EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: zippy500 on December 17, 2013, 02:01:02 pm
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Hello,
my first post sorry if it's in the wrong topic section
Want to start out in hobby electronics.
Just wondering which (cheap)power supply to get was looking 0-15v
But someone said that I should get a 0-30v.
Just starting out so not looking to spend loads of money, do I need a variable
One, was looking at converting a Atx PC power supply??
came across a tattoo power supply they have variable voltage quite cheap, can these been adapted to use maybe?
Any views are welcome.
Thanks
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I would suggest you convert an ATX power supply to a bench supply with some banana jacks.
If you want to add an adjustable output voltage you can use an LM317 (LM117 for negative rail) and a 10 turn pot. It's a very basic and easy to understand circuit for a beginner to build.
Watch out with the ATX power supplys though, they really do have quite some beefy outputs so beware of shorting them out (especially to the grounded case).
Also note that ATX supplys are mains earth referenced, i.e. you can't use two ATX supplys to make a +5V/-5V supply for example.
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I have 2 Power Designs supplies on my bench; can't beat the price (~75$ each shipped!) and they are built like tanks. There's on on ebay now a 0-20V precision one (500mA only however); a bit pricey compared to a ATX conversion, but a very good supply!
eBay auction: #121236662123
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Welcome to the forum! Going to your personal profile and setting your country will help you get input that is relevant to where you live. Your country flag will show up on your posts.
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many thanks for your replies,
I am still curious about this tattoo power supply would this work they seem quite cheap as well.
Is a 0-15V sufficient or should I go with a 0-30v?
thanks
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I use a 5V regulators quite a bit, so 10-12V supplies are more than enough for me. Occasionally I like to have the extra headroom to experiment with. I would think 0-15V would be enough to start with.
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All depends on the demand you place on a power supply.
Just for basic electronic tinkering you do not need anything fancy with lots of current output.
The LM317 and LM337 are perfect for something lightweight, for example:
(http://i.imgur.com/6NlHT6C.jpg)
It's really easy to build. Your choice, either just one of them or all four.
The internet is full of appropriate schematics.
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The first and I think most important thing you should ask yourself is what I wanna build... I have one quite precise linear power source 15V/1,5A that I've made mysef like 12 years ago (I was 14). It's still good and it was enough for most things I've done so far (especially apps driven from 9V bat, one 12V source, 5V logic apps etc.).
I have some other power sources, with fixed voltage, that I use for other stuff (especially when symetrical voltage is needed, something like -15V - +15V is really necessary, when power is needed, something like 12V/5A will do).
So, if you wanna play with logic, uC and uP, low voltage stuff, etc. You want something like 0-15V about 1Amp.
If you wanna play with audio, symetrical source would be better.
If you wanna build stuff with some mechanical parts (motors, servos), or from discrete components (I'm not sure if anybody does that anymore) you would need something like 0-30/3A.
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Make one , what a nice way to get into electronics.
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Plenty available, new or used.
As others have indicated, you might want to build one instead (nice learning experience). Plenty of articles and schematics available on the internet.
Regarding the tattoo psu, can you provide a link or specs for it?
Assuming it's 0-15V, ~1.5-2A, it should be usable (i.e. linear type, with an adjustment pot; preferably 10 turn as single turns are too hard to get the voltage adjusted where you want). Pot could be replaced if necessary.
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Something like this seems to have the spec for a basic supply unit
http://www.lightinthebox.com/Professional-Dual-Digital-LCD-Tattoo-Power-Supply_p81429.html?currency=GBP&litb_from=paid_adwords_display&gclid=COi13IWkubsCFWmWtAod_H8AoQ (http://www.lightinthebox.com/Professional-Dual-Digital-LCD-Tattoo-Power-Supply_p81429.html?currency=GBP&litb_from=paid_adwords_display&gclid=COi13IWkubsCFWmWtAod_H8AoQ)
What do you think?
I'm the fool who buys lots of rubbish to save money then goes and buys the right one in the end!!!
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It looks like an awesome supply if you want to continue your way of doing things (buy rubbish first, then buy something better).
You may want to come up with a better way of connecting your wires to it than using those plugs.
There is no current meter and no way to limit the current, but don't let that stop you. It only makes it slightly easier to fry your circuits when you connect something up wrong :)
And, as a bonus, you get a footswitch!
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I would plan on adding binding posts and an output fuse (in a panel fuseholder).
Since the tattoo supply is not intended for electronics experimentation use, I would check for continuity between the output and earth. The output may not be floating.
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No one has mentioned the main feature of a power supply you need - it's not voltage range or max current, it's adjustable current/constant current mode.
This is an invaluable feature for any beginner as it lets you to power your new design safely without possibly destroying it. Just set current to zero, connect your stuff and start carefully increasing the current - if you start going over expected/reasonable value - switch off and debug.
