CPL signal automation?

[pedro]

Hoping to tap into the TRW brain trust here...


I am currently restoring a 1:1 scale US&S dwarf CPL signal. It's already in working condition, tested with an MRC power pack. Pretty simple 12V DC wiring, four different aspects possible. (Clear, approach, restricting and stop.) While the easy way to light this for display would be to put in a rotary switch and select the aspects manually, I'd like to explore the possibilty of coming up with a circuit that would automate the process and change the aspect every 2-3 minutes. I would also like to put in a transformer with an outdoor-rated, grounded plug. This is small enough to be mounted on my deck. There's plenty of room for components in the base enclosure.


Anyone have any ideas on how to do this? I plead ignorance in electronics of this nature, but am not afraid to follow a plan if someone knows of one!

[railnerd]

Should be possible to light this up and automate it with an Arduino and a set of discrete driving circuits.  Do you know what the current rating is for the bulbs?

-Dave

[peteski]

Pedro,
if I understand this correctly, you, there will be 4 pairs of bulbs (2 bulbs in parallel).  Bulbs 0 and 1, 450 and 460, 90 and 91, and 45 and 46.  And you like to light up each pair in sequence.

Since you are not electronically-inclined, you could simply buy a low voltage sequencer and a simple filtered DC power supply and that will do the job.

I did a quick Google search and I found what seems to be a suitable sequencer.
http://digitallighting.com/animationfolder/CF400%20LED%20PWM%20dimmers.htm
Then you would have to get a DC power supply which should not cost very much.  Hook up the power supply to the sequencer and the 4 pairs of bulbs to the sequencer outputs and you're done.
The only possible problem is that the sequence speed you want (once every couple of minutes)  is longer than the sequencer's maximum time. But I looked at the sequencer's manual and it looks liek you can call the manufacturer and request customized features, so longer sequence time period might be doable.

[pedro]

Thanks for the responses. Peteski, correct on the sequence. They light up in those pairs. The off the shelf sequencer looks good, but spendy. Will keep it in mind for sure. Is this overkill for incandescent bulbs? I see mention of LEDs in the descriptions. Was hoping there was some lower tech, lower cost solution. I'm not averse to rolling my own, just have no idea on circuit design.

The bulbs are 18W 10V.

[peteski]

Thanks for the responses. Peteski, correct on the sequence. They light up in those pairs. The off the shelf sequencer looks good, but spendy. Will keep it in mind for sure. Is this overkill for incandescent bulbs? I see mention of LEDs in the descriptions. Was hoping there was some lower tech, lower cost solution. I'm not averse to rolling my own, just have no idea on circuit design.

The bulbs are 18W 10V.

Then each bulb will require 1.8 Amps (or 3.6 Amps/pair).  That is a fairly heavy current.  That sequencer can handle 5 Amps per output, so it is safe to use since only one pair will be illuminated at any given time.  The sequencer mentions LEDs because it uses PWM (Pulse Width Modulation) for dimming, which is most compatible with LEDs (but perfectly usable for incandescent bulbs).

If you want to roll your own and you are handy with soldering electrical components, I could come up with a circuit which uses a 555 timer IC for clock pulses, a 4017 decade counter IC as the sequencer, 4 transistors to drive 4 relays to power the bulbs, 4 relays, and several miscellaneous resistors and capacitors. The most expensive part of the circuit would be the relays, but it will still be likely less than $30 for all the parts. You still need a 10V power supply (in that case we could run the bulbs from AC output of the transformer.  That would be a really basic circuit if you can assemble it. It is an old-school solution. Or you can go the microcontroller (Arduino) route and create the sequencer as a piece of code inside the Arduino. You still need the high-power section to drive the bulbs.

[pedro]

Thanks for the offer to help with a circuit! I like the sound of the old-school option, that’s exactly what I had in mind.  Nothing against the Arduino option, it’s certainly something to consider. I just have no experience with anything like that. Need to learn.

[peteski]

Give me few days to come up with the schematic and parts list.

