Project files: Universal Triple-PSUs

What is it?
Two boards for general-purpose LM317/LM337 power supplies with three rails, useable for many low-power applications where both a +/- supply and an auxiliary voltage are needed. Examples include analog amplifier + digital/logic circuitry, microphone preamplifier + phantom voltage etc.
There are two versions, one where the +/- voltage is derived from a single AC-voltage via a doubler and one where it comes from a traditional two-bridge rectifier circuit. This design is virtually a copy of my GP-PSUs. I made some minor enhancements and added the extra rail, but it is the same basic design.

How big are the boards?
Both board versions measure 3.925″ x 2.6″ (app. 100 x 66 mm.) and they are mechanically interchangeable.

What is the status of the boards?
The “standard” board is in v1.0 and works fine. The voltage-doubled board is in v1.1 and also works fine. The two versions are completely identical except for the diode/bridge arrangement on the +/- supply. The difference in version numbers came because I originally prototyped a different (smaller) layout for the voltage-doubled version. After making the “standard” version that requires a bit more space for the rectifier bridges, I decided it was smarter if they were both the same size and then changed the layout of the voltage-doubled board to match.

Does it use any special/expensive/hard-to-find parts?
Nothing, really. As always with these circuits, you can use standard LM317/337 regulators or splash out on more expensive (low-dropout) types like the LT/LM/LD108x-series. My experiences with the latter parts aren’t the greatest though (instability), so unless your applications require the low-drop capability I’d just as well stick to standard 317/337-types from a reputable source. If your application requires higher performance than this, you are probably better off looking at entirely different circuits and regulators.

Anything else I need to know?

  • There is a jumper on the boards that links the ground on the AUX-voltage to the midpoint (0V) of the +/- supply. This is optional and probably not required for most applications but can be used for e.g. linking analog and digital ground in mixed-signal circuits.
  • The diameter of the main filter capacitors is 16mm on the AUX supply and 18mm on the main supply.
  • The DIP rectifier bridges exist in versions up to 2A rated current although anything more than 1A can be a bit difficult to find. Realistically though, if you plan on drawing more than 1A from either supply the SK104-type heat sinks are probably going to be a limiting factor anyway.
  • Mounting the regulators and heat sinks is a bit of a faff because there is not much space, especially if the heat sinks are 38mm or taller. My suggestion (as always) is something like this:
    1) Loosely assemble the regulator, the isolation components and the heatsink.
    2) Mount the combination on the PCB and solder the heatsink in place.
    3) Tighten the screw holding the regulator to the heatsink.
    4) Solder the regulator in place.

Downloads:
Download design files here

Related information:
Even though the regulators used here are generic types made by many manufacturers, there can be small differences in recommended parts values etc. I suggest you always consult the regulator data sheets from the specific manufacturer.

Note: Always read the “intro post” for additional important information about my designs.

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Project files: Little helpers – Powerhelpers

What is it?
A few auxiliary boards to match the mainscontroller boards or for use one their own. More specifically, there are a couple of relay boards for use with the relay-less version of the Mainscontroller. The large relay board is intended for a “T90”-type relay which is typically rated 20/30A. The smaller board is using a Omron G5LE relay which is rated 6/10A.

There is also a simple softstart-board that can be used when powering transformers over app. 250-300VA. This is based on a very old (and frequently copied) circuit from Elektor that seems to work well, at least for medium-sized PSUs.

How big are the boards?
The Softstart board and the large relay board are both 2″ x 2″ (app. 51×51 mm.). The smaller relay board measures 1.5″ x 2″ (app. 38 x 51 mm.) As the pictures show, mounting holes and connectors line up so the boards can be stacked and cables routed neatly between them.

What is the status of the boards?
The softstart board is now in v1.5 as it is an improved version of one I did earlier. The large relay board is v1.1 as I have prototyped it and corrected the relay footprint which wasn’t perfect (my own design, obviously…). The small relay PCB is in v1.0. I haven’t actually received and tested the prototype boards yet, but as it is the exact same circuit as the large board and the footprint for the relay is an eagle standard one I am OK with releasing this design as well.

