Narrow Version of DIY 317 Voltage Regulator Board, with Build Files

Riki, you can't have common ground with a bridge rectifier. They must be isolated from eac other. Refer to the user notes up at the top. Common ground only works with half wave using a single diode.

Rod

Guys, addressing my ignorance, what are some uses/applications for the “common ground” option of these pcbs?  Why would I need to do this?  Thx Ted

Well for instance if you had a lighting circuit that used the engine or car frame as return, and you were using track power to feed the vreg module. This is a common ground, and half wave would be needed.

Rod

Using a diode inline with AC ground Will that work? To separate grounds?

NO!  You're confusing separating the grounds with combining the grounds.

 Thanks John. Hmmm. Ok...half wave it is.

With the boards. R1 holes could be a little larger. Pretty tight. Have to use pliers to pull thru.

TedW posted:

Guys, addressing my ignorance, what are some uses/applications for the “common ground” option of these pcbs?  Why would I need to do this?  Thx Ted

photo hi-jacked and modified from previous OGR thread

In addition to rolling-stock, it could be used track-side if you use/need insulated-rail relays for signals, crossing gates, etc.  It's just that off-the-shelf relays run about $10 each (plus shipping).  But using Rod's board configured for half-wave common-ground with 12V DC output, you could use transformer AC Accessory voltage (e.g., 16V AC) with a 1, 2 or 4 channel 12V DC relay module from eBay free shipping from Asia.  The relay modules are less than $1 per relay so you could rack up some serious $avings!

TedW posted:

Guys, addressing my ignorance, what are some uses/applications for the “common ground” option of these pcbs?  Why would I need to do this?  Thx Ted

If you do anything with TMCC or early Legacy, many of the signals and lights are returned to frame ground.  So, most of the stuff I build either uses half-wave power or has an option to jumper for half-wave power so I can use it in those situations.

Hi all. Just got finished building one of these narrow vreg boards, and I am happy to say it works exactly the same as the more rectangular original version. This build is the full enchilada with 22uH choke, bridge rectifier, 5K trim pot, 1000 uF filter cap. Output range is 1.4 vdc to 25.5 vdc; using a 19 vac brick for AC supply.

All is well as far as I can see. 

Rod

I'm 2 out of 4. Half wave. 

Replaced 317. On 2 .  No change one. Still not regulated .

The other no output.

Building 2 more. See how that goes.

Rod the ones I have r1 holes are to small.

2 more tested good. .

But. R1 holes are a pita...i don't have a drill small enough.

I did see some small drills on Amazon few months ago. Think they were for pc boards.

I also changed where I hook up. 

Neg is across from diode. Leaves the end. Of board with only wires on each end.

Dc+

And AC in.

Riki, sorry to hear you are having problems. The 2 that are not working must have something different in your component wiring, compared to the others that are working.

For the 2 that are working, are you getting the desired output voltages? What are your R1 and R2 values?

Most modern 1/8-1/4 watt resistors have small leads and will fit those R1 hole sizes. Older 1/4 watt and larger 1/2 watt resistors use slightly heavier leads and might be tight. My good friend rtr12 reported those holes being a bit tight on a board he built, but said he eventually got them through OK. I personally have not had this problem. 

One idea might be to cut the resistor leads short and bend them so that you can surface solder them on the top of the board. Or cut one short and one slightly longer and mount the resistor vertically as you had on one board. Tin the pads and leads first. No risk to the board doing it this way. 

Rod

Yes. Voltage is what I thought it should be.

Easier to solder with leads in the hole.

Using 1/4 watt resistors.

Is there anyway to check a 317 reg.  If it works or not?

But. I did replace 2. And they didn't regulate . so ..hmmm. Bad board.s. 

I 5 5 good ones.

3 that don't hold fixed voltage.

It's so unlikely that you'd run across multiple LM317 regulators that are bad that I'm having trouble coming up with enough zeros after the decimal point to express it.   I'd be looking elsewhere for the problem.

Thanks John.

Resistors check ok. Diode  checks ok. Capacitor ?. 

How about a picture of what you have built?  This is such a simple circuit I'm having a bit of trouble with it not working.  Let's see the front and the back of the board.

 I seriously doubt there is a electronic problem more then likely you put a diode or capacitor in backwards! as was said this is a really basic circuit that should not be giving you issues unless you wired the components in backwards or wrong! I noticed one board that you put a large diode in that looks  like  to me that you had the one end of the diode shorting against a lead real close by!

!!

Alan

So that no heat is used on 317. I made a 3 pin socket.

Bojack..anyone used those.?. 

Haven't tested these yet. Later. Today.