Need Advice Please. Lab Setup

[Berni]

Its not about getting both 30V and 3A at the same time.

Its about having enough range to cover everything you might come across. Why 30V 3A is so common is a debate in its own right (There is a thread about it somewhere) but it is indeed a pretty good range for general electronics work. It lets you reach 24V with some adjustment headroom around it and that's about the highest voltage you commonly find in electronics (Tho 48V is also common in telco) so that you can often sweep the entire operating voltage range of a device (Test both min and max input voltage). Its also common for LCD backlights to run LED strings from 10 to 30V.

Those 3A is a bit arbitrary but is indeed enough to cover the power consumption of most devices, for example USB devices commonly charge at up to 2A. In general things with a LCD screen and fast CPU will consume somewhere in that range when running. Those 3A is also a good fit for charging batteries since that is 1C charge rate for a 3000mAh battery (This is a common capacity for small bateries)

So in general 30V 3A is a PSU that you will very rarely have you saying "I wish this PSU had more oomph". Occasionally i have certainly had the need for more, such as 100V or 300A. While a bench PSU is not a must have thing, it certainly is a welcome one due to how cheap they are and how often you end up using one.

[rstofer]

Its not about getting both 30V and 3A at the same time.
...
So in general 30V 3A is a PSU that you will very rarely have you saying "I wish this PSU had more oomph". Occasionally i have certainly had the need for more, such as 100V or 300A. While a bench PSU is not a must have thing, it certainly is a welcome one due to how cheap they are and how often you end up using one.

But is it worth $473 right now versus some wall warts (cell charging wall warts are so abundant that the EU is considering banning them for sale with new cellphones) or would the money be better spent on a signal generator?  Don't forget the 3 DMMs (of varying price, I hope).

Yes the DP832 is nice but it was pretty far down my shopping list.  I will almost certainly never get to 30V and not even approach 3A.  If I need a battery charger, they're also cheap.  I bought some flashlights that came with a rechargeable battery and charger for < $10.  I bought several so I have chargers all over the house.

The point isn't to find out which things might use a PS but rather those things that can't be done any other way for a lot less money.

Or buy something like the DP832 and be done with it.  I sure like mine.

[rhb]

Probably one of the most valuable approaches is to not buy T&M kit until you can explain to SWMBO why you can't do without it.

Buy kit when you can explain to someone who doesn't know anything about electronics why what you want to buy is essential.  "Here's what I have to do and how long it takes without it.  Here's how long it takes if I have it. " 

That's a useful constraint.  It maximizes the acquisition of what really matters, knowledge.  The more you know, the less you need.  This forces you how to learn how to do things the way the person who figured it out did it.

Have Fun!
Reg

[Berni]

The first PSU doesn't have to be a Rigol DP832 right away.

At work we bought some of these:
https://uk.farnell.com/tenma/72-2690/bench-power-supply-1-ch-30v-5a/dp/2563982
While it looks like your usual old school twiddly knob analog PSU its actually a fully digital one. Both knobs are encoders that let you set the voltage and current on any digit resolution, it reacts instantly to the setting, the 7 segment readouts update fast and offer 1mA resolution, has manually resetable OCP protection. The thing starts up instantly and keeps last setting just like a analog one. If you want you can also get a model with a RS232 or USB interface for SCPI remote controll. Only downside is the fan control is a bit noisy at low speeds(fan PWM noises and keeps dancing around in speed).

Also not saying a lab PSU is the way to charge batteries. I still use standard purpose built chargers for things like Ni-MH AAs or 18650s, but when i have some non standard pack like a 3 series Ni-Mh or lead acid or a pouch type lithium with wires coming out of it etc.. i just hook it up to a lab PSU because having banana terminals and cables for banana to various clips makes it easy to hook up the battery, and i like to see the voltage and current for these batteries where i am unsure if they are dead or still work.

For the price of 77€ i think it is definitely worth having versus using wallwarts or hacked together PSUs.

The next not so expensive but really useful thing is a hot air station. They can be had for under 50 bucks but makes working with small SMD components so much easier.