I've got myself a basic Chinese "McPower" branded supply defective off ebay. Replaced the dead opamp, now it just works. The supply price range is somewhat 50$/euros, it's crap from precision and regulation standpoint, but does the job.
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Totally agree about current limiting. By the way I recently bought a Farnell LT30-2, 2 x 30v @ 2A bench power supply from eBay for just 24.99 GBP. Most useful features for me are current limiting and having the two separate supplies.
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Have a look at these people, they are fairly good and the prices are reasonable.
http://www.circuitspecialists.eu/power-supplies/bench-power-supplies (http://www.circuitspecialists.eu/power-supplies/bench-power-supplies)
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As you are in the UK, keep an eyeball out for your local Maplin store.
I got this http://www.maplin.co.uk/p/100w-slim-bench-power-supply-n93cx (http://www.maplin.co.uk/p/100w-slim-bench-power-supply-n93cx) for only £49.99 when it was on offer (usually £89.99). They have had it on sale a few times since, so look out for the January sales. 20V / 5A and the important current limiting feature. The negative is floating/isolated from earth ground too.
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Have a look at these people, they are fairly good and the prices are reasonable.
http://www.circuitspecialists.eu/power-supplies/bench-power-supplies (http://www.circuitspecialists.eu/power-supplies/bench-power-supplies)
All their PSUs are rebadged. They don't do much to hide the fact and they usually have a reasonable selection. However, the current selection includes the CSI 3003 SM, CSI 3005 SM and CSI 3010 SW. At least the first two are Ningbo Jiuyuan (aka QJE) switching mode power supplies PS3003M and PS3005M. They have horrible specs. 200 mV pp ripple, very large output caps subverting any current limiting, and more quirks. IMHO not worth their money.
The linear ones, some of them also from QJE are more reasonable, typical Chinese power supplies.
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Their old stuff was a bit better.
I have one of their older linear PSUs and its a rebadged Array.
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My vote is to build one. There is no more rewarding way to get started in electronics then putting together your own equipment. The following YouTube video is a great start.
http://youtu.be/2EFnqZUxFZ4 (http://youtu.be/2EFnqZUxFZ4)
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Most useful features for me are current limiting and having the two separate supplies.
I will second the two supplies... I have two single output bench supplies, but that gets awkward when you have a widget that you want to power and it requires two different voltage rails and you want to power them both from bench supplies... some devices can't deal with the rails coming up at different times, so a dual supply can be most useful in these cases).
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You can search for a regulated CV/CC power supply with constantly adjustable voltage/current. There should be a lot of budget power supplies from Ebay/Amazon or any other online stores.
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Usually a selection of decent, used power supplies (single to triple output) on eBay. Something to consider at any rate.
Recently picked up a Power Designs TP343B for ~$82 shipped (triple output model). Far more unit for the money than can be had new.
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I am about make one mine will be a bit more complicated but you can use the LT3080 a 10turn pot and a cheep panel meter from eBay and I got a nice enclosure rom maplin for it. Doing it using an enclosure men's you can use strip board and ad currant limiting later if you want you should do this using a deferential opamp across a currant shunt and a comparator. So you don't need to play whith dangerous 240v you can use a high power laptop power supply or an atx power supply whith the 12v going to the voltage regulators but this doesn't give you much voltage range. I would recommend a 24v laptop power supply
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Set up an ebay search for old HP E361XA supplies. When you see one for $80 or less, jump on it.
Then use it to make your own :)
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Try this
http://www.rapidonline.com/Electrical-Power/Rapid-18V-Dual-LCD-Meter-PSU-74610 (http://www.rapidonline.com/Electrical-Power/Rapid-18V-Dual-LCD-Meter-PSU-74610)
Or one of these:
http://www.rapidonline.com/Electrical-Power/Voltcraft-Single-Output-100W-DC-Power-Supply-526006 (http://www.rapidonline.com/Electrical-Power/Voltcraft-Single-Output-100W-DC-Power-Supply-526006)
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Anybody have a link to a kit that has CC & CV capability? I can solder but certainly can't design one. At the very least I would need a ready PCB.
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I would highly recommend to have a decent look into used HP/Agilent Power supplies. They sell for less than 200 $ and are built like tanks.
Either the supply-only units of the E361XA series as mentioned before, or the source-sink units of the E663XB series.
I recently bought two of those (http://www.ebay.com/itm/251427296029 (http://www.ebay.com/itm/251427296029)) and I'm pretty happy with them. Power suppy and electronic load in one, remote controllable, 0-20V, 0-5A (sink and source).
Built quality of these is awesome, not to compare with cheap and/or self-made units.
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I bought a Tenma 3 channel PSU
http://uk.farnell.com/tenma/72-10505/psu-bench-triple-3a-30v-5v/dp/2251949 (http://uk.farnell.com/tenma/72-10505/psu-bench-triple-3a-30v-5v/dp/2251949)
it seems good to me, and is easily available in UK