Best bench power supply
What’s the best bench power supply? There’s no such thing I’ll be honest with you right from the start. There are however quite a few decent ones, some average ones and some ones best to avoid.
The reason there is no best bench power supply is because everyone has different needs. Some things that are important for one person don’t mean a thing for another so there isn’t going to be a power supply that’s perfect for everyone. What there is out there is a best bench power supply for you. One that does what you want that doesn’t cost too much.
Power supplies for hobby electronics
If electronics is your hobby you probably realise that a power supply is a very useful piece of kit but you probably don’t want to have to spend loads of money to get one. Lets face it most people are on a budget of some sort. What you spend is obviously going to depend on the individual but it’s going to be a balance of some sorts.
You don’t want to spend a lot of money on something that has loads of features you’re never going to understand let alone use.
On the other hand you don’t want to buy something that’s cheap but then after a short period of time you realise it won’t properly do want you wanted it for in the first place. Hands up anyone who’s bought something because it was cheap only to wish you had bought something a little better and a little more expensive.
Like I say its a balancing act between having something too cheap to do the job and something too expensive and complex for you. You want to be somewhere in the middle with a reasonably priced bench power supply that does everything you need.
Buying the best bench power supply for you
Before you can decide what is the best bench power supply for you you need to look at what your requirements are and have a read to find out as much as you can about the features.
When I was a beginner in hobby electronics I got a power supply only to find out there was a really great feature that I didn’t know about or even understand at the time I bought my first bench power supply.
That feature was to be able to set the current limit. Why would I possible want to limit the current that my power supply could provide. Shortly after blowing an expensive IC I realised what it was all about and my bench power supply didn’t have this function.
Tips on buying the best bench power supply for you.
1. If you are a beginner in electronics, read about the features and what they actually do. This will give you more of an understanding of what you want. If I had understood about current limiting I would have bought a bench power supply that had it!
2. look at what you want from a power supply.
What voltage do you need it to supply. Some go up to 60V just because that’s the case you don’t have to get one that supplies that amount. I can’t honestly think of a time when I’ve needed more than 20 Volts and that was rare. More often I’ve used 12 to 15 volts. Again look at the current requirements. These days modern electronic circuits are using less and less power and current so look at what you really need.
3. Don’t just look at your requirements now but try to think to the future. What will you need in a few years time? I know this is difficult but if you are starting to get interested in a particular field in electronics, what will you need for that?
Size and weight
Although not totally linked, the heaviest power supplies are usually the biggest. This may not seem that much of a consideration if it’s just going to sit on your bench. Its called a bench power supply but even if your not going to move it around much you don’t want something too big that gets in the way.
It may sound crazy as its usually a case of the smaller the better but don’t get something too small.
I once got a DSO pocket oscilloscope and one of the biggest problems I had using it was it was too small and light. In use the lead kept pulling it around and it ended up on the floor a few times. In that case a bit of weight would have helped me use it properly.
What is a bench power supply?
A bench power supply is a device that outputs a DC (direct current) low voltage (usually up to about 30V) electrical supply to power what ever it is you want to power. Usually an electronic circuit if you are an electronic experimenter or hobbyist.
Why do you need a bench power supply?
The reasons you need a bench power supply will depend on the individual. Some people will have different levels of importance for each reason.
If you are involved in electronics and electronic circuits you are going to need something to provide power to an electronic circuit. This is where the bench power supply steps in. It’s there in front of you doing exactly that job.
If you are experimenting with a breadboard circuit you will need a power supply. This could be in the form of batteries but this can be difficult. Sometimes the voltage level a circuit needs could be 12V. It’s not uncommon for circuits to require 12 or even 15 Volts.
This is something that’s not easy to get from batteries. It’s not impossible but a bench power supply will do it at the twist of a knob.
It will also have a read out or meter so you will be able to see and select exactly the voltage you need.
It will also stay constant. Its extremely inconvenient when relying on batteries to have them die at a time when you haven’t got any replacements to hand.
A bench power supply doesn’t have to cost the earth and if your just getting into the hobby of electronics it could save you money instead of using batteries.
When I first got into electronics I only used batteries and if you are starting out they are the safest thing to use but after a little while of reading electronic hobby magazines I discovered that bench power supplies existed and I needed to get one for my hobby. I could see how much use it would be for me and how it would make things a lot easier for me in the long run.
What do you need from a bench power supply?
Another thing to consider is what do you personally need from a power supply. Sometimes its easy to forget when looking at all the features and specifications what you actually want.
Apart from the story above about when I bought my bench power supply and realised I wish I’d bought one with current limiting on it. I also wish I’d bought a dual rail power supply. About half of the circuits I was building used a dual power supply. That is a supply of plus and minus. Lot’s of audio circuits use op amps that require a dual supply. Something like +15 and -15 volts is common.
If you want to build a dual rail power supply suitable for powering circuits read my post Breadboard dual variable power supply.
