Introduction to Switches – Zero Ohm Electronics

Introduction to Switches

Posted by Momen Odeh on

What are SPDT, DPDT, NC, NO etc for switches?

In this tutorial, we are going to learn about the different types of switches and contacts that you could see for normal "ON-OFF" switches or for relays contacts.

SPST: Single Pole Single Throw

The most basic type of switch, a picture is worth a 1000 words
It is just an ON or OFF switch

SPDT: Single Pole Double Throw

switch-spdtSPDT as you can see, contains one additional line compared to SPST
The additional line creates the concept of Normally Open "NO" and Normally Close "NC"
Basically the "pole" is normally connected to the "NC" point, when you press/activate the switch,
the "pole" changes position and connects to "NO" point

DPDT: Double Pole Double Throw

These are sisters to SPDTs, they just have an additional set of connections, mostly this additional set is:
Electrically Isolated from the first set.
Mechanically connected to the first set
This means that a single press activates two electrically isolated switches
The red concave which you can buy from Zero Ohm online store is related to this tutorial. Yes! this is a button like the one you use with Arcade games, it uses a micro-switch which gives the user a COM, NO, and NC contacts
This Small Switch is a PCB mount ON/OFF or selection switch, you see it everywhere, and now we have it, it has a COM, NC and NO contacts
Last but not least, the Relay, this awesome component can be used to switch High Voltage (HV) loads using a small 5v signal, it is an SPDT relay and has a COM, NC and NO contacts
If you face problems or if you have questions, feel free to leave a comment below.

Share this post

← Older Post Newer Post →

Leave a comment

Please note, comments must be approved before they are published.

Liquid error: Could not find asset snippets/bold-currency-converter.liquid