Insulated Rail Relay Based Sensor

I have put together a couple kits, they both work as expected.

I like the jumper option, simplifys some uses.

I have some questions

what is the correct jumper to use, what I have works but fits poorly

Is the Power on the board DC?   if so what voltage and total amps could be supplied.  I am wondering about stealing a little for other things

I understand that cap can be added to increase delay.  Is there a way that the relay could be made to come on when train comes into the section, but only stay on for a set duration?  Say 500 milliseconds.   What I want to do is parrot a button push.

My wife has a dept 56 dancing house, to get it to dance you push a button.  It would be cool if it started as a train went by.  So I only need to click the relay then let go.

Otherwise these are very nice.  Assembly was well documented and straight forward.

thanks everyone

Opps one more question

I soldered with rosin core solder, should I clean the board?  If so how should I do it

Questions... questions... questions...

BWRR posted:

I have some questions

what is the correct jumper to use, what I have works but fits poorly

A standard .1" .025 square post jumper is what the posts are sized for.

Is the Power on the board DC?   if so what voltage and total amps could be supplied.  I am wondering about stealing a little for other things

The regulator is 12 volts.  Note that the filter cap is really sized for the job, if you wanted any significant power (more than a few ma), you'd probably want to add a capacitor at J2.  If you intend to draw more than about 20-30 MA, you'd also probably need a heatsink on the regulator.

I understand that cap can be added to increase delay.  Is there a way that the relay could be made to come on when train comes into the section, but only stay on for a set duration?  Say 500 milliseconds.   What I want to do is parrot a button push.

Not with the present design, this was really intended as a signal driver for the insulated track.

...

 Opps one more question

I soldered with rosin core solder, should I clean the board?  If so how should I do it

I use 91% or 99% Isopropyl Alcohol for my board cleaning.  I use an old toothbrush to do the cleaning.

gunrunnerjohn posted:

Questions... questions... questions...

BWRR posted:

I have some questions

what is the correct jumper to use, what I have works but fits poorly

A standard .1" .025 square post jumper is what the posts are sized for.

Is the Power on the board DC?   if so what voltage and total amps could be supplied.  I am wondering about stealing a little for other things

The regulator is 12 volts.  Note that the filter cap is really sized for the job, if you wanted any significant power (more than a few ma), you'd probably want to add a capacitor at J2.  If you intend to draw more than about 20-30 MA, you'd also probably need a heatsink on the regulator.

I understand that cap can be added to increase delay.  Is there a way that the relay could be made to come on when train comes into the section, but only stay on for a set duration?  Say 500 milliseconds.   What I want to do is parrot a button push.

Not with the present design, this was really intended as a signal driver for the insulated track.

...

 Opps one more question

I soldered with rosin core solder, should I clean the board?  If so how should I do it

I use 91% or 99% Isopropyl Alcohol for my board cleaning.  I use an old toothbrush to do the cleaning.

 

Indeed Master GRJ, I am a Padawan full of questions.  I am certain that at times it gets old, I truly appreciate your willingness to answer them.

Jumper
Got it, struggled trying to find them, almost replied asking for more help.  Fell into calling it a "shunt" bingo more than I can even choose from

Power
Hmm sounds like a bad idea then, especially if it starts messing up the whole cap thing.  What I was thinking is using the PS on the board to run a couple of LED's, in a target signal for instance.  That way add this board to the base and I would have it all.  Perhaps it is better to just do it as two different boards.

Button Push
Unfortunate for this application, but I understand

Cleaning
That is what I was thinking of doing, this confirms it.

Speaking of cleaning.  I am using rosin core SnPb, should I always be cleaning joints or just when it is a mess like the back of a board.  When I join wires I have not been cleaning the joint.

Thank you very much for the help

I don't think a couple of LED's will upset the board P/S that much.  I was thinking more along the lines of more power usage.  Of course, it's almost as easy to run the LED's off the AC, you just add a diode to protect against reverse polarity, the current limiting resistor, and the LED.

I also use Rosin core, no need to clean simple wire splices, I don't clean those either.  I clean the circuit boards as it's a bit more obvious, but they'd work fine without cleaning.

OK, That is what I was thinking as well.  A splice is not that messy.  After doing a whole board there is a surprising amount of rosin on the board, making it sticky so I figured I would clean that.  Thinking that got me to wondering if there was a long term corrosion problem or something with leaving it, hence my question.

Just a diode and resistor, you do not use a rectifier?

As for the button push, when I dig out the christmas village I will look more carefully at the button.  At that point I will post a question to see what can be done.

Thanks a bunch BTW
I am really enjoying learning about all of this. 