So my “best bench power supply” didn’t quite live up to my hopes. I wish I’d bought one with current limiting and one that could supply plus and minus at the same time. Hopefully you can see the points I’m trying to make and learn from my mistakes to end up with what is the best bench power supply for you.
What is a bench power supply used for?
A bench power supply is used for powering circuits while you are experimenting with them. Maybe on breadboard or stripboard before you finalise everything.
Types of bench power supply
Years ago bench power supplies used to be all linear. They had large transformers and variable linear voltage regulators at the heart of them. This also meant lots of large capacitors which in turn meant big and heavy bench power supplies.
You may have noticed recently if you scan Amazon pages that there are some power supplies that appear to be too small for the current they supply.
I recently built a hobby CNC machine, read my post if that’s something your interested in. It needed about 5 amps at 12 volts to supply mainly the stepper motors and drivers. I found you could get a power supply with those specifications in a small size about half the size of a computer power supply. It seemed very small and light to be able to supply 5 Amps. That was because it was a switched mode power supply. I won’t go into a full technical explanation here about how they work but they are much more energy efficient.
Switched mode power supplies have been around for quite a while but they tended to produce a noisy supply. By that I mean the voltage. When viewed on an oscilloscope you can see the output isn’t flat. This can cause problems when you power an audio circuit as this “noise” can get into the audio stages. That’s not want you want.
However switched mode power supplies have come quite a way in recent years and have improved in leaps and bounds.
Current limiting
I touched on the subject earlier when I bought my first bench power supply. It didn’t have this feature and wish it had.
Why would you want to limit the current your power supply can output? Surely if you paid for one that can supply 2 amps you want 2 amps available?
This was exactly the question I had. It puzzled me until it was explained to me and then it was as clear as day as to why I wish I had it.
I’ve just built a synthesizer euro rack kit. An envelope generator to be precise. In the build instructions and specifications leaflet I can see it only consumes 25 mA of power. That’s a tiny amount of power compared to the 2 amps my bench power supply can output. If you connect the circuit up to the bench power supply and it uses lots more than 25 mA then there is something serious wrong.
If you limit the current the bench power outputs you can limit the amount of damage excessive current can do to a new circuit.
A current limited power supply can save you blowing an IC that has been put in the wrong way round or fine PCB tracks getting burnt.
This is one of the main reasons for using a bench power supply. The instructions for my synthesizer euro rack kit suggest that you first test your finished kit with a bench power supply rather then plugging it straight into a euro rack power supply for exactly that reason.
Do you need to buy a bench power supply?
This may seem an unusual question for a guide entitled best bench power supply but hang on a moment.
Depending on how experienced you are could you build a bench power supply. When I first wanted a bench power supply I was a total beginner and wouldn’t even consider doing anything that involved mains voltage. This was totally correct as I was too inexperienced and didn’t have the confidence. If you are starting out don’t do anything with mains voltage. If you make a mistake it can kill you!
However if you are more experienced and understand mains voltages and its pitfalls you might want to consider building your own bench power supply. Or course it depends on what you need but you can but bits from Amazon like a switched mode supply or two and converters with current limiting and meters. Ive done this but that’s for another post, but you can build yourself a decent bench power supply for a very reasonable cost.
Which bench power supply should you get?
I’ve divided them up for three different types of people.
1. You are a beginner who has just got into electronics and has realised you need a power supply. You don’t want to spend too much money. The thing has to be straight forward to use with simple controls.
2. You have been an electronics enthusiast for a while and are looking to upgrade what you have. Maybe this is a second power supply. You still have a budget to stick to.
3. You want to get the best you can. Money isn’t really a problem.
Other things you may want to consider that bother me and maybe you but nobody else mentions.
I can’t fully explain why but I like my electronic stuff to have a power lead that unplugs. I don’t like power supplies or oscilloscopes that have the mains lead fixed that you cant unplug. The practical advantages are you can unplug it if you want to move it. You wont have to do that thing where you carry it with two hands and then trip over the mains lead as it gets tangled between your legs. Plus if it gets damaged you just plug a new one in.
I like the connections on the power supply unit to be able to be plugged in with a 4mm plug and a terminal post that unscrews to trap a wire. I also like to be able to turn off the voltage to the test circuit from the power supplies front panel. Its the best way if you want to do it quickly. Don’t believe anyone who tells you they’ve never had to disconnect a power supply quickly!
Final thoughts on the best bench power supply
If you read through my guide on buying the best bench power supply, you may have come to the conclusion that I made a complete hash of getting my first power supply. That’s not completely true as although I bought a power supply that didn’t have current limiting and couldn’t supply dual plus and minus’ I did get lots of use out of it and still do. I’ve got a much better and more expensive power supply now but I still use my original when I my dual is powering one thing and I need a simple supply for another circuit.
My first bench power supply wasn’t ideal for me but was still use full. Hopefully my article will help you realise exactly what you need and what you don’t. You can learn from my mistakes and get the best bench power supply that is perfect for you.