1. I think I may have figured that out, it requires a little hand routing to make it work.
2. There's only two IC's, I had oriented them to facilitate routing, so I rotated one with no issues.
3. The 3362P is twice the price of the the 3306F I'm using.
4. With a heatsink, the 7805T does the trick. I just moved it to the edge of the board where it could easily accommodate a heatsink.
5. They're labeled on the back, not any room to put the labels on top.
OK, here's one with the relay overlay, the chips all turned one way,
@gunrunnerjohn posted:1. I think I may have figured that out, it requires a little hand routing to make it work.
2. There's only two IC's, I had oriented them to facilitate routing, so I rotated one with no issues.
3. The 3362P is twice the price of the the 3306F I'm using.
4. With a heatsink, the 7805T does the trick. I just moved it to the edge of the board where it could easily accommodate a heatsink.
5. They're labeled on the back, not any room to put the labels on top.
1. Now I'm a happy camper! 
2. And you chose wisely...that is, now the DIP ICs even align with the DIP bridge! 
3. Yes, but by my reckoning, the #1 failure mode on the 153IR occupancy detector is the open-frame trimpot. With some shopping around, the 3362P is reasonably priced (20 cents each) in small quantity like at lcsc.com:
Not asking for a modified schematic to show both parts in parallel or anything fancy! I figure it costs you nothing to add 2 vias or holes...if only to shut me up! 
4. Yup.
5. Yup.
May be optical illusion but is the left-to-right distance 0.1"/2.54mm"...looks like the added holes need to move right just a tad.
Yeah, the 3362P is 2.54mm grid whilst 3306F is 2.50mm grid but I'll take what I can get. 
@stan2004 posted:May be optical illusion but is the left-to-right distance 0.1"/2.54mm"...looks like the added holes need to move right just a tad.
Yeah, the 3362P is 2.54mm grid whilst 3306F is 2.50mm grid but I'll take what I can get.
Picky...picky...picky... Yep, I screwed up the measurement, shouldn't calculate displacements in my head. 
That extra hole for the 3362P pattern should be 0.1" to the right of the #1 & #3 pins according to the data sheet, in the picture above. That's what I tried and it works well. The body of the 3362P winds up slightly left of center relative to the 3306 when installed, but no big deal.
Rod
It's now .1" to the right, hopefully I measured correctly this time.
Hmmm, the 3362P bodies might cover most of the RANGE and DELAY silkscreenings as they now sit? OK, I know, picky!
Rod
@Rod Stewart posted:Hmmm, the 3362P bodies might cover most of the RANGE and DELAY silkscreenings as they now sit? OK, I know, picky!
You're getting as bad as Stan!
@gunrunnerjohn posted:You're getting as bad as Stan!
Haha I knew you would say that! Looks great though, very nice compact fully functional board.
I really like the way you were able to morph both relay patterns into the same board space. great idea. 
Rod
I couldn't quite overlay the relays completely, in order to get clearance between the leads the smaller one wouldn't quite fit in the footprint of the big one. I got close...
The first time I did this, the autorouter couldn't handle it, so I manually routed the relay contacts. I moved them several times slightly shifting things, and the last time the autorouter managed to do the complete route without help.
I also shifted the regulator over a bit to allow a little more room to install a heatsink. I normally just whack one out of aluminum sheet if I need it.
Did the train already leave the station?
6. With smaller relay, U4 7805 becomes tallest component. But when bending regulator, I think it hits C1.
@gunrunnerjohn posted:...
The bell is ringing and the conductor is checking his watch!
Yeah but the doors are still open...
Now what about C2? I get just over 20mm from edge of board to top of 7805 tab when bent over...
@gunrunnerjohn posted:I don't see a problem.
Uhh, how on earth did that pass DRC? Look at the added hole in the RANGE trimpot.
I don't know, I did run the DRC.
Separately, did you confirm clearance from bottom of J1 to U2. The J1 silkscreen outline looks a bit small for a "real" screw-terminal block. That looks like a smaller square-pin header outline?
I figured it out. It actually did pass the DRC, but it was wrong. I moved the two posts to reposition the other stuff and forgot to move the extra hole with them.
@stan2004 posted:Separately, did you confirm clearance from bottom of J1 to U2. The J1 silkscreen outline looks a bit small for a "real" screw-terminal block. That looks like a smaller square-pin header outline?
The two pin 3.5mm terminal blocks fit on both of the connector positions, I just checked them. I'm using 3.5mm Euro-style connector blocks.