Does it use any special/expensive/hard-to-find parts?
Not really, but:

  • The T90 relays can commonly be found on ebay. There are name-brand equivalents as well from Omron, Finder and other manufacturers of relays.
  • The Omron G5LE can be puchased cheaply from Mouser or Reichelt. Alternatively there are equivalents available on ebay, usually marked with SRD-xxx designations.
  • The relay on the softstart is an Omron G2R-24V type which is also available from Mouser or Reichelt.
  • Note that the large 330nF capacitor on the soft start board must be an X2-rated type.

Anything else I need to know?

  • When in use, these boards may feature exposed mains parts (the softstart certainly will). One especially “problematic” thing is that the legs of the axial resistors are partly exposed so make sure that the board is protected from accidental touches. If you are stacking boards, I suggest putting the relay PCB on top as it has fewer exposed parts, but even so a cover** of some sort could be a good idea.
  • Whether used with the Mainscontroller board or on it’s own, be sure that you are aware of the current consumption of the mechanical relays. The T90 relay typically consumes app. 1W (1200 mW worst case) and the G5LE relay consumes app. 400mW, which for instance means they cannot be controlled directly by a micro controller.
  • I have never tested the softstart board on transformers larger than 500VA. I imagine it should be good up to around 800-1000VA, but anything more and I would be cautious and probably look for something with bigger relays and resistors. The same applies if you are using exceptionally large capacitor banks.
  • **The cover is based on an idea I had a while ago but didn’t test until now: I wanted to have an easy way to make covers to shield sensitive and hot/live parts from touches. I could use Front panel express to have 2mm acrylic sheets made but that is comparatively expensive, so I came up with another way: The Gerber files give me the board outline for each design and so by rendering the Gerbers e.g. with Circuitpeople I can get a true-size outline. Once that is scaled I can then import into a graphics program to add warning symbols, text or anything else. To get the cover I simply laminate the printout using a home laminating machine with the thickets foil type and then use a hole punch to cut out the mounting holes which are clearly marked. It’s obviously not a safety-approved material in any way, but it fits perfectly and it will protect against accidental touches which is bound to be better than nothing.

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: Mains controller with offboard relay

What is it?
A version of my Standby-PSU & controller for applications that need to switch very high (or very low) currents, switch multiple relays or simply prefers to use an offboard relay, be it mechanical or SSR. A couple of matching PCBs for relays and a soft start will follow very shortly, I just need to process the pictures and finish the write-up. This is basically the same circuit as the “v1.5” of the standbyPSU (found here) without the onboard SSR.

How big are the boards?
This version measures 3.2″ x 1.875″ (app. 81 x 48mm) – so just a little smaller than the v1.5.

What is the status of the boards?
This board is v1.0 and it works as expected – not entirely surprising given that it is mostly identical to the v1.5 circuit which also worked well.

Does it use any special/expensive/hard-to-find parts?
No.

Anything else I need to know?
Note that big mechanical relays tend to draw a lot of power, so there might not be that much power left over to power anything else. As an example, the relay board that I will post later draws app. 1.2W. Throw in a couple of LEDs and the losses in the transformer, and there isn’t actually that much left over from the 2.5-3VA transformers that are the maximum that will fit on the board. You can of course use the controller to control a separate standby-PSU as well.
If you want to use an SSR, then be aware that they can be a bit tricky to work with and some attention must be paid to minimum load etc. I can recommend reading this document from Omron that explains a lot.

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

You can also read the other posts on this controller design for information.

Project files: SLA battery charger

What is it?
For one of my work-in-progress builds I needed a simple charging circuit for an SLA (sealed lead-acid) 12V battery. So, good excuse for another project 🙂

Compared to the Li-Ion or LIPo-batteries used in most applications today, charging an SLA is extremely simple. You use a fixed voltage and then set a limited charge current of around 1/10C or a trickle-charge current of around 1/20C and off you go. (“C” is the nominal capacity of the battery, so 1/10C for a 7Ah battery is 700mA).

