37lover

Topcat, Yes, sorry my typo on the C1 value - I have used 220nf. Looks like I might be replacing the 555 as a first remedy. Have uploaded some photos of what I built but probably a bit messy so please be kind. I think I will try and rearrange the R1 and R2 fitting so it is a bit neater, and clearer to see.

Thanks, I will check the 555 again. Unfortunately you assume incorrectly about anti-static precautions; yes if I was delving inside my computer but no for this sort of hobby circuit. This might not appear for a while as I am attaching some photos of my built circuit, not the neatest but I had hoped it was physically acceptable and the circuit schematic I had used. The dashed line is the link pin 6 to 2

I don't know if this extra information helps If I hold one leg of the bi-polar led against the 4017 pin 14 [the input from the 555] and touch the other 4017 "output" pins the led illuminates. This is the basis of how you set up the bi-polar so one leg would "sink" via the other pin. I don't know if this proves the 4017 is okay, or not.

Topcat, Need some help troubleshooting; circuit hasn't worked. I didn't have the small capacitors so had to wait for them, delivered today. Just to follow up on your point 2 above the 100nf and 22nf capacitors are surely non-polarised; it doesn't matter which way round they are connected. I say this because mine are TDK Polyester Poly Box and have no marking to identify a positive connection. When I powered up for the first time the bi-polar led lit up white, and stayed white. I checked the led by applying 12v direct to the legs, swapping connections and it works fine - red one way, white the other - and without any resistor not excessively bright. I might try it with a range of lower voltages to find out the minimum forward voltage(s). I checked the output from the 555 pin 3 and this appears constant at 11.47v; I know the output should be high for 143 millisecs and low for 71 millisecs with a theoretical frequency of 4.65Hz so I am suspecting my multimeter is not sufficiently sensitive to see this on/off and shows the mean [mostly on!]. By the way power to the 555 is a regulated 12.03V. There is now no output from the 4017 but it must have given something originally to light up the led white. Possible checks; disconnect the 555 output from the 4017 and connect to a led + resistor - would my eyes be able to detect if it flashed at 4.6Hz? [i have reasonably good eyesight but could get my daughter to observe!] Although I soldered most of the 4017 pins to the "breadboard" only 7 of the 16 are used so swapping for another IC would be too much trouble.

I didn't pick up this thread earlier as I thought it was simply about track voltage but now see why the question was asked. I have fitted a flashing red led to several of my Guards Vans; one was a proprietary kit bought off Ebay and the others used some basic electronic circuits cobbled together by myself. They all used a bridge rectifier and then a voltage rectifier; I experimented with a 555IC to get the flashing but it was much simpler to use a Flasher IC bought of Ebay, I think I used a 1Hz rather than the 2Hz. No on/off switch so they are on once placed on the live track.

Topcat, Sorry, quick question. You show three capacitors on your circuit; C1 and C2 appear to be drawn as non-polarised but can these be polarised, obviously with positive leg on the 12V side? Is your symbol for C3 representing a polarised capacitor? I'm asking because I have lots of polarised but no non-polarised capacitors!

Rog(RJ), Thanks but I don't have an Arduino, and do not wish to buy one, so I'm looking for a simple electronic control system for the led's that I can solder up and place say under/on the plane stand so it just needs a power connection to turn on the lights. I think the proposal from Topcat will work fine and the last few posts are simply discussing a few variations.

Topcat, Tried RS again and this time I managed to find the offer for 50 pcs. I'll hold off purchase for now and see how I get on with the 12V circuit. I will trial and error a few set ups to see how to connect 3 x 12V leds. I have thought, as a last resort, I could connect one led to Q0 and Q5, the second led to Q1 and Q6 and the final led to Q2 and Q7. This is to "spread" the current/voltage demand. Visually the first two leds are on opposite sides of the fuselage so I don't think the slight timing offset would be noticeable, the third bi-colour led is at the very tip of the tail.

Hi Topcat, You probably thought by my recent postings that I am frequently looking at the Hornby forum but sometimes I take a break! Many thanks for the circuits, I have printed both and I understand them and they seem well within my soldering capabilities. I spent quite some time last night researching CMOS Buffers, and hopefully now understand them a little better. But I could not find a source of the TC7SET34F you specified; well, I could buy a reel of 3,000 for about £70 or there was a Supplier in Ireland who would sell 10 for £2 but then charge £12 for delivery. So I went to bed. This morning I've tried a wider search on Ebay just using the "CMOS Buffer" title and when I filter for UK only I am down to a list of 60. I need time to check to find a suitable one unless you are able to advise. Thanks for all your work; I've got the led's on order and they should arrive for the weekend, which will be my first opportunity to start assembling the circuit(s).

Topcat, Thanks for advancing my electronic understanding. Flickering leds are available in various colours and I'll be experimenting with a single flicker led [orange or yellow?] and maybe combining with a red normal led. Lots of options. BTW I was pleased to read your comment about the "on" duration of a flashing light and how brief it could be for the eye to recognise, something I had been thinking about and I believe the shorter "on" period, relative to the "off", may actually look better - but not quite as short to give a strobe effect.

96RAF, I think a 3mm led is too big even though the model is 1/72 scale [3ft long!] and certainly do not want to think about using a decoder or sound although that would be spectacular! I will be incorporating cabin [pilot and passenger], landing, reheat [flickering], and nav lights but these will only require a supply voltage and my intention is to try and get them on only one or two circuits. Topcat, I am hoping to run wires/cables down through the stand and have a mains power source, via suitable transformer of course. That's an interesting point you make about connecting the legs of the bi-polar led, I presume the non powered output [either Q0 or Q5] acts as a ground - didn't know that. Will look out for the circuit.

