ElencoAC/DC Triple Output Power Supply Kit

Okay, there are a number of reviews here on Amazon that point out the cons of this unit. Allow me to say this about how the regulators are installed on the heatsink. The only way to keep costs down as well as build assembly simple, is to use this method. Other options would require active cooling with a noisy fan and internal heatsinks with pin guides for the PCB which for people new to kits like this (and Elenco designs this series for students), would increase difficulty. If you've never loosely stuck a TO pack to a pin guided heatsink (with thermal grease), then tried to tighten things up and solder in place, then finish screwing it in place before ( and that would have to be done four times in this kit), then this is a much simpler solution. All things considered I would prefer to have the individual heatsinks on the PCB, but I do get the design for cost and build simplicity. But as others have said make sure you heat shrink the exposed leads of each of the TO packs, so make sure to have some on hand.Now for the binding posts, there is no excuse. Elenco not only picked the cheapest posts they could find, when it became a problem they didn't bother to correctly address the problem. See a modern, quality binding post will be hard nickel plated on the post part but the area you attach the wiring will either be gold plated or bare, polished copper. Why? Because you can solder to gold or copper. You cant really solder to nickel very well. The reason they are fully nickel plated is because of costs. Nickel is a good electrical conductor (not great, but good enough), and really resists wear from the constant friction of plugging and unplugging of your leads. So thats a good thing. But when these cheap posts are made, they just plate the entire steel part in nickel instead of just the binding part and then polishing the internal hookup part as that is several extra steps that raise costs. So Elenco decided that on the 2010 revision of this kit to include 7 extra nuts but not add instruct the builder that they should just use the extra nuts to attach the wires in place with. Now the overall quality of the posts is fine, you just cant really solder the wires to them easily. Trying to use the extra nuts to bind them to the posts in cramped quarters is also pretty annoying. Run down to your local Radio Shack and pick up a $2.00 pack of 22 gauge ring terminals (catalog 64-3114) and use them instead. Just give yourself and extra half inch of wire on each of the binding post wires. Strip off one full inch instead of the 1/4" the instructions say. Double it over and solder it together. Then crimp it in the ring terminal and screw into place with the extra nut. Much simpler than trying to solder the posts or holding the wire in place in such cramped quarters.Other than that, the only parts I found that were just bad were a couple of caps. One of the 22,000µf and my 47,000µf were right at the very brink of their +/- 20% range, so I upgraded all my caps to new, high temp, low ESR caps that should last a good decade or two. Total price was an extra $7.00 with shipping. So if you can, check your caps before you build. You should be fine, but caps are cheap and good ones will last for a long time.A few do's and don'ts for the kit: Dont use the included lead free solder unless you have a tip and iron for lead free solder. Its hard to work with, it eats up your tip, and requires a good bit of excess heat. Do get some .20, .30, or .40 size 60/40 or 63/37 lead solder with a rosin core. When it comes to electronics, lead is indeed your friend. Don't use the included two pieces of plastic based heatshrink tubbing. Do get an assortment pack of different size heatshrink tubbing and use that instead. Heatshink all exposed contact points in the kit with individual tubes and not just one big one.This kit can be modded a bit. Like many who have built this kit, I chose to install a couple of 2k, 10 turn, wire wound pots to make fine tuning type adjustments. The simple carbon pots that come with the kit will work just fine. I just wanted more precision (ie fine tuning) when setting my voltages. If you don't happen to have a couple of these in your parts bin, then they will cost a bit. Upwards of $35.00 for two with shipping. That includes an extra few bucks for new dials since the included dials, wont fit most multi-turn pots. If you go this route, you will have to drill out the holes just ever so slightly more. We're talking just a hair or two.There is also plenty of room for a display to be installed in the company logo area of the front panel. I will be adding one in the future as I can see that checking my voltage every time with a multimeter will become a bit of a pain. I've already seen one kit where somebody installed a 20 x 4 line LCD display for this and it reads voltage and amps for all outputs.There is even a little extra room between the AC and DC rails for installing a load circuit, which I plan to do.So you can spend twice the price to upgrade this kit if your not careful. Keep in mind that most of these mods are just fun to add and helpful but are not needed. For that amount of cash you could just but a PSU with a display, and fine tuning built in. But the main reason to do it with this kit is it offers dual adjustable DC jacks at 1 amp, a constant 5v DC at 3 amps, and a 6.3/12.6v AC. You cant come anywhere near a quality tri-rail PSU at the $120-$130 mark. So the mods can be fun, useful, let you learn a little if your new to electronics and offer serious bang for the buck features that you would normally pay several hundred bucks for in a prebuilt PSU.The case and transformer are very well made and should last a very long time if treated with care. The taps on the transformer are made with silicone covered wire (which really surprised me) so they wont get brittle with age and heat like the common PVC types. The overall circuit is very simple, through hole based so if a componet happens to fail it would be an easy fix.All in all, its a great value kit that offers lots of upgrades options and should last a long time. I got it in January when Amazon was selling it for $49.00 (with prime), and I see that its now up to $59.00. That seems to be the average price online, so I dont think it will really go up more than this. I've put about $40.00 in parts and upgrades to it, and I'm very pleased with the end result. When I'm finished with future upgrades it will be about $120-$130 spent and I'll have a very versatile PSU, thats cool running, silent, and built to last. I give it five stars.***EDIT***Quick tip for building: Flux and tin ALL the PCB solder pads before you begin to populate the board. The solder pads on the PCB are beyond huge and if you try to solder components without the tinning, it will make the work much slower as it will take forever to heat up those large areas and leave your iron on your parts for to long. Don't forget to clean off any excess flux when you are done assembling the PCB.

This was perhaps my second or third soldering project and my first truly "serious" one (where the product involves significant current and AC power). I'm very pleased with the result. I should note that I didn't bother with the "lead-free" solder that came with the kit, and instead used time tested (and much easier to work with) 60/40. A good temp adjustable soldering station makes all the difference as well (I used a Hakko FX-888).Assembly was straightforward and the instructions were on the whole very clear, with only a couple of points where it took a few moments to puzzle out what was intended. As far as the assembly goes, the only tricky bits were when it came to the binding posts (required extra heat and flux to solder to), and the method of installing the ICs was decidedly "quick and dirty". That said, I suspect part of the reason it was done that way was to make it much less difficult to get the ICs installed and mounted. Getting them properly positioned onto a secondary PCB and then have them precisely match the predrilled mounting holes in the heatsink would have been significantly more fiddly than just soldering wires directly to the leads. As long as the wires are properly tinned and looped, and the assembly isn't rushed it's really not so bad.The lack of some sort of display is a slight disappointment, but adding one would only increase the cost and complexity of the kit so I fully understand why one wasn't part of the design.Everything worked perfectly on the first go, and all fell nicely within spec and tested as follows:Pos Var DC: 1.23v - 18.03v (spec calls for 1.25 - 15)Neg Var DC: -1.24v - -17.57v (spec calls for -1.25 - -15)+5VDC: 4.90 (acceptable range 4.75 - 5.25)12.6VAC: 13.77 (acceptable range 11 - 14)I enjoyed putting the kit together and am very happy with the finished product. In the future I'd even consider using the kit as a basis for another supply, but modified with a PCB for the ICs and the addition of a display. It's a great basic kit, but seems to have plenty of room for additional customization if desired.As is it's a solid, good value kit right out of the box.