3 aspect model RR signalling help plse

[Raiway Pete]

Ok guys,

I'm still here. Had a little problem. Thought my dcc power supply had blown up (before making the circuit). So ordered a new one only to find the 2pin adapter for the power supply didn't have a fuse in it!. Now I got 2 power supplies

V funny MrDeb, no smoke as yet. Still sorting getting a test track working. Think it's ok now.

Read both your comments. Now I got 2 questions about them.

1. Pete, if I use NPN power transistors do they get wired up the same as the PNP ones or do I have to change something.

2. MrDeb, are the diodes in the other detector circuit also powr diodes? I got four of them. Is that right?

Now you're both worrying me. Hope I got the right bits!

4 x 1N5402 diodes
2 x TIP31C
2 x Photocoupler thingies
1 x 0.1uF poly cap

will try 2 1N5402's with capacitor and the 2 TIP31C's

Then try 4 1N5402's as rectifier with 2 2N3904 transistors, or does the other circuit also need power transistors?

Angie,

No power diodes are required with the power transitrors. If you are using power transistors they handle all the current. Build the plain ole' circuit I sent you with two power transistors, a 3.9K resistor and a red LED. I would put a 0.1 Micro farad capacitor across the double base/emitters of the transistors, but for you this may not be necessary. The reason I waffle about that is the fact you are using 12 volts instead of (my) 18.

As for the wiring. You are using NPN power transistors therefore the collector resistor must be connected to your +12 volt output pin(?) and the negative (0 volts) to the common ground.

If you decide to use signal transistors then build the circuit using only two power diodes back to back across the emitter/base connection (not four ---yet).

Post your (interim) results.

Good Luck

Pete

PS look in your mail box.

 

[MrDEB]

the small signal transistors/ diode combo is cheaper than using the power transistors.
see an earlier post about cost.
they both work the same basically.
glad to hear your still here. For a miniute there I though you were out on a date with Tiger Woods---lol
assuming your female, Angie born in November 1999?? WAIT can't be right, that would make you 10 years old??
Fill us in Angie, inquiring minds want to know (just curious)
and no I am not a dirty old man, well two outta 3 agn't bad (59 and just got done working on a wood tabernacle for a guy for Christmas, so I am covered with fine sawdust.

 

[MrDEB]

Now RailWay Pete, thats the guy to watch out for.
lets see, born before the rail road was invented or perhaps he was in Utah when they pounded in that gold spike (the one he has in hie rail road room is just painted with gold paint but don't tell him that. coarse he can't hear very good anyway


LOL

 

[Raiway Pete]

Now RailWay Pete, thats the guy to watch out for.
lets see, born before the rail road was invented or perhaps he was in Utah when they pounded in that gold spike (the one he has in hie rail road room is just painted with gold paint but don't tell him that. coarse he can't hear very good anyway


LOL

I'm not saying I'm old. Oh no no no! But I served in Her majesty's Royal Air Force when Pontius was a pilate. aserved in the Middle East for three years then in the UK. Got out, went to Germany for five years and toured Europe for my job. Visited North Africa too. Got a transfer to The U.S.A. and am still permanently there. Right now I am on a self imposed assignment (teaching) in Slovakia. I have to quit that pretty soon as I'm pushing the big 7 Oh!

How's the building going.

One other point about the Twin-T. When we are talking about cost the difference is pennies. The advantages of using Power transistor far outway the extra cost. All the current goes through the transistors and that makes that option more sensitive. My next step is to solve the problem of Twin-T detection without power applied to the track.

Regards to both o' yer

Pete

 

[MrDEB]

How is Pontius these days? still a pilate.
What air force was or is he in??


LOL

 

[angie1199]

LOL, see I told you I get confused.

Ok, so the circuit MrDeb and I got the schematic working for has 4 power diodes with 2n3904 signal transistors.

Pete's Twin-T circuit uses power transistors, no diodes, but may require a capacitor.

Or if I want to use signal transistors with the twin t then I use two power diodes.

As for the wiring. You are using NPN power transistors therefore the collector resistor must be connected to your +12 volt output pin(?) and the negative (0 volts) to the common ground.

Direct? So how does that link to https://www.electro-tech-online.com/attachments/simplest-twin-t-pdf.36275/

A schematic would be good just about now

 

[angie1199]

glad to hear your still here. For a miniute there I though you were out on a date with Tiger Woods---lol
assuming your female, Angie born in November 1999?? WAIT can't be right, that would make you 10 years old??
Fill us in Angie, inquiring minds want to know (just curious)

Bit older than 10, my grandfather gave my father a model railway in about 1967, I loved it then, still do. Always wanted a decent sized model but didn't have the space. Now I do so it's my 'getting older' project.

No date with Tiger, got a guy who wouldn't do that to me

 

[Raiway Pete]

How is Pontius these days? still a pilate.
What air force was or is he in??


LOL

Hi Mrdeb,

I was in the british Royal Air Force. Many, many years ago. That was a time when you were just a glint in your father's eye.

