Uni-Byte 217 - Versatile and Configurable DC LINEAR power supply - Part 1

[@iainmcculloch5807]

That's a great idea, but did you miss a connection on your bridge rectifier there?

[@uni-byte]

I did. Actually I connected the common to the AC instead of to the negative of the bridge. I corrected it when I made the layout of the board. Nice to see you're paying attention!

[@andymouse]

Yep, I'm a battery or linear guy whenever possible, I'm not a fan of switchers. Great vid !

[@uni-byte]

Thanks!

[@t1d100]

Great minds... I, too, thought of this critter, years ago, and I developed some different boards - DC to DC and AC to DC. Obviously, the major difference between the two is that the AC sourced unit includes a bridge rectifier and a smoothing cap. I got caught out on typically using two different brands of regulators... Yep, they have different pinouts = "Doh!" So, I like your solution of putting them in parallel. My AC to DC board also includes a negative rail. You have inspired a new revision = I think I will layout a universal board that will have three functions - Rectification, regulation and both positive and negative rails. Here's the trick; the function sections will be removable (by either snapping, or cutting, them off.) So, the user can have exactly what they need and remove the unused portions of the board to save space inside the case. Achieving this layout will be rather challenging and, therefore, much fun. I use the DC to DC boards to the (significantly) greater extent, to calm down noisy wall adapters. Like all the cool kids, I named the board = "Dr Dee's Old Tyme Wart Remedy." (Rights Reserved) They are extremely handy! Another thought provoking consideration for the universal board will be the means and types of input and output connections to include = barrel connectors, wire clamps, plain pin hole pads, etc. (The Wart Remedy has a 3.5mm Barrel Connector for its input and pin hole pads for its output.) Thanks for your efforts to share and teach!!! Cheers.

[@uni-byte]

Great idea for the switchable rail! I had thought of putting in a hole right beneath the terminal patterns to use as a strain relief for direct wiring .. but this was about 20 minutes after I got notification the boards went into production. I see a V2 in my future. I'll mention some of this when then boards get inI Thanks.

[@t1d100]

You mentioned that you like to use individual diodes to build your bridge rectifier. I can appreciate that. I prefer to use the All In One types GBU, KBU , Etc. series... Here's a tip = I bumped into a YT video of a man configuring four individual diodes to have the same pin pattern as the AIO types. He soldered them up dead bug style. That would look great, on the PCB = very retro steampunk-ish. I also saw one where the maker cut perf board into the shape of the AIOs and mounted the individual diodes on the perf board. So, if the PCB is made to use AIOs, and all you have on hand are individual diodes, there are lots of nice looking and functional means to create one. I also saw one where the dead bug style was bedded in epoxy putty. I am not sure what benefit they thought the putty would achieve, but, to me, it looked like the encapsulation would just retain heat and cook the diodes. Different strokes, I guess. HTH.

[@uni-byte]

Interesting ideas. Which thru-hole AIO pattern are you going to support on yours? I know of at least 3. The one in a DIP-8 sized package, the little cylindrical one with the leads in a square pattern or the linear one.

[@t1d100]

@@uni-byte The linear one is what I use most often - KBU1010 seems to fulfill all my needs... Sort of like the 1N4007 in discretes... Costs the same as the 1N4001. That seems to be true of the cost of the linear ones, as well. Same cost, no matter the volts rating. Cheers!

[@tiagoferreira086]

Using 2 regulators in parallel is not a good approach, a better (best?) approach would be to use a transistor to boost the current, if you google "7805 current boost" you will find some examples but there are some LMxxxx datasheets from Texas that have the calculations and such and you will be able to limit the max current through the regulator, you can use this technique for fixed and adjustable regulators. You can also use transistor with TL431.

[@uni-byte]

I'm not using two regulators in parallel. I'm using one or the other. if I only need 100ma or less I will install the 78Lxx, if I need over 100mA I will install the 78XX with various sized heatsinks depending on dissipation requirements and fnaly, if I do not need regulation at all I will install neiter type of regulator and place a jumper where the protection diode is. I also have a choice of rectification diode size and filter capacitor size to meet my requirements.

[@tiagoferreira086]

@@uni-byte I see, sorry, i clearly missed something, i was also working at a project while i was "watching" your video... Well in that case i think a tradicional lm317 with a pot would be a good candidate for the regulator, and a switch to bypass it instead of a jumper, about the capacitor maybe fit like 10, 47, 100, 470, 1000, 2200, 4700, 10000, with a double throw switch for each and a bleeder resistor when they are turned off.

[@uni-byte]

@@tiagoferreira086 I did give some thought to using LM317s, but these are intended for permanent installation and really not intended to variable. They are configurable, but do not need to be changeable. The goal was to make them as compact as possible while still allowing them to be versatile enough to be configured for a multitude of applications. Thanks for your thoughts on this!