[peteski]

Pedro, I've been thinking . . . 10V bulbs are a bit of a oddity in the general consumer world.  In use, they will eventually burn out and unless you can find replacements, you'll be stuck in the dark (so to speak).  Unless of course you know a reliable source for them.

Looking at the photos, these bulbs look like they use a standard bayonet type of a base like automotive bulbs.  If that is the case, this might be a good time to retrofit standard 12V automotive bulbs since they are easy to buy if needed.  If you decide to use the 12V automotive bulbs then I'll need to design the circuit using a different power transformer.  Let me know.

[Point353]

The off the shelf sequencer looks good, but spendy.  Was hoping there was some lower tech, lower cost solution.

What's your definition of "spendy" versus "lower cost"?

[pedro]

Pedro, I've been thinking . . . 10V bulbs are a bit of a oddity in the general consumer world.  In use, they will eventually burn out and unless you can find replacements, you'll be stuck in the dark (so to speak).  Unless of course you know a reliable source for them.

Looking at the photos, these bulbs look like they use a standard bayonet type of a base like automotive bulbs.  If that is the case, this might be a good time to retrofit standard 12V automotive bulbs since they are easy to buy if needed.  If you decide to use the 12V automotive bulbs then I'll need to design the circuit using a different power transformer.  Let me know.

Correct on both counts. The railroad bulbs can be had easily on eBay, about $6-7 each. They are extremely robust and bright. And yes, standard #93 automotive bulbs can be substituted. I guess I’d like to stick to the railroad bulbs, since I have a full set now and a ready supply available. I also have another signal to work on once this is complete that uses the same bulb.

Thank you for your willingness to work on this!

[pedro]

What's your definition of "spendy" versus "lower cost"?

I guess that’s pretty arbitrary. ~$30 in components vs $85 lighting module (without power supply) fits my budget a bit better. Time spent on it doesn’t factor in for me, that’s one thing I have plenty of!! YMMV.

[Point353]

I guess that’s pretty arbitrary. ~$30 in components vs $85 lighting module (without power supply) fits my budget a bit better. Time spent on it doesn’t factor in for me, that’s one thing I have plenty of!! YMMV.

Here's one possibility that's not $30, but not $85 either.

4-output sequential controller board: http://www.newark.com/cebek/28-22972/4-output-sequential-control-pre/dp/43W7655
http://www.farnell.com/datasheets/2364586.pdf

12V/4A power supply: http://www.newark.com/multicomp/mc141007/wall-mount-adaptor-30v-5a-50-4w/dp/96Y6617
http://www.farnell.com/datasheets/2290308.pdf

Rectifier diodes (3 needed in series to reduce 12V down to 10V for lamps) : http://www.newark.com/multicomp/p600g/rectifier-single-400v-6a-p600/dp/28AC1367
http://www.farnell.com/datasheets/2312442.pdf

About $55, plus an enclosure for the controller. 

[peteski]

@pedro
Pedro, here is a diagram and a parts list for your sequencer.



I like using Digikey or Mouser Electronics as my parts suppliers, but they don't seem to carry many of the now-older DIP-style integrated circuits. They pretty much only carry the Surface Mounted versions.  Those wouldn't work for you when using a breadboard. But I found the older chips at Jameco Electronics, so I included links to those parts.  Digikey has hundreds of breadboards - I picked one that I thought  would be suitable for this circuit.

I included individual prices (you have to calculate the total).  I  didn't include the power cord, power switch, fuse and fuse holder, or the enclosure (or shipping costs).

