Is 0-8volt power supply sufficient - Page 1
Forum section: electronics / testgear

author: drakke
author_rank: Regular Contributor
timestamp: February 16, 2015, 09:58:12 am
content: I can get a 8 volt DC power supply for relatively low cost.Is this sufficient for someone just beginning?What type of circuits will require voltages above 8v?

author: Obin
author_rank: Contributor
timestamp: February 16, 2015, 10:15:09 am
content: 8 volts could be a start.You'd be able to build circuits that would run on normal batteries in the future.But you could also save up a bit for a supply that provides 15 to 30V, that will keep you satisfied a lot longer

author: Kjelt
author_rank: Super Contributor
timestamp: February 16, 2015, 10:52:43 am
content: Important is that it has a current setting. This is a must for preventing disaster in case of shorts in your circuits

author: drakke
author_rank: Regular Contributor
timestamp: February 16, 2015, 11:09:53 am
content: Quote from: Kjelt on February 16, 2015, 10:52:43 amIt does have a constant current setting.Can I step up the voltage with a transformer if I need to or is this considered too much of a hack?Will it be stable and relatively low in noise?Thanks.

author: JVR
author_rank: Regular Contributor
timestamp: February 16, 2015, 11:17:39 am
content: Why not build one as your first project? For $40 you can build a dual supply capable of 0-30V from a transformer and LM317 and its negative counterpart

author: dom0
author_rank: Super Contributor
timestamp: February 16, 2015, 11:26:13 am
content: I'm no big fan of three-pin reg based "lab supplies". Building a proper one even from existing dimensioning and schematics is too hard for a beginner to get right at first, not to mention the need to work with 230 V.0-8 V is a typical lab supply for work on digital circuits and single supply analog circuits. It's a good starting point, IMHO - but it of course depends on what you want to do. If you want to do digital stuff: excellent. If you want to build audio amplifiers: a different supply will suit you better (e.g. dual supply).

author: dom0
author_rank: Super Contributor
timestamp: February 16, 2015, 11:26:58 am
content: Quote from: drakke on February 16, 2015, 11:09:53 am1. No2. Depends very much on the supply you want to buy, not on the voltage range.

author: drakke
author_rank: Regular Contributor
timestamp: February 16, 2015, 01:50:58 pm
content: Quote from: JVR on February 16, 2015, 11:17:39 amWhere would you start building your own PS?From a kit or a schematic?Can you point me to a good kit or schematic?Also what are the 'standard' textbooks on voltage regulation?

author: rollatorwieltje
author_rank: Unknown
timestamp: February 16, 2015, 03:03:27 pm
content: What power supply is it? 0-8V doesn't say much, for all we know it could be a welding transformer.An adjustable 0-8V bench supply with adjustable current limiter is quite useful for microcontroller/logic level stuff.

author: JVR
author_rank: Regular Contributor
timestamp: February 16, 2015, 03:05:07 pm
content: Quote from: dom0 on February 16, 2015, 11:26:13 am230V is hardly the end of the world, and if you work even remotely safely, you will be fine. Also, OP is in Mooseland, they use 110V don't they?Quote from: drakke on February 16, 2015, 01:50:58 pmI started from the LM317 datasheet, but look at these:http://www.electrokits.com/electronics/power-supplies/91.htmhttp://www.electrokits.com/electronics/power-supplies/85.htm

author: dom0
author_rank: Super Contributor
timestamp: February 16, 2015, 03:24:42 pm
content: Quote from: JVR on February 16, 2015, 03:05:07 pmStill, for a beginner I would never recommend to directly work with mains voltage. I'd always recommend to buy the first lab supply, it's not that expensive and you got a solid foundation you can build your stuff on.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: February 16, 2015, 03:57:17 pm
content: Quote from: rollatorwieltje on February 16, 2015, 03:03:27 pmI turned down a surplus 0-8 volt, 100 ampere transformer because I don't plan on doing any welding. He had three of them, and I toyed with the idea of buying them all and operating them in series until I considered what a pain that would be to adjust three voltage knobs, and get the current limits set correctly.

author: anotherlin
author_rank: Frequent Contributor
timestamp: February 16, 2015, 04:11:25 pm
content: Quote from: rollatorwieltje on February 16, 2015, 03:03:27 pmLOLAs for the original post, the question is rather : what you want to do with it ?If you plan to do only 5V digital electronics (stuff like microcontrollers), then a 0-8V supply is just fine.But for analog, a dual supply (let's say -15V/+15V) would be better.Also, what are the capabilities of this 0-8V supply ? How much power ? Does it have voltage/current metering ?On ebay.com, there's plenty of old but perfectly working HP power supplies, they can be scored for cheap.

author: jpb
author_rank: Super Contributor
timestamp: February 16, 2015, 04:34:18 pm
content: I'm not sure how useful a 0-8V supply is.It is too low for doing say analogue stuff especially if you're getting older stuff off ebay which often wants 12V or 15V.So it is to be used for digital, but why then have a variable supply? You probably want to have a fixed 3.3V supply and a fixed 5V supply which could be home build except perhaps for having the current limiting.Another alternative would be a fixed 12 V supply (a battery even) and then use linear regulators for 5V and 3.3V which could be done safely as home build as you'd only be working with 12V and then there would be the option for 12V as well for analogue stuff.The advantage of fixed supplies is that you're not going to accidentally connect a 3.3V logic circuit to an 8V supply or as I did yesterday, connect a sensitive 5V powered temperature sensing chip to a 12V supply and blow it up!

author: Seekonk
author_rank: Super Contributor
timestamp: February 16, 2015, 05:11:32 pm
content: I have a Xantrex 8V supply. It is rated at 80A. I only use for high current DC testing. It gets turned on about twice a year. Certainly worth it to me for that, sometimes you just need 50A. An 18V supply is the minimum you should consider and that is questionable.

author: drakke
author_rank: Regular Contributor
timestamp: February 16, 2015, 10:20:54 pm
content: Quote from: rollatorwieltje on February 16, 2015, 03:03:27 pmIt is a HP E3614A 0-8v, 6A, 48wI don't think it is very complicated.

author: drakke
author_rank: Regular Contributor
timestamp: February 16, 2015, 10:36:28 pm
content: Quote from: jpb on February 16, 2015, 04:34:18 pmYes it seems pointless to get a variable PS with only 8v.I'll use it for digital circuits and get another one later.I bought it used locally for $100.

author: dom0
author_rank: Super Contributor
timestamp: February 16, 2015, 11:11:44 pm
content: The HP E3614A is a very good supply. 100 USD is an appropiate price for it.

author: SkyMaster
author_rank: Frequent Contributor
timestamp: February 17, 2015, 01:56:55 am
content: drakke,Congratulations, you bought a very good Power Supply.Quote from: drakke on February 16, 2015, 10:20:54 pm