What hobbyist projects require more than 18 V? - Page 1
Forum section: electronics / beginners

author: be1212
author_rank: Newbie
timestamp: December 10, 2013, 09:49:15 pm
content: I found a DC power supply I like, but it only goes up to 18 V. That's fine for every application I can think of, but I don't want to buy something I'll regret later. Microcontrollers, robotics motors, and ham radios all seem to take less than even 14 V.What are examples of things (motors, components, etc.) which require 18 - 32 V? I know there are things requiring more than 32 V, but I'm not in the market for a power supply in that range.

author: c4757p
author_rank: Super Contributor
timestamp: December 10, 2013, 09:54:02 pm
content: Lots of old-fashioned analog stuff uses +/-15V, so 30V total, but that's going to require two power supplies unless you use a virtual ground anyway.Uh... vacuum tube amps and radios?

author: Lightages
author_rank: Unknown
timestamp: December 10, 2013, 09:59:55 pm
content: Real RS232 requires ±12V, some audio op amp circuits need ±15V or ±18V, programming some eproms need 21V, AD converters sometimes need reference voltages much higher than 18V, audio amplifiers can need very high voltages, etc....

author: minime72706
author_rank: Frequent Contributor
timestamp: December 10, 2013, 10:54:49 pm
content: 24V is used by lots of different things including relays as well as HVAC systems.It's also nice having a 60V supply handy if you get bored and want to destroy somethingAlso charging up capacitor banks with 'legitimate' purpose!

author: G0HZU
author_rank: Super Contributor
timestamp: December 10, 2013, 10:59:58 pm
content: Quote from: be1212 on December 10, 2013, 09:49:15 pmIf it's a good quality 18V PSU then just buy it...At some point you will probably need a second and third bench PSU anyway. Also, you can make a basic boost regulator quickly and cheaply if you wanted to get more than 18V from your existing PSU. obviously, you won't be able to get the same max current from the boost reg but it's a cheap option and gives you TWO supply rails instead of one.

author: wilheldp
author_rank: Regular Contributor
timestamp: December 10, 2013, 11:26:47 pm
content: Quote from: minime72706 on December 10, 2013, 10:54:49 pmHVAC systems use 24 VAC, not 24 VDC.

author: minime72706
author_rank: Frequent Contributor
timestamp: December 11, 2013, 12:04:24 am
content: Quote from: wilheldp on December 10, 2013, 11:26:47 pmI'm aware but I was a bit out of it when I wrote that (laid down for a bit). Fine ... if you want to test something that is to be powered by a HVAC 24VAC/40VA transformer, you might want your power supply to go up to ((Line Voltage)/5)*1.414 or so (I infer that the transformer I have is just a 5:1 ratio because 120/24=5, but line voltage is not guaranteed to be 120VAC.)The resulting DC voltage is about 32V to 34V.BAM(For my senior project in college I made a thermostat with wireless temperature sensor nodes; the thermostat operated off of the 24VAC transformer and the sensors ran on LiPo batteries.)

author: prenato
author_rank: Regular Contributor
timestamp: December 11, 2013, 12:10:03 am
content: It really depends on what your interests are. In my personal experience with home-hobby projects, I rarely go above 18V these days. Furthermore, I would say 90% of the projects I've worked on are below 12V. Again, this really depends on what you are interested in...

author: AG6QR
author_rank: Frequent Contributor
timestamp: December 11, 2013, 12:18:45 am
content: I've got a 36V adjustable supply, and I can't remember the last time I had it over 18V. I know I've had it up high to test the supply and my meter, but other than that, I don't think I've had a practical reason to take the voltage up high. If you're playing with digital, computer stuff, radio stuff, and low power audio, 18V will probably cover your needs for quite a while.Yeah, RS232 uses +-12V, but I generate that from +5V using a MAX232.If you want to work with high power hi fidelity audio, you may eventually want a split supply of higher voltage.One other thing that comes to mind: Many laptop computers use a 19VDC input. Your 18V supply won't quite work to power one. That probably doesn't matter much, unless you're designing or testing laptops. Or if you lost the laptop's power brick, but in that case you should just go pick up another, rather than tying up your bench supply.Since you mention ham radios, note that they often use voltages much higher than 14V, at least internally. A typical VHF mobile radio transmits around 50W RMS into a 50ohm load, so it's got to be generating 50V RMS on its output, meaning the peaks must be about +/- 70V. But those typical VHF mobile radios only require input voltage of around 14VDC to generate that output. Transformers are wonderful things, no? Anyway, if you're going to power ham radios in the 50W to 100W output range, you'll want a high current supply of around 13.8 to 15V, maybe 15A or more. You don't need the full adjustability of a that bench supply. Horses for courses.But for general purpose digital and low power analog, 18V is very useful, probably more than enough. I'd go for it.

author: be1212
author_rank: Newbie
timestamp: December 11, 2013, 06:36:16 am
content: Thanks for everyone's thoughts. I can't think of any reason to not get it, so I will. I just wanted to double check that it wouldn't be limiting me in an obvious way. If it does, for example if I want to get into high fidelity audio, I'll just get another power supply. One can probably not have too many.

author: free_electron
author_rank: Super Contributor
timestamp: December 11, 2013, 06:47:53 am
content: A lab supply rarely needs to go above 15 volts....big power consumers on 12 or 24 volts are best supplied by a 'brick'.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: December 11, 2013, 07:40:11 am
content: A lot of pro audio circuits work at voltages above 18V. A single ended circuit can use a +30V or +40V rail. I find it useful to have the bench psu go up to 36 or 40V for these designs.

author: Rerouter
author_rank: Super Contributor
timestamp: December 11, 2013, 10:13:10 am
content: I have a solid 0-15V 3A supply for most general stuff and a +-35V 300mA (LM317 / 337) supply for the more oddball stuff, and a few hobby buck and boost converters for longer term hobby projects,buy what you can use now, and if you have some oddball jobs in the future that need 48V you can always hook your power supply in series with a plugpack, for some quick testing(a note on my +-35V supply, i have been bitten multiple times by thermal shutdown while testing something, and having brownouts while testing something just ruins your day until you become aware of it.)

author: Shock
author_rank: Super Contributor
timestamp: December 11, 2013, 04:11:26 pm
content: Something you may not be aware of, some dual and triple output lab supplies have a series mode this allows you to double the output.So a 2x 0-30V supply becomes 0-60V. This is not always advertised upfront. TheMastech HY3005F-3is one of them, no idea of the quality.I have such a supply that does 0-60V. At this voltage the output is considered dangerous so keep that in mind. As an alternative using a variac with a rectifier and filtering circuit, with a suitable transformer could power up almost everything you throw at it, if you don't need all the bells and whistles at higher voltage.