EETECH 00 mentioned the chip, but you might want to use the full part number to get the DIP version and not the surface Mount versions or you can't use the socket option. Looking at the data sheet, here is a snippet of that data sheet for reference.


If you order the part from a supplier, the correct part number to order is: TBD62003APG. The PG part is the DIP part shown above which you can insert in a socket. (Note the notch in the picture of the DIP version, top picture.) Pin 1 of the device is the pin closest in that view, the pin over the "D" in the "DIP16-P-300-2.54A". I was worried about including a pull down resistor but I don't think it will be needed, but if you have issues with the LED's changing state without operating a switch, it might be a good option? I was reading this thread and I'm glad EETECH00 understood all this I was lost for some time... I find it really interesting to just understand ABS signaling on the local UP main with just 14 lines, if I remember right... I hope the TS will post the final results once the system is complete.

 

EETECH 00 mentioned the chip, but you might want to use the full part number to get the DIP version and not the surface Mount versions or you cant use the socket option. Looking at the data sheet, here is a snippet of that data sheet for reference.
View attachment 230621

If you order the part from a supplier, the correct part number to order is: TBD62003APG. The PG part is the DIP part shown above which you can insert in a socket. I was worried about including a pull down resistor but I don't think it will be needed, but if you have issues with the LED's changing state without operating a switch, it might be a good option? I was reading this thread and I'm glad EETECH00 understood all this I was lost for some time... I find it really interesting to just understand ABS signaling on the local UP main with just 14 lines, if I remember right... I hope the TS will post the final results once the system is complete.

I’m sorry if I didn’t make things as clear as I see them in my head
I haven’t done any technical drawings or schematics since school 30 odd years ago
But everyone who has replied has been so helpful explains everything to a complete novice
I’m definitely gonna get myself a book or two on electronics and have a play about and il definitely post the completed project once I’ve done the track laying bit
I wanted to know if my idea was feasible and cheap enough before I started it

 

so the zig zag line r1 / r2 510 are the resistors ?

Yes. That is the symbol for a resistor. The value "510" (ohms) is shown below the symbol.

I’ve got the resistors already along with leds and some diodes

ok

 

Yes. That is the symbol for a resistor. The value "510" (ohms) is shown below the symbol.

ok

I think I’ve got 1k resistors does that sound right

 

I think I’ve got 1k resistors does that sound right

1K will work but the LED will be dimmer because there will be less current flowing thru the led.
Sometimes the choice of resistor value depends on the desired brightness and is a trade off of brightness verses damage to the LED.

 

I think I’ve got 1k resistors does that sound right

Maybe. I know model railroaders have a rule of thumb to use a 1K resistor for any LEDs. It works, but you may observe a difference in brightness that you don’t like.

Eetech’s recommendation of 510 ohm resistors will provide a brighter light. If the LEDs are mounted on a panel, 1K resistors are probably ok. If on the layout in a model signal mast under layout lighting, you might find them a bit dim.

 

1K will work but the LED will be dimmer.

Il order some chips and bases
And some 510 resistors
And have a play about with it

 

Maybe. I know model railroaders have a rule of thumb to use a 1K resistor for any LEDs. It works, but you may observe a difference in brightness that you don’t like.

Eetech’s recommendation of 510 ohm resistors will provide a brighter light. If the LEDs are mounted on a panel, 1K resistors are probably ok. If on the layout in a model signal mast under layout lighting, you might find them a bit dim.

I will have a go at just laying the plan out on a sheet of board and use blutack to keep things in place so I have some idea of it working before I mount it properly

 

Il order some chips and bases
And some 510 resistors
And have a play about with it

What software do you use for your diagrams I’m just scribbling stuff down on printer paper lol

 

I’m sorry if I didn’t make things as clear as I see them in my head
I haven’t done any technical drawings or schematics since school 30 odd years ago
But everyone who has replied has been so helpful explains everything to a complete novice
I’m definitely gonna get myself a book or two on electronics and have a play about and il definitely post the completed project once I’ve done the track laying bit
I wanted to know if my idea was feasible and cheap enough before I started it

For experimenting and testing simple designs I suggest you buy the following:

Breadboard

Jumper wires

Then you can "plug in" parts onto the breadboard, jumper the pin connections, connect power, and test your circuit.

 

For experimenting and testing simple designs I suggest you buy the following:

Breadboard
View attachment 230623
Jumper wires
View attachment 230625
Then you can "plug in" parts onto the breadboard, jumper the pin connections, connect power, and test your circuit.

Omg I haven’t used them since school
Il definitely have to get some of that

 

What software do you use for your diagrams I’m just scribbling stuff down on printer paper lol

I used MS Visio for the panel layout but that has steep learning curve. I don't recommend you use that yet.
I used LTspice for the circuit diagrams but don't recommend that for drawing schematics.
I've had years of experience with both these tools so its easy for me.

Maybe someone here can recommend drawing software...(?)

 

I used MS Visio for the panel layout but that has steep learning curve. I don't recommend you use that yet.
I used LTspice for the circuit diagrams but don't recommend that for drawing schematics.
I've had years of experience with both these tools so its easy for me.