A bit of searching online turned up a few suggestions but one appealed more to me than the others, mainly because of its simplicity. The circuit is built around the L200 voltage regulator which features programmable voltage- and current limits, which is exactly what this application calls for. I believe the original circuit is from Elektor, but I am unable to find it so I relied on the web versions here and here instead.

How big are the boards?
The board measures 1.95″ x 1.6″ (app. 50 x 41 mm) without the heat sink.

What is the status of the boards?
The published version of the board is 1.1. Changes from the prototype v1.0 that I built are fixes for some misprinted LED-labels (doh!) and some minor touch-ups to the silkscreen – nothing major.

Does it use any special/expensive/hard-to-find parts?
Not really. Just be a bit careful checking component dimensions against board footprints because there isn’t much space left over.

Anything else I need to know?

  • The PCB is meant for currents smaller than 1A due to the limitations of the rectifier and protection diodes. With a bit of searching it is possible to get 2A components that fit, however whether this is a good idea from a thermal POV remains to be seen.
  • The component values are normally meant for 12V batteries (and a 13.8V charging voltage). A few of the articles have component values for 6V battery use as well, but if anyone can easily recalculate for 24V (2 batteries in series) please let me know.
  • The L200 regulator must be heat sinked, but how much depends on charging current and input/output voltages. The one on my picture was the only one I had with pre-drilled holes, so don’t take that as a recommendation/indication in any way 🙂
  • Although not shown, fuses should always be used in series with the charging battery. An SLA battery is capable of some truly terrifying short-circuit currents, so there should always be a fuse to protect the circuit from damage.

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: Little helpers – Fuseboards

The third part of my “little helpers” project series consists of a few connector/fuse boards for power supplies or for testing/lab use. Not exactly the world’s most interesting PCBs, but still  – they can be quite useful so I decided to publish them anyway 🙂

What is it?
These are simple fuse-boards with LEDs to be used on the secondary side of a transformer or DC PSUs (such as switchers). There are two versions:

One version can be used to combine two AC or DC voltages to provide a center-tapped voltage. The circuit works on both AC and DC so can be used for example for wiring up two secondary windings on a transformer to provide a +/- voltage or for combining two DC power supplies to do the same.

The second type of board is more or less identical, except that the ground plane is split so they are “passthrough” for the input voltages. This is useful for instance if you want to put fuses between the transformer secondary and a PSU board that already has an onboard rectifier and does not need (or want) a center-tapped voltage.

The boards also include fuses for both rails as well as LEDs to indicate that power is applied. If connected in the “standard” way then the LEDs are connected to the input through the fuse, so if the fuse breaks the corresponding LED will turn off.

How big are the boards?
There are two sizes of both designs:

  • The “small” one measures 2.0″x1.95″ (app. 51x50mm)
  • The “normal” one measures 2.5″x1.95″ (app. 64x50mm)

The two versions are compatible, meaning the board size and hole spacing are the same for the two versions.

What is the status of the boards?
All boards are in v1.0, meaning they have been tested and are working. (Well, to be honest I haven’t received the prototype versions of the “passthrough” boards yet, but as they are made from the schematics to the other ones I expect no issues) 🙂

Does it use any special/expensive/hard-to-find parts?
Not really. The fuses are standard 5x20mm types with holders (22.5mm lead spacing). The LEDs, resistors and diodes are all “standard” types and the terminal blocks are 5.0/5.08mm types.

Anything else I need to know?

  • On the large boards it should be possible to use PCB-mounted FAST-ON tabs instead of the terminal blocks (not tested though).
  • Note: These boards are not intended for mains voltage use!

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: Mains controller v1.5

What is it?
As promised in the original post, an update of the Mainscontroller design to v1.5.

This is the transformer-based version 1.1 which I have tweaked a bit. There aren’t really any functional changes but I cleaned up the layout a little and included some things from the rev. 2.0 such as a “”proper” terminal block for the switched DC output. Also, two versions are included, one with an onboard fuse and a single output connector, the other without the fuse and with two parallel outputs instead. The holes are compatible between the versions and all parts except the output connectors and fuse holder are identical between the two versions.