Digikey parts:
T1 - HM4760-ND  XFRMR 50VA CHAS MOUNT single primary, single center-tap secondary 10V 5A $17.31
RY1-RY4 - 255-2062-ND RELAY GEN PURPOSE SPST 10A 9V 40mA coil $1.58 ea
D1-D4 - 1N4003-TPMSCT-ND  DIODE GEN PURP 200V 1A DO41  $0.11
BR1 - 1655-1825-ND BRIDGE RECT 1PHASE 600V 1A DB-M $0.47
Q1-Q4 - BC337-40-APMSCT-ND TRANS NPN 45V 0.8A TO-92 $0.47

IC1 - 497-1448-5-ND IC REG LINEAR 9V 1.5A TO220AB $0.45
IC2 - 296-1857-5-ND IC OSC SINGLE TIMER 2.1MHZ 8-DIP $0.84
IC3 - 296-2037-5-ND IC 10-OUT DECADE COUNTER 16-DIP $0.53

VR1 - 262UR105B-ND TRIMMER 1M OHM 0.15W PC PIN TOP $0.57
R1-R6 - CF14JT2K20CT-ND RES 2.2K OHM 1/4W 5% AXIAL 10/$0.40

C1 - 493-1558-ND CAP ALUM 1000UF 20% 25V RADIAL $0.86
C2, C5 - 399-4491-1-ND CAP CER 0.1UF 50V X7R AXIAL $0.25
C3 - 399-6596-ND CAP ALUM 1UF 20% 50V RADIAL $0.16
C6 - P5139-ND CAP ALUM 220UF 20% 16V RADIAL $0.25
C4 - P5529-ND CAP ALUM 100UF 20% 16V RADIAL $0.23

Heat Sink for IC1 - HS198-ND HEATSINK TO-220 VERT MNT .75" $0.66

Breadboard - SBB830-ND BREADBOARD GENERAL PURPOSE PTH $6.49

Jameco parts:
https://www.jameco.com/z/CD4017-Major-Brands-CMOS-Decade-Counter-with-10-Decoded-Outputs-DIP-16_12749.html $0.45
https://www.jameco.com/z/TLC555CP-National-Semiconductor-Standard-Timer-Single-8-Pin-Plastic-Dip-Tube_761272.html $0.89

If you aren't comfortable reading electronic diagrams I can draw a wiring diagram picturing the actual components.
I decided to power the light bulbs from the AC side of the transformer. They will work fine, and this design allowed me to use a lower power bridge rectifier and smaller value filter capacitor.
C4 should be physically located near the relays, and C2 near IC2 (that is not indicated in the diagram).
The timing of the sequencer is adjustable as shown on the diagram.

[Point353]

I like using Digikey or Mouser Electronics as my parts suppliers, but they don't seem to carry many of the now-older DIP-style integrated circuits. They pretty much only carry the Surface Mounted versions.

IC2 - TLC555 Timer - Jameco
IC3 - CD4017 Decade Counter - Jameco

Jameco parts:
https://www.jameco.com/z/CD4017-Major-Brands-CMOS-Decade-Counter-with-10-Decoded-Outputs-DIP-16_12749.html $0.45
https://www.jameco.com/z/TLC555CP-National-Semiconductor-Standard-Timer-Single-8-Pin-Plastic-Dip-Tube_761272.html $0.89

The TLC555 is available from Digi-Key in a PDIP as P/N 296-1857-5-ND.
https://www.digikey.com/product-detail/en/texas-instruments/TLC555CP/296-1857-5-ND/277502

The CD4017 is available from Digi-Key in a PDIP as P/N 296-2037-5-ND.
https://www.digikey.com/product-detail/en/texas-instruments/CD4017BE/296-2037-5-ND/67253

Mouser has both of these parts in stock, as well.

[peteski]

The TLC555 is available from Digi-Key in a PDIP as P/N 296-1857-5-ND.
https://www.digikey.com/product-detail/en/texas-instruments/TLC555CP/296-1857-5-ND/277502

The CD4017 is available from Digi-Key in a PDIP as P/N 296-2037-5-ND.
https://www.digikey.com/product-detail/en/texas-instruments/CD4017BE/296-2037-5-ND/67253

Mouser has both of these parts in stock, as well.

Thanks!  I guess their search engine is not perfect. All I was finding were the MINI-DIP (SMD) packages.  But then again, it was probably a human error on my part.    I was really surprised that neither distributor was carrying these parts. But they still do.