Good power supply kits - Page 1
Forum section: electronics / beginners

author: henryd99
author_rank: Contributor
timestamp: September 15, 2013, 02:26:52 am
content: hi i am kind of a noob when it comes to electronics design and i was looking to set up a basic electronics lab and i already have a soldering station and a multimeter as well as a small amount of components but i was wondering what else i am going to need i am basically know i need a power supply can anybody recommend any good power supply kits and i need a good breadboard so yeah and maybe an anti static wrist strap so i was wondering what else ill need and any recommendations will be greatly appreciated

author: nanofrog
author_rank: Super Contributor
timestamp: September 15, 2013, 04:15:02 am
content: If you're after a PSU kit, take a look at this:http://www.amazon.com/Elenco-Triple-Output-Power-Supply/dp/B0002DT0GUFor protoboards, you might want to look at Global Specialties (http://www.globalspecialties.com/premium-breadboards/proto-boards.html). A bit on the pricier side, but the contacts hold up a lot better & longer IMHO.ESD Ground Point (plug the wrist strap into this):http://www.ebay.com/itm/ESD-Ground-Block-Under-Bench-Common-Point-for-Anti-Static-Armband-Wrist-Strap-/111133282736?pt=LH_DefaultDomain_0&hash=item19e00f51b0#ht_4948wt_1161Plenty of sources on ESD straps on eBay (cordless = bogus if you're not aware). Sizes seem to be for small wrists though in my experience, so you might want to measure your wrist and ask before purchasing.__________________Indicating what you have could help.For example, it could help with the question of "What tools do you already have?".Do you have a rubber ESD mat? There's a seller in Canada that has decent prices (2 layer rubber, smooth; specify the color if/when you buy). Price depends on size. Example:http://www.ebay.com/itm/2-LAYER-RUBBER-ESD-MAT-24-X-48-W-GROUND-CABLE-/280739508681?pt=LH_DefaultDomain_2&hash=item415d60f1c9#ht_540wt_1161Please note, don't daisy chain the grounds (i.e. connect the wrist strap to the mat, then the mat to safety earth). Grounding block and mat ground both attach to safety earth (both of these wires will contain a resistor, typically 1M ohm). Connection is typically done via the screw that holds the receptacle plate to the wall (just make sure you get the paint off of the back of the screw so it's connected).BTW, in case you haven't seen this yet, it would be worth a look. Prices may be a bit higher since this was made, and there are some newer bits of gear out. But it's extremely relevant to the type of information you're after (entertaining too, so worth watching IMHO).There are other threads on this as well, so that could get you some additional info faster than waiting for members to see your thread and post.

author: rexxar
author_rank: Frequent Contributor
timestamp: September 15, 2013, 04:24:55 am
content: Quote from: nanofrog on September 15, 2013, 04:15:02 amI had trouble with this kit initially, it's not designed very well. Check outthisthread. One other mod I did was to replace R1 and R2 with 1/2 watt ones, as the original 1/4W ones burnt up under heavy load.Once I 'fixed' it, it turned out to be a great little supply. I've had a good experience overall with Elenco kits, they seem to be of reasonable quality for the price.

author: AG6QR
author_rank: Frequent Contributor
timestamp: September 15, 2013, 04:34:11 am
content: I've built the Elenco XP-720K kit, and can recommend it, with some minor reservations. Google will reveal a lot of information about it. You can find an assembly manual on-line. By the way, the assembly manual is very detailed and educational. I recommend downloading it and reading it first, even if you're only half-considering buying the kit.It's a standard very simple design. It has a 5 volt 3 amp rail powered by a LM7805 plus a pass transistor. There are dual variable rails, positive and negative, powered by LM317 and LM337 regulators. They each supply up to an amp at anywhere between 1.25 and 15V. The physical aspects are very sturdy. It has a strong metal case with large heatsink for the regulators. It's pretty heavy, mostly due to the transformer. There is plenty of extra space in the case to add minor modifications, and a web search will reveal a few ideas that people have implemented. I built mine using nice 10-turn pots instead of the standard pots that came with the kit.It has no adjustable current limiting, and no meters whatsoever.I really think an electronics bench ought to have at least one power supply with adjustable current limits and meters on both voltage and current. That's my biggest reservation about this supply. Also, the variable rails are limited to about 1 amp each, which isn't a whole lot of current. The supply does not make use of multiple taps on the transformer, so it will get hot if you try to draw a lot of current at a low voltage. Speaking of which, there may be times when you want to go lower than the 1.25V low limit of this supply, for example, to simulate a single rechargeable AA cell as it's being discharged.Since you mentioned power supply kits, this is one of the few supplies available as a complete kit, including the enclosure.Instead of this kit, I think most people will be well served buying a pre-built linear supply with adjustable current and voltage limits, and digital meters on both voltage and current. There are a number of these available from various sources. I already had a standard DC supply with meters and adjustable current limit before I built the XP-720. I built this kit because I wanted something with dual rails for op-amp tinkering. I'm very happy with it for the price. It's inexpensive, and delivers what it promises, but that's not a whole lot.

