources include contact switches and open collector transistors shown below.

Contact Signal (Dry Contact)

Signal sources using electrical contacts include reed switches, relays, and mercury switches, as well as FET-based dry signal sources (Right diagram).

Open Collector Signal

Using a transistor with an open collector instead of a mechanical contact provides a similar function to electrical contact switches.
PNP and NPN types differ in current flow direction (Right diagrams).

NPN Open Collector Signal

PNP Open Collector Signal

Solid-State Relay (SSR)

Voltage Pulse Signals

Logic Signals

Logic IC

Capable of sourcing and sinking current. The typical voltage level is 5V.
Totem-Pole Output Circuit	Complementary Output Circuit Example of unbalanced output circuit

Line Driver Output Signal

A balanced signal (also called differential or balanced signal) used to eliminate transmission noise effects by outputting logic signals of opposite polarities.
Requires a balanced input circuit on the receiver side. Operates stably over relatively long distances.

NPN Transistor Voltage Output

Similar to open collector outputs, but includes an output circuit where voltage is applied via a resistor.
Also called a pull-up output because the collector voltage is pulled up to the positive rail with a resistor.

Semi-Open Collector Signal

A highly practical open collector signal that combines the advantages of both voltage-free and voltage pulse signals without interference from the receiving side voltage. Originally developed by COCORESEARCH.

Zero-Crossing Signal

Signals that cross the reference potential of 0V into positive and negative ranges. Includes various AC waveforms such as AC tachogenerators, sine-wave encoders, and self-generating electromagnetic flowmeters.

Circuit diagram of zero-crossing signal output