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Comment by Buttons840 | Hacker News Reader

How? Use batteries only?

Obviously I shouldn't plug my own creations directly into the wall. Is it safe to use a low voltage "power brick"? Will any do, or do I need an especially robust one just in case?

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Power bricks should be fine. I'd suggest starting out with a pretty low voltage (5, maybe up to 9), in DC.

Keep in mind though, that while these voltages are generally below the threshold required to conduct through skin, and represent little shock hazard, pretty much any electrical system can be hazardous in other ways.

In particular, you can create a fire hazard even with pretty low voltages, if the resistance is low enough and your power supply is capable of providing enough current. Likewise for sparks: if, FSM forbid, you happen to have some explosive vapors around (and even a bottle of fingernail polish remover can be a source of explosive vapors), a small spark can start a fire.

My point isn't to try to scare you off, but rather to say that you always need to be cautious, pay attention to what you're doing, and keep safety in mind, even when playing with low voltages.

The nice thing about batteries is that you can add them up to whatever voltage you need. Common electronics voltages are 5V, 9V, 12V, 18V, 24V. You can achieve all of these with different numbers of rechargeable AA or 9V batteries.

However, because of the variety of projects you'll do, to use a wall power source you'll need either a variety of adapters of different voltages, or one of those expensive multi-voltage power adapters, or a proper bench power supply.

So, yes, one of those 5V or 9V wall adapters is perfectly fine to use. You simply buy the female portion of the adapter and connect it to your circuit. However, if you do end up exploring multiple projects early on, using batteries will reduce the amount of new expensive gear you need to buy.

As a kid I played with batteries and wall bricks or wall warts or whatever you call them(transformers). I would not say you need an especially robust one. They come in different sizes based on the amount of voltage they output and the potential current they can supply. Basically if you are playing with a 9 volt battery and want to replace it with a transformer just look for one that says 9v DC output on it.

There are people who say things like its not the voltage that kills its the current but through the human body under normal conditions it takes a decent bit of voltage to induce enough current to really hurt you. Watch out for things with large capacitors and large voltages. If you want to take something like that a part let it sit for a long time for the capacitors to discharge. I worked at a TV repair shop in high school dismantling tube TVs for scrap components. The first step after opening was to use a large screwdriver to discharge the flyback transformer.

> Watch out for things with large capacitors and large voltages.

Oh man I have some retrocomputing equipment I really want to play with but I'm a little worried as there's a huge capacitor, some of the wires coming off the power supply manual are visibly old and to add to it, one of the first pages in the maintenance manual is a CPR guide.

I would not say you need an especially robust one. They come in different sizes based on the amount of voltage they output and the potential current they can supply.

They're also typically really cheap, which can be an advantage if you fry one. Or two. Or ten. Not that I'm speaking from experience or anything. :-)

Seriously though, if you have any kind of thrift store, surplus store, or something of that nature near you, you can often pick up random wall warts for next to nothing.

I recommend playing with 5V, many Arduinos and microcontrollers run on that, or have a voltage converter that allows them to accept it. And this means you can use a stripped USB cable from a standard usb wall plug to power your projects.

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