There are some minor tweaks to the included BoM as well, mainly the addition of values for a 9V option but also tweaks to some resistor values for more consistent operating points between the versions.

How big are the boards?
Both board versions measure 3.7″ x 1.875″ (app. 94 x 48mm) – the same as the older v1.1.

What is the status of the boards?
As mentioned, this is v1.5 of an already tested design. I have built one copy of the single-output version and it works as expected.

Does it use any special/expensive/hard-to-find parts?
Compared to the original v1.1, no.

Anything else I need to know?
If you’ve read the comments in the original post, then no 🙂

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: The ManyCaps PSUs…

What is it?
A little sideline project one might say :). For one of my other (upcoming) projects I needed to buy quite a few Panasonic FM series capacitors in one specific value. As is sometimes the case, buying 100 wasn’t much more expensive than just buying the 35 I needed and so I ended up with a question: What can you do with the rest?

In theory, paralleling multiple small capacitors gives you lower ESR/ESL and higher ripple current than a single big cap. However, due to the physical distance required between the many small caps some of the benefit is negated and overall I am not sure I dare say that one approach is inherently better than the other – that depends on what you are trying to achieve I think.

However, as I already had the capacitors I might as well try it. Obviously, something as groundbreaking as this needs to have a suitably audiophile-sounding name, so without further ado allow me to introduce the “ManyCaps”(™) audiophile PSU boards 😀

There are two versions, single and dual, with space for either 2×12 or 1×15 13mm radial capacitors. The most obvious application for these is probably gainclones and smaller class D amplifiers but they can be used anywhere where an unregulated supply is OK. The boards can of course also be used with a DC input, either with the rectifier in place or with the rectifier bypassed.

How big are the boards?
The single board measures 3.8″ x 2.0″ (app. 97 x 51 mm) and the dual board measures 3.925″ x 3.2″ (app. 100 x 81 mm).

What is the status of the boards?
Both boards are in v. 1.0. They are simple designs, so I didn’t need to make any changes and they worked the first time round 🙂

Does it use any special/expensive/hard-to-find parts?
Nothing really stands out:
  • The main capacitors are 13mm max diameter and voltage obviously depends on the application.
  • Rectifier is GBU-type and should probably be rated at least 6-8A.
  • The decoupling capacitor should be around 1.0 uF MKP or MKT. The lead spacing is 22.5mm on the dual board and 15mm on the single board.

Anything else I need to know?
Can’t think of anything 🙂

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: Mains controller & standby PSU

What is it?
These are the project files for my mains controller and standby-PSU shown here. Also included are the files for a simple standby-PSU without any control logic for a MeanWell IRM-series power module from 5-20W if you just need an AUX-voltage (or a very simple single-rail PSU).

As mentioned in the original post I am not completely happy with these inasmuch as I haven’t really been able to get to a “one-size fits all” version. However, as both versions work (and should work well in the right application) then I am posting the files anyway. You should probably use the transformer version if you need 5V power for logic circuitry because they output is well-regulated. Max. DC output capability is probably around 250-300 mA for supporting circuitry if you subtract the power drawn by LEDs and the SSR etc. (assuming a 6VAC EI-30 transformer is used). For 12V out with a 12VAC transformer, you are probably closer to 150-200 mA as the limit. You should use the IRM-based version if you need more power, such as 12V/24V for fans etc. With an IRM10-12 power module you have around 12V/800mA to play with – plenty for even large fans and other supporting circuitry.

Note: If you are interested in the transformer-based version you may want to hold on for another couple of weeks as I have a “version 1.5” of this on order. Same transformer and same board size, but a few layout tweaks that should make the board more usable.

How big are the boards?

  • Transformer version: 3.7″ x 1.875″ (app. 94 x 48 mm)
  • IRM-version: 3.625″ x 1.75″ (app. 92 x 45 mm)
  • Separate IRM PSU: 2.95″ x 1.25″ (app. 75x32mm)

What is the status of the boards?
The transformer-based version is in version 1.1. The only change from v1.0 is that I changed the lead spacing for the snubber capacitor from 5mm to 7.5mm so that a proper X2-rated part can be used.
For the IRM-version, the files are the same v2.0 version that I built and showed in the original post.