author: nanofrog
author_rank: Super Contributor
timestamp: September 15, 2013, 12:26:16 pm
content: Quote from: rexxar on September 15, 2013, 04:24:55 amIt's certainly not perfect, but the OP specifically was interested in a kit. And given another thread started by the OP, budget seems to be quite limited (i.e. $40 max for a soldering iron). And it can be improved to some extent as he learns IMHO.Seemed a reasonable recommendation given what was asked for and suspected financial conditions (gives something on hand to learn with).Quote from: AG6QR on September 15, 2013, 04:34:11 amAs a general rule, I agree.Not sure if the OP will be able to find a good one at the right price though, and he seems to be a bit anxious to get started.Personally, I'd rather go for a good used unit due to better construction (tends to be solid & have good heatsinking vs. what I've seen of some of the Asian produced units). Does require patience though to get a good one at the right price.

author: henryd99
author_rank: Contributor
timestamp: September 15, 2013, 02:35:41 pm
content: Thank you everybody for the info i will look into everything you suggested but im still kind of torn should i buy a pre built power supply or make my own

author: bingo600
author_rank: Super Contributor
timestamp: September 15, 2013, 03:30:41 pm
content: Your first PSU should be a decent one you can trustLike this onehttp://www.ebay.com/itm/Agilent-HP-E3610A-DC-Power-Supply-Dual-Range-0-8-V-3A-0-15V-2A-WORKING-/121173352795/Bingo

author: kizzap
author_rank: Unknown
timestamp: September 15, 2013, 03:37:58 pm
content: It depends on what you want to learn. If you want to learn how to make a power supply, do it. If your interests lie elsewhere, buy the power supply so you can work on the projects that interest you. Every electronics project you work on will take you into parts of design that you will not have experienced before.I wish you luck good sir!-kizzap

author: edavid
author_rank: Super Contributor
timestamp: September 15, 2013, 04:02:42 pm
content: Quote from: henryd99 on September 15, 2013, 02:35:41 pmI think you should buy one... there aren't any really good kits available, and even if you want to design your own, it's handy to have a working one while you're doing that.Here's another eBay deal:http://www.ebay.com/itm/HEATH-2718-0-20V-TRIPLE-DC-POWER-SUPPLY-VARIABLE-TRACKING-ANALOG-5v/181211519805for $42

author: rdl
author_rank: Super Contributor
timestamp: September 15, 2013, 04:14:06 pm
content: I really wouldn't advise buying a used power supply for someone new to electronics.Maybe I just have bad luck, but I've bought 3 HP/Agilent E3610A power supplies off eBay over the last couple of years and even though advertised as "perfect", "good working order", "functions correctly", etc, every one of them had some kind of problem or defect.Current limit not setting correctly, plastic binding post split in half, crack across the front of the CC Set button, massive voltage over shoot when first turned on, current limiting failing to engage for several seconds after set limit was exceeded, and so on.Some of these issues are not easily noticed at first unless thorough testing is performed with the right equipment.