Maybe someone here can recommend drawing software...(?)

I got a book on railway electronics but the only thing I’ve done in it on a previous layout was to use a diode to stop a train going off the end of a track as soon as it passes it and stays there until the train is reversed
But I’m really looking forward to this now
I’ve recently retired and have plenty of time on my hands and this will stop my wife finding me jobs to do as il be hiding in the garage

 

For a beginner drawing schematics, ExpressSCH is a good start. It will introduce you to the techniques used in more advanced tools. Or it’s easy to learn for beginning users. It used to be free; I haven’t checked lately.

 

For a beginner drawing schematics, ExpressSCH is a good start. It will introduce you to the techniques used in more advanced tools. Or it’s easy to learn for beginning users. It used to be free; I haven’t checked lately.

Il have a look for it

 

This is just a quick sketch
I will be using peco switches that attach to the point motor
They are on / on type switches
So the first feed will be 9v dc
The two outputs will power a green and red light at point one A and B
But the next switch will only be powered from the green light so latter points can’t be green unless the preceding one is also green
I have numbered the points 1-4 and gave each exit A-B where the signals will be

so say point 1 is set straight
A will be green and B will show red
Both signals at point 4 will take a feed for the red lights off of point 1 b as because that is red no train will move at point 4

now point 2 will take a feed from the green at point 1
Let’s say this point is set straight
A will show red and B will show green
Point 3 will take the feed from the green at point 2b to feed into the switch at 3
I know I might have to use some diodes in this setup

One thing I'd like to mention, based on my experience with a RR Control systems, is about RR control panel nomenclature .

Railroads usually use odd numbers for identifying switches/turnouts, and even numbers for signals. The signals are appended with an E or W (East or West), or, N or S (North or South) to further identify direction. There are exceptions but very rare.
For example, for a double crossover type interlocking, the switches would be labeled 1 and 3, while the signals are labeled 2E, 2W and 4E, 4W.

I realize, however, that this is a model railroad, and since you're the "Chief Signal Engineer", you can use whatever nomenclature you want.
Just sharing....

 

One thing I'd like to mention, based on my experience with a RR Control systems, is about RR control panel nomenclature .

Railroads usually use odd numbers for identifying switches/turnouts, and even numbers for signals. The signals are appended with an E or W (East or West), or, N or S (North or South) to further identify direction. There are exceptions but very rare.
For example, for a double crossover type interlocking, the switches would be labeled 1 and 3, while the signals are labeled 2E, 2W and 4E, 4W.

I realize, however, that this is a model railroad, and since you're the "Chief Signal Engineer", you can use whatever nomenclature you want.
Just sharing....

Model railroaders use a modified approach. Before the days of DCC, railroad blocks or sections were numbered sequentially. The block number corresponded to a physical DC section of tracks. Hence, the MRR term, block control. Blocks were assigned to different power sources - throttles - by a multi-position switch. A rotary switch in large or club layouts or often a DPDT or SPDT toggle on home layouts.

Turnouts and signals were assigned a sequential sub-identifier within each electrical block, such as 5-3. That is the 3rd turnout or signal within electrical block 5. Use of the odd/even differentiation was not common.


* SPDT switches were used in a wiring convention called common rail, where one rail of the track was a common ground. This required DPDT switches on blocks designated reversing blocks. Where the common rail ended up on the opposite side where the tracks are used to reverse train direction. This was a concept which boggled the minds of many a neophyte MRR.

 

Late to the party, just one thought (for now) -

In posts 45 and 49, 50% of the resistors can be eliminated. If I understand this thread correctly, each red/green LED pair is mutually exclusive. If true, then for each pair, there need be only one resistor between the +12 V and the two LED anodes.

ak

 

Late to the party, just one thought (for now) -

In posts 45 and 49, 50% of the resistors can be eliminated. If I understand this thread correctly, each red/green LED pair is mutually exclusive. If true, then for each pair, there need be only one resistor between the +12 V and the two LED anodes.

ak

That is true. Not sure if the circuit will stay that way yet, but your point is well taken.
Thanks.

 

Model railroaders use a modified approach. Before the days of DCC, railroad blocks or sections were numbered sequentially. The block number corresponded to a physical DC section of tracks. Hence, the MRR term, block control. Blocks were assigned to different power sources - throttles - by a multi-position switch. A rotary switch in large or club layouts or often a DPDT or SPDT toggle on home layouts.

Turnouts and signals were assigned a sequential sub-identifier within each electrical block, such as 5-3. That is the 3rd turnout or signal within electrical block 5. Use of the odd/even differentiation was not common.


* SPDT switches were used in a wiring convention called common rail, where one rail of the track was a common ground. This required DPDT switches on blocks designated reversing blocks. Where the common rail ended up on the opposite side where the tracks are used to reverse train direction. This was a concept which boggled the minds of many a neophyte MRR.

That's an interesting use of terms.
In the real RR world, the term "Block" has a different meaning, such as "signal block", meaning a track section with entry governed by signals. Or "Track Block", meaning a section of track that has been placed out of service for maintenance.

I guess I need to get used to the model RR terminology...