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Relays as switching devices
Problem: The signal output of a small reed is too weak to switch a DC-motor. Solution: Using a relay!
Relay as a swiching step
Functioning of a relay:
Relays are electromechanical devices consisting of an electromagnet und some contacts. The switching mechanism is carried out when the electromagnet is under voltage – that means the relay is “activated”.
Relay are mainly used when a low-power signal has to control a circuit with high power.
Relay - function
Advantages of a relay compared with electronic switches:
- Galvanic isolation (if you don´t use an opto-coupler)
- Higher switching capacity
Disadvantages:
- Low switching frequency
- Mechanical switching means wearing
