Relays as switching devices
Table of Contents
ToggleProblem: The signal output of a small reed is too weak to switch a DC-motor. Solution: Using a relay!
![Relay as a swiching step](https://sp-ao.shortpixel.ai/client/to_auto,q_glossy,ret_img,w_669,h_184/https://learnchannel-tv.com/wp-content/uploads/2017/04/relay.gif)
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, Relay - how it works](https://sp-ao.shortpixel.ai/client/to_auto,q_glossy,ret_img,w_681,h_288/https://learnchannel-tv.com/wp-content/uploads/2019/06/Relay-function.gif)
Relay - function
Advantages of a relay compared with electronic switches:
- Galvanic isolation (if you don´t use an opto-coupler)
- Higher switching capacity
Disadvantages:
Relay for memory functions within the control circuit
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Problem: The memory function of the valve is lost with the spring reset.
Solution: The memory function must now be carried on the control side, i.e. the electrical circuit. The solution is a so-called latching relay:
![Latching relay circuit - how it works](https://sp-ao.shortpixel.ai/client/to_auto,q_glossy,ret_img,w_699,h_431/https://learnchannel-tv.com/wp-content/uploads/2022/11/Latching-relay-circuit-how-it-works.png)
Latching relay circuit - how it works