A diode is a rectifier.

There are a host of cheap eBay modules that would connect to this sensor and give you a brief button push.  Stan0004 is a master of finding these on eBay, he seems to be able to find a module to do about anything.

Wow, Thanks Stan, my first gold star and *with distinction too!!! Been working on that for years. Also, I was unable to get my hat on this morning after reading this, way too tight!!

I get the extra relay part. I was thinking maybe the coil resistance had something to do with it, but I hadn't thought about the extra work for the cap figuring in there. I might fiddle around with the extra cap today? If I discover anything I will report back. Some of this sticks each time and I am going to really be dangerous one of these days. This stuff used to stick a lot faster when I was a lot younger.

I really do appreciate you and GRJ and others here taking time to explain all this stuff to us less knowledgeable.  

To all, as a side note, for jumpers I used one from a PC. I have been fiddling with those since the early '80s and each time I discard a board or add-on card I save all the jumpers, screws, etc. I have a bin full and the PC jumpers fit perfectly on these type of pins.

RTR12
Good for you!!!!  Getting a star from this group is truly high praise, I am a little jealous.

I have the same little box of jumpers from old computer boards and networking boards.  None really fit very well which is why I asked.  They work but did not feel "solid"

mike g. posted:

OK RTR, your starting to scare me, your reaching the area of Stan the man and GRJ! Next thing you know everyone is going to be running to you for help and answers! But that's ok cause I have had the great experience of asking you 3 and a lot of others for help. So I can say I asked for help before you got famous!

Great work there!

Thanks Mike,

But I wouldn't have known to do that if not for Stan's directions above. If everyone runs to me for help they may be in big trouble! You should stick with GRJ, Stan and some of the others here for good solid info. I am only just approaching the 'knowing enough to be dangerous stage'. Keep following those folks and you will learn a lot. May take a while, but it starts to stick after a while. 

I certainly do appreciate your kind comments though, and I thank you. Now my hat is really tight, my cheeks are starting to puff out and my eyes are bulging!

BWRR posted:

RTR12
Good for you!!!!  Getting a star from this group is truly high praise, I am a little jealous.

I have the same little box of jumpers from old computer boards and networking boards.  None really fit very well which is why I asked.  They work but did not feel "solid"

Maybe they are not all the same?? Sometimes the little metal contacts fall out of them or are missing too. I have seen that before.

And thank you for your kind comments too!!  I can't take the pressure build up, I'm off to the store for a much larger hat!! And a frame for my star!! 

rtr12 posted:

Now my hat is really tight, my cheeks are starting to puff out and my eyes are bulging!

Sounds like an allergy, get away from the electronics!

For the 1/2 sec pushbutton, I'd try a so-called "Delay OFF" 12V relay module.  The idea is you apply 12V to the module, this immediately closes its relay for some settable time, then the relay opens and remains open as long as 12V is applied.  Obviously, when 12V removed, the relay stays opens as there's no power to close the relay.  For example, Ebay # 132102329553 though there are dozens of sellers of the identical item. 

So this relay module would go where the plain 12V relay module went in rtr12's photo.  In this case the module has a screw-driver adjustable delay of 0 to 10 sec.   It's also on Amazon for a bit more.  Or use the search terms "Delay off 12V relay module" and you'll find additional options.

I see this module labels the 3-relay outputs CB COM CK instead of NC COM NO as labeled on the ITSD.  For the push-button application you want the two terminals COM and CK going to the push-button.

Bear in mind I don't have this specific Delay module but I believe it will do the trick.

Like I say, Stan is the master of finding the correct eBay module for the task!

Indeed GRJ,  when it comes to Ebay search Fu, Stan is indeed the man!!!!

So what is going on here is the relay on the sensor board is being removed and essentially replaced with the new board.  So the sensor board is supplying the power and control for the board, as if it was the relay.

I think I will buy one and give it a try.

Stan seems to always have the "magic" search term to come up with the exact solution.  Either he spends a lot of time looking, or he's just smarter than I am when it comes to eBay searches!

But, John, you are unchallengeable when it comes to finding something in the Figikey on-line catalog.

Received your sensor kit yesterday.  You package your products very nicely John.

Thanks, I'm glad it was received well.

I do spend a lot more time at the Digikey site than on eBay, so I do know my way around there.

I am horrible at that.  My ability to successfully permute terms to get useful hits is laughably poor, it seems as if pretty much everything I type in yields some sort of porn.  Fun to be sure, but often not quite what I was looking for.