I just started looking into block detection (beyond the isolated rail) and ran into this thread. I stand in the presence of giants! Thank you all for your hard work and dedication to the hobby!
Hi Dennis, hope you are well. These detectors really do work very well. Not sure how many others have them in operation (other than the OP), but I have two working on the layout now, and love them. Several more are in the planning stage. And this got me back into 3D printing in a big way.
I plan to put the .stl files for the cabinets and bases in the 3D repository, but not sure what category they ought to go into. Can you advise? 
Rod
@gunrunnerjohn posted:The two pin 3.5mm terminal blocks fit on both of the connector positions, I just checked them. ....
Got it. I guess the 3D photo would have showed the clearance; it's just that in an earlier 3D photo the terminal block hangs over the end of the board such that the silkscreen does not actually match the footprint.
That said, it then seems you could fit top-of-board silkscreen lettering of NO C NC between the relay outlines and J2?
Rod, Beautiful work... and, thank you, for your generosity! If you can remember how to login... you have your own folder ...drop it in there. If you can't remember you can just email it to me and I'll take it from there. In either case I have to place it in the catalog anyway and bump (update) the thread so folks know it's available. Hmm... category .... I suppose Signals & Signs.
@stan2004 posted:Got it. I guess the 3D photo would have showed the clearance; it's just that in an earlier 3D photo the terminal block hangs over the end of the board such that the silkscreen does not actually match the footprint.
That said, it then seems you could fit top-of-board silkscreen lettering of NO C NC between the relay outlines and J2?
I could put it there, but it would be covered up by the terminal block, however I stuck them in. They're visible with that terminal strip model. I don't have a 3D model for the euro-style strips I use, they would cover the labels. The terminals I use come to the edge of the board, but don't hang over.
I also show it with your preferred small relay.
I'm a little late to this party. But how about this:
This uses the switching regulator from the EEU to power the relay to keep dissipation down if the train stops in front of the sensor. It should work from 8V to 20V AC.
Is that one all programmed and ready to work? I'll be glad to make a PCB for it.
Why the separate 5V regulator for the processor?
The switching regulator code exists. The sensor I/O would have to be added, but that is really simple. I do my own PCBs, and could have this ready in kit form within a few weeks. The only issue is availability of the PIC. I have some stock now, but they are now on backorder into August.
Oh, on the separate regulator... The switching regulator only turns on to close the relay. That is the same concept I used in the EEU described in OGR issue 305.
The PIC is "in the loop" stepping down the DC and hence needs a 5V reference voltage which is supplied by the 78L05. The neat thing is once the relay is closed, the PIC can step down the relay coil power to a fraction of the power to initially close the relay...this for the case of train stopping in front of sensor forever.
Since the relay is rated continuous duty, and the power dissipation in the switcher should be minimal, I don't see the burning need to reduce the coil current, but maybe that's just me.
The switching regulator controls the relay. While it is certainly possible to save even more power by reducing coil current after the relay is engaged, there was no intent to do that. The relay only consumes about a quarter watt when engaged.
It looks like the PCB can be about 1.6" x 2".
@SGJeff posted:It looks like the PCB can be about 1.6" x 2".
Goodness, I would hope it would be smaller than that! This one with a ton more components is 1.5" x 2"!
My first pass included a .1" border, but I squeezed to 1.8" wide with a .05" border. I assumed the sensor would be plugged vertically into the board, so there is free area on both sides of the sensor connector that eats up .2" in that dimension. Of course that can be eliminated with a 90 degree connector with the sensor hanging off the end as it would have to be with your layout. The relay, terminal block (.381 spacing), and trimmers dominate the board area. The sensor itself is 1.8" long, so that dictates the width.
Here is version the version 1.0 layout. Size is 1.8" wide by 1.5" high. There is room for mounting holes in the bottom corners. There may be some minor changes as I "apple polish" the routing. If there is sufficient interest I'll order a small batch of PCBs.
A connector can be used for J2 so the sensor can be plugged in or the sensor can be soldered directly to the PCB.
The general consensus is that the sensor would be remote with a short cable so you aren't stuck with the form-factor of the board and sensor sticking out.
In that case .2" could be shaved off the bottom of the board. But then the mounting holes would be lost too. Size shouldn't be an issue when mounting the sensor separately, so I'm going to leave it as it is. SMDs can be used if size is paramount, but that takes it out of the realm of being a kit.
Yep, I did a "quickie" with SMD, it was 1" by 1.5" in that case. This is just with parts on one side, even smaller if you use both sides.
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