author: henryd99
author_rank: Contributor
timestamp: September 15, 2013, 05:41:50 pm
content: ok ill take that into advisement but do y'all think that i really need two multimeters because i really cant afford another one at the moment and i was wondering were do i attach the grounding point to

author: henryd99
author_rank: Contributor
timestamp: September 15, 2013, 10:19:42 pm
content: do y'all have any psu recommendations in the 35 to 40 dollar range

author: rdl
author_rank: Super Contributor
timestamp: September 16, 2013, 12:30:50 am
content: I just checked on eBay and there are several LM317 based kits for $10 or less from China. They do have limitations, such as no current limiting and the capacitors may be a bit iffy, but you can still do a lot of learning and experimenting with this kind of basic supply. There was an Elenco XP-720 kit, unbuilt, on auction staring at 99 cents. Elenco also sells a cheaper XP-15 power supply kit that you can find on Amazon and elsewhere for about $25, some with shipping included.edit:I should add that those eBay kits don't come with a case of any kind and you have to provide your own transformer/wall-wart

author: kizzap
author_rank: Unknown
timestamp: September 16, 2013, 12:55:14 am
content: henryd99, what sort of things do you like doing in electronics? This will really dictate what we recommend. If you are just getting started and only have interests in arduino style/sized projects, you could possibly get away with a power supply board likethistill you really know what you need.

author: henryd99
author_rank: Contributor
timestamp: September 16, 2013, 01:02:01 am
content: well i am not going to be doing any high voltage stuff so i am really just going to be arduino sized stuff like you said

author: henryd99
author_rank: Contributor
timestamp: September 16, 2013, 01:35:36 am
content: do y'all think one of these would work and if it does how do i hook it up to the mainshttp://www.ebay.com/itm/NEW-LM317-Step-Down-DC-5V-35V-to-1-25V-30V-DIY-Kit-AC-DC-Power-Supply-Module-/251323818555?pt=LH_DefaultDomain_0&hash=item3a8411223b

author: pickle9000
author_rank: Super Contributor
timestamp: September 16, 2013, 02:30:34 am
content: First the kit looks fine but expect the quality of the components to be low. That said it's cheap you's be hard pressed to find a pcb for that much money so you have nothing to lose. You may want to add a voltmeter to it a cheap one is less than 5 bucks and makes setting the voltage much easier. Same rules apply a cheap meter like this onehttp://www.ebay.com/itm/1pcs-RED-LED-Panel-Meter-Digital-Voltmeter-DC-0-99-9V-new-/330813058644?pt=LH_DefaultDomain_0&hash=item4d05feae54isn't going to be dead accurate and may fail in the future but fun to play with.As for powering the board, you could use a wall wart, or maybe some rechargeable batteries if you need portability.The beauty of this kind of setup is that you can tear it apart later and use the parts things. Battery holders are always handy as are wall warts and rechargeable batteries.

author: henryd99
author_rank: Contributor
timestamp: September 16, 2013, 02:36:24 am
content: Thanks i think i will buy it

author: rdl
author_rank: Super Contributor
timestamp: September 16, 2013, 02:41:51 am
content: Here's one that's already built and the schematic looks reasonable except the LED won't light up if the output voltage is set too low and there's too much capacitance on the output. Looks like it has a fairly hefty heat sink also.http://www.ebay.com/itm/Power-Supply-Board-AC-DC-in-DC-out-Based-on-LM317-IC-/250499486450

author: creexpert
author_rank: Contributor
timestamp: September 16, 2013, 03:51:30 am
content: If you want cheap and decent.. prebuiltI purchased two of these and have not had an issue(less than $25 even less when you search the net for coupon codes)http://www.mcmelectronics.com/product/72-8790Hard to beat especially when you purchase during their $5 shipping sales

author: grenert
author_rank: Frequent Contributor
timestamp: September 16, 2013, 05:34:31 am
content: Quote from: rexxar on September 15, 2013, 04:24:55 amIf you've burned up R1 and R2, then you've done something wrong. That is basically a standard datasheet circuit. Those resistors only have the LM317/337 reference voltage (1.25 V) across them, so less than 10 mA current. The load should not pass through them.

author: henryd99
author_rank: Contributor
timestamp: September 16, 2013, 09:07:15 pm
content: Quote from: creexpert on September 16, 2013, 03:51:30 amI actually like this one i haven't bought the one i said yet and i think ill look into it