Funny example:
At work (so there are PORN police)
Looking for a 20A power cord, standard plug on one end, lugs on the other.  Similar to what is used to hook up a dryer.  I have always called that piece of kit a "pigtail"  So I typed in 20A pigtail, and promptly clicked the first hit in the list.  While the young woman wearing only pigtails was pleasant to look at, she was not exactly what I needed.   The Porn police were not happy, not my most pleasant day to be sure.  

Then we have people like Stan, that can reach into the interweb and find all sorts of things.

I have learned that it is best to use ones resources!!

Thanks a bunch guys, I have ordered the board, it says it will be a couple of weeks getting here.
I will report back when I get it wired up

They must know your search history!

I just did a Google search on "20A pigtail", the first entry...  http://www.conntek.com/products.asp?id=193

The rest of the search screen...

Why can't I get search results like you do?  

I thought maybe I was missing something, so I looked in the images for the search... no dice, still just electrical stuff.

Just had to try it.......

Ya, I omitted a little.  I dont remember the exact search anymore.
I had added something to try and get the lugs (which I dont remember)
It was about 7 yrs ago now.  It was all the laugh in the department.
Not only did I get called down to the Principles office over it, but of course everyone in the department had to try it. So we caused quite a rukus until they broke our fun and blocked the actual address.

At the time my then teenage daughter had a game she played where she would read what I was going to put in as the search term before I hit return.  She would then 'bet' how far down the first porn hit would be.

It does not seem to happen to me as often now, I must be modifying my behavior.

above I went to digikey and typed in standard .1" .025 square post jumper

as you suggested, I got "We weren't able to find any results based on your search entry."
I thought, oh boy here we go.....

But I did finally stumble to jumper, but only with dumb luck

stan2004 posted:

For the 1/2 sec pushbutton, I'd try a so-called "Delay OFF" 12V relay module.  The idea is you apply 12V to the module, this immediately closes its relay for some settable time, then the relay opens and remains open as long as 12V is applied.  Obviously, when 12V removed, the relay stays opens as there's no power to close the relay.  For example, Ebay # 132102329553 though there are dozens of sellers of the identical item. 

So this relay module would go where the plain 12V relay module went in rtr12's photo.  In this case the module has a screw-driver adjustable delay of 0 to 10 sec.   It's also on Amazon for a bit more.  Or use the search terms "Delay off 12V relay module" and you'll find additional options.

I see this module labels the 3-relay outputs CB COM CK instead of NC COM NO as labeled on the ITSD.  For the push-button application you want the two terminals COM and CK going to the push-button.

Bear in mind I don't have this specific Delay module but I believe it will do the trick.

Here's one with a longer delay...

http://www.ebay.com/itm/0-60-S...c:g:cwYAAOSw8gVX6m6v

and less $$ to boot.

To late I have already ordered 132102329553, I am sure10s max will be fine for what I want to do.
The board has shipped, delivery is in a couple weeks.
I'll rig it up and report back when I have it

BWRR posted:

and less $$ to boot.

To late I have already ordered 132102329553, I am sure10s max will be fine for what I want to do.
The board has shipped, delivery is in a couple weeks.
I'll rig it up and report back when I have it

You could tack another electrolytic on that one if you needed more time.

gunrunnerjohn posted:

rtr12 posted:

Now my hat is really tight, my cheeks are starting to puff out and my eyes are bulging!

Sounds like an allergy, get away from the electronics!

I got an 8+ hat and it's still a little snug, but the puffing and bulging has gone down.  

It could be the flux fumes Stan was talking about, but it feels more like an addiction...I must get to ebay to order more stuff!! 

gunrunnerjohn posted:

Is the Power on the board DC?   if so what voltage and total amps could be supplied.  I am wondering about stealing a little for other things

The regulator is 12 volts.  Note that the filter cap is really sized for the job, if you wanted any significant power (more than a few ma), you'd probably want to add a capacitor at J2.  If you intend to draw more than about 20-30 MA, you'd also probably need a heatsink on the regulator.

What's the current rating for the choke?  It seems like that would be the major limiting factor to me.  

JGL

The choke is a 1/2W choke.  It's actual measured resistance is .45 ohms.  Let's say I'd dissipate 1/4W to be safe, that's still .7 amps.  I don't think the choke is a limiting factor.   The regulator would be overheated long before you get to .7 amps unless it has a pretty substantial heatsink.  With a 1/2 amp load, you need at about 1000uf filter cap to insure regulation with 18 volts input.  If the input voltage was lower, you'd need more filter capacitance.  With 1/2A output from the TO220 regulator, you also need a fairly hefty heatsink.

