Dapol semaphore signals

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(*As in the proper attitude for a modeller - not the attitude of a 'proper modeller'. Let's not start the debate about 'proper modellers' here, I'll leave that to the other place as well).

I used to be a proper modeller..................cessna 172s,,,, beech barons,,,,,, spifires
Rich123 could you possibly add a link to them please?
Thanks
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[Rich123]

Hopefully I've copied the links correctly below (you might have to cut & paste them). I'm not that great with IT. Since my last entry I've noticed that Hatton's have another entry for a bracket signal - 4L-001-005 Signal - motorised, GWR bracket. Maybe this will become the right hand junction bracket two arms.

http://www.hattons.co.uk/409069/Dapol_4 ... etail.aspx

http://www.hattons.co.uk/409070/Dapol_4 ... etail.aspx

http://www.hattons.co.uk/409071/Dapol_4 ... etail.aspx

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Many thanks Rich123.
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[abenn]

I recently purchased a single Dapol N-gauge home signal from Hattons, and connected it to 9v DC. The leaflet says "We recommend using a 12vDC stabilised power supply.", and the wiring diagram says "14vAC OR 9-12vDC". I've got a 9v line for other electronics on my layout, so I tried it and it works.

A couple of days ago, being happy with the home signal so far, I bought a single distant signal. It's leaflet says "16V AC power supply (not 12DC under any circumstances)".

I haven't connected the distant signal yet, so my first question is, is the track supply for my Lenz DCC system okay as the AC source for the signal? Second, does anyone know whether it will work on 9v DC like the home signal?

P.S. Since writing this I've been to the link near the beginning of this thread, and it seems that Dapol have had a lot of problems with these signals and, most importantly, have for the past couple of years been recommending either AC or DC, as per the leaflet that came with my home signal. But they still seem to be unreliable

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Does anyone else make pre-made motorised signals like these?
I don't think I could build one of the signal kits available well enough for it to work properly.
Thanks
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[Suzie]

Don't use DCC directly it will cause damage, and 16V AC will cause excessive heating. Regardless of what it says on the packaging you should use 9v DC for Dapol semaphores. Use of anything over 9V will just cause more heat to be dissipated, and the LED to be brighter (if the signal has one). LED should be bright enough on 9V DC

[abenn]

Yes, the light was quite bright enough (too bright?) on 9v DC. It stands to reason the lower voltage -- so long as it's enough for the signal to work -- should cause less heat, so 9v DC is what I'll use for both my signals, in the hope that they'll last longer than those of many contributors to the referenced thread.

I find it amazing that a company like Dapol should be (or is it past tense?) so confused about what is the correct type of power for their signals. Presumably the distant signal I got with the specification of 16v AC is older stock.

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I'm puzzled as to why they chose this mechanism in the first place, doesn't know which way it's going and has odd power requirements for DC or DCC.

[abenn]

Most of the posts I read in the link were quite old, so maybe Dapol have improved the reliability now. I suppose, if the worst comes to the worst, I could remove Dapol's actuator and electronics and somehow attach a standard servo, of the type I've used for all my points.

[Suzie]

Dapol are quite insistent that their signal is perfect in every way and is just what the customer wants.

You should be able to operate the signal on a voltage as low as 6V DC if required to reduce the brightness to sensible levels. While the LED is run from the supply voltage via a 820R resistor, so brightness is dependant on supplied voltage, the 'works' is powered via a 3.3V regulator, so any voltage higher than 6V will just be dissipated as excess heat.

[abenn]

. . . . You should be able to operate the signal on a voltage as low as 6V DC if required to reduce the brightness to sensible levels. While the LED is run from the supply voltage via a 820R resistor, so brightness is dependant on supplied voltage, the 'works' is powered via a 3.3V regulator, so any voltage higher than 6V will just be dissipated as excess heat.

If the 'works' are running off a 3.3v regulator, why on earth do Dapol insist in their instructions on 9-12v DC or 16v AC, depending on which version you read? From my limited experience of regulators, 3.3v should be obtainable from a supply voltage as low as about 4.5v Also, if the LED were run off the 3.3v regulator, with an appropriate resistor for that voltage, then its brightness could be fixed at a sensible level, which would be independent of input voltage.

There must be a reason for them designing it the way they have, but I can't see it.

[Gordon H]

There must be a reason for them designing it the way they have, but I can't see it.

My suspicion all along is that they (Dapol) had very little to do with the detailed design. They probably provided a vague, improperly specified drawing on a piece of paper and gave it to someone in China who produced what they thought was needed. I would be happy to be proved wrong, especially if the real story comes to light as a result.

[Suzie]

I suspect that they built the prototype and then realised that the (white) LED would not work on 3.3V since its forward voltage is higher than that. They should of course have used a yellow LED to get proper oil lamp colour which could run from 3.3V with a resistor.

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The whole story of these signals shows a total lack of information about their intended use and the methods of operation available, ever having reached the developer who produced the design. Proper investigation during development would almost certainly have resulted in one of three methods of operation.
1) a simple solenoid and spring device either on or off.
2) a double solenoid device
3) a servo device, which could have imitated real life movement (bounce).
All working from voltages available on a model railway.

[abenn]

I suspect that they built the prototype and then realised that the (white) LED would not work on 3.3V since its forward voltage is higher than that. They should of course have used a yellow LED to get proper oil lamp colour which could run from 3.3V with a resistor.

White LEDs that I have experience of, both through-hole and SMD, have forward voltages between about 2.5v and 3.2v, so they should run on 3.3v with a suitable resistor. But yes, a yellow one would have been a better colour irrespective of any voltage constraints.

Today I was doing the final installation of my two signals. Each has a relay, controlled by a PICAXE circuit which monitors the appropriate points' settings, which gives a 0.25-second 'blip' when required to change the signal. I tried my home signal with a 4-cell NiMh battery first, giving 5.17v at no-load, to see if it would work directly from my PICAXE 5v power supply, and it worked. But the distant signal didn't work on the 4-cell pack, but it did work on a 6-cell (7.2v nominal) NiMh pack. So I have them connected now to a regulated 9v DC buss that feeds my electronics. Hopefully that will give them a long life!