Lots of questions here. Firstly, is it necessary to wire the frog of a point? Shouldn't the frog polarity be switched by the switch rail? Well, yes it should. But it didn't in two out of six cases on my so-far laid track.
In a spectacular and unprecedented exercise in forward planning, I had wired the point frogs in advance, just in case. So it's a matter of wiring them to a switch activated by the point motor.
Hmmm. I had planned to use a micro switch to drive the LED indicators on my control panel. Now I need another switch to change frog polarity. Is there a switch that can do both jobs?
Yes there is. Peco's PL15 switch does just that. But at £5 a throw it's too expensive to consider, with all the points I'll be installing (50+) over time. There is a DPDT microswitch that may work - a DPDT switch is basically two single switches changed by the same mechanical device (in this case, the point motor). I've ordered one from Maplins to test it, and then will source a cheaper version if it works in principle. (Maplins are consistently more expensive that other online sources such as All Components and Rapid.)
Showing posts with label Wiring. Show all posts
Showing posts with label Wiring. Show all posts
Thursday, 13 January 2011
Thursday, 25 February 2010
LED Point indicator wiring
My intention is to have, on a mimic board, route indication driven by the points settings. Green indicates the route is set, and red means the route has points set against. So what is required is a switch on the point motor that will light a green LED when set in one direction, and will light a red LED when set the other way.
The solution, after a lot of googling is this. A microswitch is fixed to the bottom of the point motor. The COM tab is wired to the +ve feed of an ancient Triang uncontrolled DC power supply. The OFF tab is wired to one leg (anode) of a bicolour 3 legged red/green LED via a resistor, and back to the -ve terminal via the common cathode (centre leg). The ON tab is wired to the other leg (anode). This means that this LED will light green when the point is set "off" or normal, and red when switched. An identical LED is wired in the same way, in parallel, but the opposite way round, so it shows red when the point is set "off" or normal, and green when switched.
Here's a diagram:
And here are photos of the test wiring:
Notes:
I initially tried wiring with two-legged bicolour LEDs, but to get the desired effect requires extra diodes and other electronics stuff - so it's simpler to use the 3-legged versions. I used Maplins for the test but they are cheaper at All Components and Rapid.
I used a cheap microswitch (50p at Rapid, £2 at Maplins!) which will be glued to the bottom of each Peco PL10 motor. You could use Peco PL13s but they have a bad press, and they are much more expensive (£2.80-ish). Here's a photo:
Resistors: I used 680R metal film resistors from All Components, at 5p each. I could have used slightly lower resistance, perhaps 540R - there's a formula to work out the minimum resistance on Brian Lambert's site.
The solution, after a lot of googling is this. A microswitch is fixed to the bottom of the point motor. The COM tab is wired to the +ve feed of an ancient Triang uncontrolled DC power supply. The OFF tab is wired to one leg (anode) of a bicolour 3 legged red/green LED via a resistor, and back to the -ve terminal via the common cathode (centre leg). The ON tab is wired to the other leg (anode). This means that this LED will light green when the point is set "off" or normal, and red when switched. An identical LED is wired in the same way, in parallel, but the opposite way round, so it shows red when the point is set "off" or normal, and green when switched.
Here's a diagram:
And here are photos of the test wiring:
Notes:
I initially tried wiring with two-legged bicolour LEDs, but to get the desired effect requires extra diodes and other electronics stuff - so it's simpler to use the 3-legged versions. I used Maplins for the test but they are cheaper at All Components and Rapid.
I used a cheap microswitch (50p at Rapid, £2 at Maplins!) which will be glued to the bottom of each Peco PL10 motor. You could use Peco PL13s but they have a bad press, and they are much more expensive (£2.80-ish). Here's a photo:
Tuesday, 16 February 2010
Wiring thoughts
Was directed to Brian Lambert's site via the N Gauge Yahoo! group. Brian's site is excellent, loads of detail and practical experience, clearly explained.
I need to think about wiring now, before laying track, as holes for dropper wires will have to drilled for wiring as track laying progresses, and I don't want to make it up as I go along.
From Brian's site, and other readings, here's my basic track wiring plan:
Use a bus architecture for the main rail power feeds. 'Bus' is a fancy word for cable, and it will run around the underside of the baseboard following (roughly) the track main line. Two wires are required (live and neutral) and I'll use the red and black wires from household electric mains cable (2.5mm twin core and earth).
I'll then drop wires from the rails at appropriate places. Probably I'll use the wire-soldered-to-rail-joiners method - easy to solder first and join later, rather than faff around with soldering to the outside (ugly) or underside (easy to melt sleepers) of the rail.
Dropper wires will then be connected (terminal blocks or soldered) to wires that will then run to the bus.
Point wiring can be considered separately, except when track polarity needs to be switched by a point motor. The only place I think this applies is the long crossing. Polarity of point frogs is switched automatically from the switch blade making contact with the stock rail. (I'm using Peco code 55 electrofrog points throughout.)
Questions:
Should I draw up a full wiring plan? Probably.
Do I want to wire the switch blades of points, or depend on contact with the stock rails? My inclination is to rely on the stock rails, as wiring up the point blades involves intricate soldering (with the risk of messing everything up).
At least I don't have to worry about isolated sections, as my DCC decision removes this requirement.
I need to think about wiring now, before laying track, as holes for dropper wires will have to drilled for wiring as track laying progresses, and I don't want to make it up as I go along.
From Brian's site, and other readings, here's my basic track wiring plan:
Use a bus architecture for the main rail power feeds. 'Bus' is a fancy word for cable, and it will run around the underside of the baseboard following (roughly) the track main line. Two wires are required (live and neutral) and I'll use the red and black wires from household electric mains cable (2.5mm twin core and earth).
I'll then drop wires from the rails at appropriate places. Probably I'll use the wire-soldered-to-rail-joiners method - easy to solder first and join later, rather than faff around with soldering to the outside (ugly) or underside (easy to melt sleepers) of the rail.
Dropper wires will then be connected (terminal blocks or soldered) to wires that will then run to the bus.
Point wiring can be considered separately, except when track polarity needs to be switched by a point motor. The only place I think this applies is the long crossing. Polarity of point frogs is switched automatically from the switch blade making contact with the stock rail. (I'm using Peco code 55 electrofrog points throughout.)
Questions:
Should I draw up a full wiring plan? Probably.
Do I want to wire the switch blades of points, or depend on contact with the stock rails? My inclination is to rely on the stock rails, as wiring up the point blades involves intricate soldering (with the risk of messing everything up).
At least I don't have to worry about isolated sections, as my DCC decision removes this requirement.
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