I admit that inductors are not something I'm very good with, but it seems to me that if you were drawing 700mA from a 7812, assuming a perfect world with no loss inside the regulator, then that would draw at least 8.4 watts.  That seems like it would burn up a 1/2 watt rated part pretty quickly.  Linear regulators are not perfect, however and they draw much more power than they supply, especially with input voltages much higher then their output.  I'd be surprised to see much more than 30mA on the output without drawing more than half a Watt through the choke.  

JGL

For DC or low-frequency (60 Hz), the power dissipation in an inductor is I^2 x R just as it would be for a resistor.  As GRJ says, the inductor's resistance is 0.45 ohms.  So if current is 0.7A, power is 0.7A x 0.7A x 0.45 Ohms = 0.22 Watts.

An ideal inductor has 0 resistance (and hence dissipates 0 power) so in the example given in addition to stealing 0.22 Watts from the output, the real-world inductor drops the voltage going into the regulator by  V = I x R or 0.3 Volts (0.7A x 0.45 Ohms).

Stan beat me to it.

Actually I'm more confused than ever as I've been unable to actually find a choke rated in watts.  They are all rated on max current, and that is a through-current figure as best as I can tell.  It seems like what you guys are saying is that it doesn't matter how much current you draw through the choke, only how much it wastes.  Inductors are black magic as far as I can tell.  

JGL

You're probably right, I bought them on eBay and they were rated 1/2W.  I computed the current at around 700ma and decided it was sufficient for my needs, probably times ten.

Here's a lower rated one on Digikey, 560ma and 740mOhm resistance. The B78108S1223K is smaller in physical size than my choke, using it's specifications, I come up with a power dissipation of .23 watts.  Given the size of my part, the 1/2W rating makes sense to me.  I put one on the bench and cranked up my bench supply to .7A. current limit, the part was dropping about .55 volts and the temperature went from 21C to 38C in three or four minutes.  It seems it easily handles the .7 amps without breaking a sweat.

However, there's no magic here, consider the choke as a low value resistor as far as 60hz is concerned, it's just dissipating a little bit of current.  A 1/2 ohm resistor would do the same in the circuit, and probably get about the same temperature.

The "magic" of the choke is at RF frequencies, it has a much higher reactance.  For 22uh at DCS frequencies, that's 452 ohms, hence my use of it to block the 3.27mhz DCS signal.  At 60hz, it's reactance is 0.0083 ohms, in other words, it's purely the DC resistance of the windings that determine it's characteristics.

stan2004 posted:

For the 1/2 sec pushbutton, I'd try a so-called "Delay OFF" 12V relay module.  The idea is you apply 12V to the module, this immediately closes its relay for some settable time, then the relay opens and remains open as long as 12V is applied.  Obviously, when 12V removed, the relay stays opens as there's no power to close the relay.  For example, Ebay # 132102329553 though there are dozens of sellers of the identical item. 

So this relay module would go where the plain 12V relay module went in rtr12's photo.  In this case the module has a screw-driver adjustable delay of 0 to 10 sec.   It's also on Amazon for a bit more.  Or use the search terms "Delay off 12V relay module" and you'll find additional options.

I see this module labels the 3-relay outputs CB COM CK instead of NC COM NO as labeled on the ITSD.  For the push-button application you want the two terminals COM and CK going to the push-button.

Bear in mind I don't have this specific Delay module but I believe it will do the trick.

When I get the delay relay board I will be doing the same thing as RTR12, not populating the relay on the sensor board and jumping to the delay board from the pads for the relay.  Correct?

Correct.  Note that the two interconnecting wires carry DC voltage so polarity is important.  RTR12 makes this clear with his use of the Red wire for DC+ and Black wire for DC-.  On the ITSD side they go exactly as he shows.  The relay board presumably will be as pictured, but in any event the white label "VCC" gets positive or DC+ (Red).

Hmm, I am guessing that depopulating the already installed relay is going to be a pain.

I will check with GRJ to see if he has anymore of the kits

Since you've already installed the relay, I suggest you simply leave it in place and attach the red and black wires under the board to the same two pads.  Your application is somewhat unique in that the external relay triggers/closes for at most 1/2 sec.  This is materially different than having both relays closing for many seconds or indefinitely if the train stops on the insulated rail section.

Just installed one of these sensors. They work great! Thanks Gunrunner !

Fred

I love success stories, thanks for the feedback Fred.

Would a 8A rated relay work ok for postwar block power switching?

Depends on what you're switching.  For most locomotives it certainly should.  For post-war, you probably won't be switching multiple locomotives on the same track, so I don't see it being a problem.

John, What is the description, specification or part number for a three pin header & connector that can be used for the second set of contacts on the DPDT  relay on the signal driver board? Thanks,