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DIY your own 5V relay module, using 2N2222 and Songle/LongLing coil

If you are a DIYer or maker, and you want to build everything yourself, then you may consider using 2N2222 and Songle/LongLing coils.

Or you would like the members of your robot club learn how to control motors using relays, then you might like to buy perhaps 100 kits. 2N2222 in 100 quantities is only HK$0.1 each, and Songle relay is HK$1 each.

DIY your own relay module is also

a way to solve your No Audio Click problem

. Say if suspect you coil is not working, you can troubleshoot by removing the coil and try to measure its resistance (70R), or drive it using 2N2222. You may also want to replace your broken relay coil one day when it has opened and closeed millions of times.

If you are a software guy and know little electronics, you need to know the very basic relay operation. Below are two good references.

How does an Electric Relay work? - techydiy.org

Build Your Own 5V Relay Module [2N2222, Songle relay, rpi] - Nick' Blog

DIY your own module using 2N2222

If you are a DIYer or maker, and you want to build everything yourself, then you can use a Songle or

How does an Electric Relay work?

Built Your Own 5V Relay Module [using 2N2222, driven by rpi] - Nick Momrik 2017jul05

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DIY your own 5V relay module, using 2N2222 and Songle/LongLing coil

If you are a DIYer or maker, and you want to build everything yourself, then you may consider using 2N2222 and Songle/LongLing coils.

Or you would like the members of your robot club learn how to control motors using relays, then you might like to buy perhaps 100 kits. 2N2222 in 100 quantities is only HK$0.1 each, and Songle relay is HK$1 each.

DIY your own relay module is also

a way to solve your No Audio Click problem

. Say if suspect you coil is not working, you can troubleshoot by removing the coil and try to measure its resistance (70R), or drive it using 2N2222. You may also want to replace your broken relay coil one day when it has opened and closeed millions of times.

If you are a software guy and know little electronics, you need to know the very basic relay operation. Below are two good references.

How does an Electric Relay work? - techydiy.org

http://www.techydiy.org/how-does-an-electric-relay-work/

Build Your Own 5V Relay Module [2N2222, Songle relay, rpi] - Nick' Blog

https://nick.blog/2017/06/22/5v-relay-module/

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Up shifter using 2N2222

And if you want to entertain only one relay module, then the 4 shifters in 1 chip HCT125/HC04 is a waste or overkill. Then you may consider single transistors (such as BJT NPN 2N2222, MosFet 2N7000). I tried 2N2222 the other day and found it OK.

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