Does it use any special/expensive/hard-to-find parts?
Not too many 🙂

  • The snubber cap across the SSR must be 7.5mm lead spacing and X2-rated. Mouser has them and you may be able to get them from elsewhere as well.
  • The SSR can be had from many sources, including Reichelt, Mouser, ebay etc.
  • The transformer is a fairly common EI30 type which can also be bought from many sources such as Reichelt, TME etc. Note that EI-30 is, strictly speaking, only the core type of the transformer. Always confirm dimensions and pin connections etc. against the manufacturer’s datasheet before you buy.
  • If you want to build the IRM-version then the IRM module itself is a bit expensive. Mouser has them, but if you are in Europe then TME is actually cheaper although at the time of writing this their stocks are a bit erratic.

Anything else I need to know?

  • The connections are quite simple:
    – Mains: For AC input.
    – Load: For the device to be turned on by the SSR. On the IRM-version there are two outputs, but they are in parallel so it does not matter which one is used.
    – Switch: This is the “main” trigger. Short the “trigger” pin to the positive rail via a latching switch to turn on the SSR.
    – Test: This is a shorting jumper for testing purposes. Shorting these two pins turns on the SSR. While intended for testing, you can also use it as an extra trigger, especially if you want galvanic insulation between the logic circuit and the SSR trigger – simply use an optocoupler where the secondary side transistor shorts these two pins.
    – Ext: This is for turning on the SSR via an external circuit, i.e. microcontroller or other logic signal.
    – DC out: This has DC output at all time when the board is powered on.
    – DC switched: This has DC output only when the SSR is turned on.
  • I normally do not post BoMs with these circuits, but this time there’s one included since it may not otherwise be logical how to choose the right parts. The BoM is correct as far as I can see, but if you believe you have found an error or if you have a question you are welcome to contact me.
  • Lastly: Always remember that this circuit is mains-powered. Be careful when building, testing and mounting it and always respect your local electrical code of practice. In short: If you’re not sure what you are doing – then stop and ask someone who does!

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Project files: DC-DC converter boards

What is it?
PCBs for DC-DC converters as described here. There are three sizes, for 1”x1”, 1”x2” and 2”x2” converters respectively. These footprints are industry-standard so you can use converters from a variety of manufacturers such as Traco, Recom, Murata and many others.

How big are the boards?

  • 1”x1” PCB: 1.875″ x 1.475″ (app. 48 x 38 mm)
  • 1”x2” PCB: 2.85″ x  1.475″ (app. 72 x 38 mm)
  • 2”x2” PCB: 2.85″ x 2.5″ (app. 72 x 64 mm)

What is the status of the boards?
All the boards are in version 1.1, meaning they have been prototyped and minor tweaks made to silkscreen etc.

Does it use any special/expensive/hard-to-find parts?
The ceramic caps between the primary and secondary sides should typically be rated for 2-3kV which can be a bit difficult to find. Mouser/Digi-key obviously have them but your local parts suppliers might not. Otherwise, apart from the converter itself, not really.

Anything else I need to know?

  • The external components are for EMI filtering and (usually) not required in order for the converter to work. All the caps on the primary side have 1812 SMT footprints.
  • The two component positions on the secondary side can be used for decoupling (required for stability with some converters) or for voltage trim if your converter supports that. These have 1206 SMT footprints.
  • Not all converters have enable-pins and some has the functionality, but wired as “always-off” instead of “always-on”. In this case you need to wire the enable-pin to the negative input voltage in order for the converter to turn on (you can of course also use the optocoupler here, but with the logic inverted).
  • If you use a 4:1 input range converter and you expect to actually use that input range, you need to be a bit careful with the value and power rating of the LED resistor, at least on the two small boards. Both the LED and the resistor are 1206 SMT here. On the 2”x2” board you can fit a 1/2W or 1W leaded resistor and then there should be no problems.
  • Many converters are sensitive to the capacitive loading on the output, so remember to check the datasheet for maximum allowed capacitance. If you exceed this limit it is possble that the converter will refuse to start up.
  • You can sometimes find DC-DC converters as cheap surplus items. Normally that is absolutely not a problem, but remember that even if the footprints are industry standard there can be quite a few differences between manufacturers. I recommend that you do not buy anything that is so obscure that you can’t google your way to a datasheet/application note for it 😀

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Always remember to refer to the manufacturer’s datasheet and application notes for specifics on pin connections, external component values etc.