 

[MrDEB]

You need a schematic?
I thought you had one already?
Will have to draw you one up. need to locate Tina schematic first then draw one out.
I think about 3 pages back I posted a schematic and the Twin T on one pc board.

 

[angie1199]

I think about 3 pages back I posted a schematic and the Twin T on one pc board.

You mean this one? https://www.electro-tech-online.com/attachments/2diodes-png.36235/

This is the one with two diodes. The only one without diodes, the one with two power transistors, is with PNP transistors, not NPN : https://www.electro-tech-online.com/attachments/simplest-twin-t-pdf.36275/

So do I just replace the transistors with NPN or do I need to make other changes?

Told you I get confused

 

[MrDEB]

schematic and pc board

Here is schematic for one detector and signaling circuit combined.
Pretty sure its right but double check.

 

[angie1199]

Ok, this one doesn't work

https://www.electro-tech-online.com/attachments/notworking-jpg.36250/

 

[Raiway Pete]

You mean this one? https://www.electro-tech-online.com/attachments/2diodes-png.36235/

This is the one with two diodes. The only one without diodes, the one with two power transistors, is with PNP transistors, not NPN : https://www.electro-tech-online.com/attachments/simplest-twin-t-pdf.36275/

So do I just replace the transistors with NPN or do I need to make other changes?

Told you I get confused

Hello Angie,

I suggest you use the one I sent you. The PC board and the component layout is all there. I sent you an updated version with component values inserted. Forget about signal transistors and diodes for now. We will address that later after you decide how many units you want to build. Then when we do a cost/performance analysis. The TIP31C transistor unit is more sensitive than the signal transistor with shunting diodes version. I suggest you build the TIP31C version first. Then you will have enough confidence to try the signal transistor version. Now your decision can based on performance versus cost. The difference is pennies anyway.

Pete

 

[angie1199]

This works perfectly. With 1 dry finger on track!!!!

https://www.electro-tech-online.com/attachments/working-jpg.36249/

 

[angie1199]

I suggest you use the one I sent you.

I'd love to try yours but it's showing PNP transistors despite the text saying TIP31C which is NPN.

I did already ask what changes to the schematic I'd have to make but got no answer

 

[Raiway Pete]

I'd love to try yours but it's showing PNP transistors despite the text saying TIP31C which is NPN.

I did already ask what changes to the schematic I'd have to make but got no answer

Angie,

i just forgot to change the little emitter arrows. Go ahead and build it with NPN TIP31Cs.

 

[angie1199]

Angie,

i just forgot to change the little emitter arrows. Go ahead and build it with NPN TIP31Cs.

I just got a comparison quote for 25 units. I know there will be at least 25 if not more units required. The more I build, the cheaper they become due to bulk order of components.

I think I'll be going with the one I already got working as the twin-t is twice the price due to the cost of the TIP31C's

 

[Raiway Pete]

This works perfectly. With 1 dry finger on track!!!!

https://www.electro-tech-online.com/attachments/working-jpg.36249/

Cool, but now take out two power diodes and try it. It should also work and it will be more confortable for the two signal transistors.

Attachments.

I took pictures of the Pc card I am using. Notice that I used two signal diodes with TWO power diodes across the PN junctions. There is one however where I used two power transistors without any shunting power diodes. The 'detector only' card is now obsolete but it still indicates the Twin-T, a booster inverter and a debouncing relay driver. The delay is about half a second.

The simple-ABS signal has the diode matrix populated with the LED current limiting resistors and the four diodes used to contro them.

The development board is a prototype wherby I can move the diodes around to change the aspects. It control two 4 aspect signals and includes a flash unit that indicates a 'diversion clear' which has two yellows with the upper one flashing.

The dbl sig 5 aspect one is a finished 'production' card. It controls the entry to a station and drives 5 aspects. It drives four normal aspects and a warning flashing white for 'shunting in progress' . This allows a train driver to take his engine 50 meters past the flashing white for shunting purposes.

Note. This last card uses power transistors without any diodes. It is very sensitive but the reason I used them is that I'm running out of signal transistors and I had power transistors in stock. I was told by an expert that the Twin-T won't work with DCC. Hm! I guess he was an "ex spurt". Bill's
cryptic expression for "a has been drip under pressure" (I liked that).

 

[Raiway Pete]

I just got a comparison quote for 25 units. I know there will be at least 25 if not more units required. The more I build, the cheaper they become due to bulk order of components.

I think I'll be going with the one I already got working as the twin-t is twice the price due to the cost of the TIP31C's

OK but take out two power diodes. I don't have any experience with the Twin-T using 2N3904s. That drops the price by another 10p.

 

[angie1199]

Seems like a lot of components compared to my 8, 4 diodes, 2 transistors, 1 resistor and 1 optocoupler.

Now I need to work out the connection of the optocoupler instead of the led and then the pcb for a detector only circuit with 2 connections one side (dcc power) and 3 the other (12V, Gnd, Detect)