arduino Uno R3 power my project (wall wart and transistors)

The more I read the more I know that I now nothing about this stuff…

the project, I want to make a smart power-strip (timer, IR remote, LCD, photo-resistor) to control lights or other devices put into the power-strip.)

I’m now building the electronics on a breadboard, to make sure it, and the code all work.

The problem: need moar powaa (using USB from PC now, which is causing issues)

what I want to do:

Connect a 9V 1A adapter to the Arduino, then connect a DC-DC converter to the Vin from the Arduino to convert from 9v to 5v. Then put the 5V output from the DC-DC convertor on the breadboard powerrail. And connect the negative to the arduino gnd to create a common ground reference. Is it better to connect the DC-DC converter directly to the 9V adapter? I don’t like to splice/cut the cable if I don’t have to. and I will not draw anywhere close to the 1A which is the maximum of the protection diode on the Vin of the arduino.

Then I still need some transistors. This is where I really have no clue what to get. there seem to be thousands or millions of them and they all have very similar specs. What is a good one for general Arduino use. I have a few TIP122 Darlington transistors, but there are so many others (2N3904, 2N3906, SS8550D, BC585,) I think the PN2222 is a good one to have around?

Is there any sense to be made of all these transistor part numbers? I’m looking for a switching transistor as opposed to an amplifying one.

My eyes gloss over reading stuff like this. Just draw (and attach) a drawing/schematic what you are proposing.

'm looking for a switching transistor as opposed to an amplifying one.

They can all be used for switching and amplifying there is no difference.

freegame: Connect a 9V 1A adapter to the Arduino, then connect a DC-DC converter to the Vin from the Arduino to convert from 9v to 5v. Then put the 5V output from the DC-DC convertor on the breadboard powerrail. And connect the negative to the arduino gnd to create a common ground reference. Is it better to connect the DC-DC converter directly to the 9V adapter? I don't like to splice/cut the cable if I don't have to. and I will not draw anywhere close to the 1A which is the maximum of the protection diode on the Vin of the arduino.

Use a 5volt/500mA cellphone charger, and plug it's USB lead into the USB socket. You can use the supply's current minus what the Arduino uses from Arduino's 5volt pin. There might be a polyfuse on the Uno that trips over ?500mA. Leo..

freegame: Then I still need some transistors. This is where I really have no clue what to get. there seem to be thousands or millions of them and they all have very similar specs. What is a good one for general Arduino use. I have a few TIP122 Darlington transistors, but there are so many others (2N3904, 2N3906, SS8550D, BC585,) I think the PN2222 is a good one to have around?

Is there any sense to be made of all these transistor part numbers? I'm looking for a switching transistor as opposed to an amplifying one.

I found that MMBT9014 (NPN) and MMBT9015 (PNP) were actually more commonly in stock with suppliers in China, than the "traditional" general purpose parts. They must have found a niche in new designs where a 2N3904 or 2N3906 (or for that matter a 2N2222A) would be previously be used for general purpose applications. So they are my new go-to part, so I stock hundreds of them. I believe they are slightly cheaper.

But in the majority of circuits, any of them could be used. Of course you have to make sure by checking the specs. As their use in consumer electronics dwindles, you see fewer and fewer types on the actual shelf.

Why don't you put the 9 v. into a 7805 fixed 5 v. regulator, and then take the 5 v. output to the power rail on the breadboard. Then power the arduino and all other components from that.

In my experience, if you start with a higher voltage, like your 9 v., it is a good idea to downconvert it to 5 v., but limit the 9 v. to the input to the 7805. Putting it on the breadboard power rail invites the likelihood of accidentally feeding it to some hapless 5 v. part, which will promptly give up its smoke. I speak from experience.

Thanks,

these are some useful ideas.

Wawa: Use a 5volt/500mA cellphone charger, and plug it's USB lead into the USB socket.

I might do something like this when I put everything inside the power-strip. But I like to keep the USB open to allow for updates. Also I'm now testing the code and need to connect to a PC to read serial and upload code.

I could put the USB charger output on the Arduino power connector, however the specs recommend a minimum of v when powering the device this way. So I'm not sure if that is a good idea. I could put it directly on the Vin pin, but then I would need a very nice and stable source, which I'm not sure I will have with my unskilled wiring and tinkering.

aarg: I found that MMBT9014 (NPN) and MMBT9015 (PNP) were actually more commonly in stock with suppliers in China,

I'm actually living in China so this is good to know. The shops where I normally order don't have the XN2222X.

jrdoner: Why don't you put the 9 v. into a 7805 fixed 5 v. regulator, and then take the 5 v. output to the power rail on the breadboard. Then power the arduino and all other components from that.

I have a couple of 7805's here, but I also have some LM2596S based DC-DC modules. I was planning on using one of those.

I though the arduino liked to get a minimum of 7V on the arduino power connector. If 5V is enough I could just use a 5V phone charger like Wawa is suggesting, eliminating the DC-DC convertor.

Anyway, whi all this I can try out some things and see what will work out best for me.

5V is enough if you connect it to the 5V pin. It is 7V or above for the Vin pin or the power jack.

I found a nice set of 20 types 200 total transistors for $2.1 incl shipping (on taobao).

编号 型号 极性 数量 单位 S9012 PNP 10 PCS S9013 NPN 10 PCS S9014 NPN 10 PCS S9015 PNP 10 PCS S9018 NPN 10 PCS S8050 NPN 10 PCS S8550 PNP 10 PCS 2N5551 NPN 10 PCS 2N5401 PNP 10 PCS 2N3904 NPN 10 PCS 2N3906 PNP 10 PCS 2N2222 NPN 10 PCS C1815 NPN 10 PCS A1015 PNP 10 PCS C945 NPN 10 PCS A733 PNP 10 PCS SS8050 NPN 10 PCS SS8550 PNP 10 PCS TL431 10 PCS 13001 10 PCS

freegame: The more I read the more I know that I now nothing about this stuff....

the project, I want to make a smart power-strip (timer, IR remote, LCD, photo-resistor) to control lights or other devices put into the power-strip.)

What are you going to plug into the power strip? Mains powered equipment? If so I suggest you get some expert assistance to build the strip, mains voltage kills.