EDIT 20-08-2014: Added comment on capacitive loading.

dcdc-3

Project files: High current regulators

What is it?
These are high-current regulators designed for LM/LT108x-type regulators with current limits up to 5A or 7.5A dependent on the package. There are two versions, one with an on-board heat sink (as used to power the JLH1969 here) and the other without an onboard heat sink. The PCB with heat sink is intended for regulators in TO-220 packages. This will give you up to 5 amp current capability with an LM338 or a LM/LT1084 reglator IC. The PCB without heat sink is intended to use a TO-247 packaged regulator (LM/LT108xCP – up to 7.5A output current) and should be mounted on a suitable heat sink instead. Whether you use one or the other board version, remember to always calculate the heat dissipated in the regulator – if you are expecting to draw a couple of amps or more, the heat dissipation in the regulator quickly becomes quite large.
Also included is a small DC-DC regulator that fits on top of both regulator PCBs and can be used to generate an additional DC voltage from the main rail to power auxillary circuitry. Depending on the voltage differential and current draw, the AUXreg can use either a standard 78xx regulator or a switching type like the Traco TSR-1 or the Recom R78xx. The compact size means it can also be used as a “voltage thief” in many other places where you have a main DC supply but need a small extra DC voltage for a fan, a microcontroller or similar.

How big are the boards?

  • Regulator with heatsink (onboard-HS): 3.925″ x 20″ (app. 100×51 mm)
  • Regulator without heatsink (non-HS): 2.0″ x 2.0″ (app. 51×51 mm)
  • AUXreg: 0.4375″x2.0″ (app. 11x51mm)

What is the status of the boards?
The onboard-HS board is in v1.1. I built v1.0 and made some small adjustments subsequently, including moving the regulator footprint a little forward because it was too close to the heat sink and also tweaked the silkscreen a bit.
The AUXreg and the non-HS regulator are both in v1.0. I have built the AUXreg and it seems to work well as-is. I haven’t built the non-HS regulator but it is electrically identical to the onboard version it should be fine.

Does it use any special/expensive/hard-to-find parts?
Not really. The only potential exception is if your application requires a switching regulator for the AUXreg board – they can be a bit expensive.

Anything else I need to know?

  • The output voltage on the main regulator can be variable within a certain interval. If R1 is 121R, R2 will set the minimum output voltage (use my spreadsheet to calculate) and using a 500R/1k trimpot for P1 will give app. a 5V/10V adjustment range on the output from the minimum voltage. Note that with R1 = 121R, then C3 should be at least 22uF.
  • For the small caps on the main regulator boards, I recommend types that are rated for a 105C operating temperature as these sit very close to the heat sink. A 105C rating will help improve the reliability and overall lifespan of the caps.
  • The on-board heat sink is a Fischer type SK68/50. It is possible to fit a 40mm fan to the slots on top for improved heat dissipation.
  • Mounting considerations: Mounting the regulator and the PCB to the SK68 heat sink requires a bit of manual support because the screws tend to “slip” sideways in the slots. Also, you’ll want to mount the C1 capacitor last as it obscures the access to the mounting screw for the regulator.
  • For the AUXreg: The cap values C1 and C2 should be 330nF and 100nF respectively (ceramic or film types) for an 78xx regulator. For a switching regulator normally only a small electrolytic is required at the C1 position, but please consult the datasheet for the specific regulator you are using to be sure.

Downloads:
Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.

Always read the manufacturer’s datasheets for regulators etc. to confirm component values are correct. Even for “generic” types there may be slight differences between each manufacturer’s recommendations.