Topcat, Would it be possible to use just one counter if we did the following Combine Q0 and Q1 with a CD4071 OR gate to drive the "red" end of the LED, leave Q2 to Q4 unconnected for the off interval between red and white on, and combine Q5 and Q6 to drive the "white" end of the LED. Then Q7 to Q9 provide the interval before the counter resets and goes back to Q0. I realise this would change the on/off ratio. Isn't the Clock timer function provided by a single 555? You say this is foolproof and better than the 555 solution so I am all for this latest option I've noticed that the Ebay Seller is also offering Bi-colour LEDs with much lower forward voltages [2.1/3.1V] but currents up to 30mA which I think from your earlier posts would be too high to use with the components we are discussing I have a few Cascade counters in my electronic stores! Left over from my failed attempts to build a circuit to light a circle of leds for the "Buzzards" of Star Trek. The Buzzards are the rotating front ends of the nacelles [engines].

In my earlier years I lived in Suffolk and often had Vulcans flying overhead; beautiful plane. Lighting; I thought I would need the bridge driver to reverse the voltage. But put that aside I will try the 555 solution.

Topcat, Space isn't a problem. This is where I come clean and say the flashing red/white led is for the leading edge of Concorde's wings where they join the fuselage and at the very end of the tail! As well as modelling trains I also enjoy plastic kits, mostly planes - I collected many kits during my "working" life and as I am now only working part time I have the opportunity to start assembling some of them. I have a 1:72 scale Concorde, ditto Vulcan, ditto Lancaster BIII, and 1:500 Enterprise [start Trek] plus a mixture including iconic cars and WW2 tanks! I appreciate what you said earlier about the current draw but I have found a L293d H Bridge Motor Drive IC on Ebay that claims to have a 600mA output. Again my understanding of electronics is very limited but could this be "switched/controlled" by the lower current outputs of the 4016 decade counter? Thanks for your efforts so far.

Topcat, A few days, weeks even, is not a problem. I am very grateful for your help.

96RAF, Thanks for the link. I could possibly use the Level Crossing LFX1 but at £15.75 +PP I don't really want to risk it, plus there would be no pause between my red & white flashing. Topcat, Thank you for explanation and suggestions. I only recently [yesterday!] came across the 4016 and it interested me as potentially a way to flip the polarity. I did note that the maximum current, as per the tech specs, is only 10mA and I thought that might be too low. I appreciate leds can draw 25mA but often they will work on much lower currents. I did see a 4316, which I presume is a "bigger" version of the 4016 and this has a rating of 25mA but costs a lot more! I have loads of 555's and would be very grateful if you could draft a proposal. The led is listed on Ebay under the following heading LED Bi-Colour Water Clear 3528 PLCC4 SMD 120Deg 12V 10mA Red/White The specs are 12V typical forward voltage, forward current 12mA. As for timing periods, I need something to visually give a flash of red, off for a short period then flash of white. I think an on/off total of 1 second [for red on and off before the white comes on] could work but perhaps better at 1.5 seconds. I am lost trying to set the on period; 0.25 of a second? Red and White will have similar on periods. Please let me know if this is sufficient information. Regards Martin

I am looking for an electronic circuit that can alternate polarity feeding a 2mm dia 2 leg bi-colour 3V led. You may know a 2 leg bi-colour led, in my case red and white, changes colour when the polarity is "swapped". I am trying to get a circuit that will give a brief flash of red, a short delay, then a flash of white, and the cycle repeats. I've scratched the surface of available electronic components and think a "Quad Bilateral Switch", such as a HCF4016, might work [with a 555 and 4017IC, that are commonly used to give a "Knight Rider" sequence] but I am out of my depth. The alternative is to use a 3 leg led with a common anode and simply alternate the feed, disadvantage of this is that the smallest led is 3mm and I'm hoping to use something smaller.

Many members quote frame spacings, but without mentioning the frame cross-section sizes. Deflection of the upper board, between frames, is dependent on frames spacing but the whole board can deflect if the frames are not sufficiently "stiff".

Only just caught up with this thread and obviously there are many variations. I am sorry but my mouse must have been out drinking with 96RAF's but I am trying to show how you could continue the sidings onto the main lines, there is still a reverse loop - not so pretty but still effective for changing the running direction.

Apologies for dredging up an old thread but the latest forecast delivery date on this website is now showing Summer 2023!

ColinB, You are correct that 0.03A quoted by the OP is 30 milliamps but that is not what you typed!

Obviously some like it as it is now "Out of stock"; I guess that means the limited edition of 1,500 all taken with pre-orders. I wonder if Hornby will do a "Sir Tom" and increase the production number once they realise they have underestimated the demand.

JJ, Not sure why you felt the need to start a new thread; price increases have been discussed at length in a thread titled "Has there been a price increase?" and the last post to that thread was only a week ago.

You guys really annoy me by stating soldered fishplates are a no-no. They may not be as good as soldering direct to rails but my layout has been running for over 12 years with soldered fishplates and no dead spots yet. Admittedly almost all my fishplates are connected so there is a lot of inbuilt redundancy. So please stop saying it is bad practice, it may not be the best but it is okay.

Sorry, I stand corrected. Mis-use of terminology. Of course it will "drive" the led, it's probably obvious that the led has to be connected back to the original power source and that was I was trying to note.