Automating turnout direction

Hi Stan,

I was also interested in this circuit and I think I know what all the parts are, but I can't seem to find the 40014 (which I think is a CMOS schmitt trigger?) in a dip package. Jameco gives me a 74c14 (CD40106 replacement?) which is the closest I can find, but I think that's a TTL device? A couple of years ago I read article about CMOS and TTL devices. From that I decided the CMOS was what I should be using, however the reason for this has vanished from memory? Anyway, do you have a source for the 40014? Digi-key and Mouser only seem to have surface mount devices, that I can find.

I don't know that I will use it for my layout, but I like to try and make these circuit for fun and learning purposes. I know just enough to be dangerous, but with each circuit I learn a little more. I think a small portion of it is finally even starting to stick.

The 74C14 will work fine, it's a true CMOS device that accepts 3.0 to 15.0 supply voltages.  In many places it's listed as a drop-in replacement for the 40014.

rtr12 posted:

...Anyway, do you have a source for the 40014? Digi-key and Mouser only seem to have surface mount devices, that I can find.

If you want it right away, Digikey has them for 48 cents: CD40106BE

For small orders, they ship first class for around $3.

Thanks GRJ and Stan,

I didn't search Digi-Key for the 40106, only the 40014 and came up empty or only with the surface mount items. I wasn't sure they were the same thing so thanks for that info also. I might use Digi-key, but Stan's ebay items are hard to beat. I do use Digikey for a lot of stuff, I like them a lot, great place.

Stan,

I thought I had some 4013s, but I do not so I would be interested in the 5 volt items as well if you don't mind. The more the better and it is a learning experience. I will have to order some of the parts anyway so might as well get both types.

Thanks again.

SN74AC14N for 47 cents at Digikey

This is a 2V - 6V part.

Here's a side-by-side of the 5V and 12V versions.  The equivalent 5V digital IC chips are the 74HC74 (instead of 4013) and the 74HC14 (instead of 40014/40106).  The 74HC family of parts do not operate over the wide voltage range of the so-called 4000 family.  But the 74HC parts are much more widely available from what I can tell.  The 74AC family that GRJ mentions would also work in this application (so 74AC74 and 74AC14).

Also, the 4013 and 74HC74 are digital IC chips that include 2 flip-flops per package.  Only 1 is used in the circuit.  When using this type of chip it is good practice to connect unused inputs to one side of the power supply as illustrated.  The 40014/74HC14 IC chips can have their unused inputs disconnected - saves a bit of wiring.  Note that this additional wiring of the unused half of the flip-flop chips was not shown previously but this latest schematic includes this.

If using the 5V version of the circuit, the relay module should be of the 5V ilk.  Dozens of Asia eBay vendors sell (from what I can tell) similar/same relay module but they seem to be just over $1 with free-shipping.  Example:

Parts are ordered and schematics are saved.  

Thanks again GRJ and Stan, for all the electronics info.

@ADCX Rob posted:

It would be much easier to just use a 101-3 mechanical E-unit tripped by the last car hitting an insulated rail at the tail end of the wye.

Reviving this old thread because I’d like to do precisely what the OP was looking to do and Rob your solution seemed to be a quick and simple way to do the job.

I understand in theory using the mechanical e-unit for this job, but not the exact wiring for it.

How would I wire the e-unit to an 022 switch?  If I used a 3-position eunit, it would simply take a turn not flip flopping correct?

@JD2035RR posted:

How would I wire the e-unit to an 022 switch?

@JD2035RR posted:

If I used a 3-position eunit, it would simply take a turn not flip flopping correct?

Yes, in a switch-back, it would go back the same way it came.