AC to DC conversion for LGB switch tracks

R

Robert Bianchi

Registered
Hi,
All of you wonderful members helped me in the past and I hope you can help me now. Label me a dummy: I have an outdoor LGB garden train and want to add a couple LGB switches (DC activated) to create a siding which will have automatic controls. My transformer has an AC accessory output of 19 volts and I need to convert it to DC to run the switches. I would like to use diodes (which I have) to move the switches each way, but am unsure of how to connect them to permit this to work and don't want to experiment and maybe burn out the switch motors.

I want to connect directly and not use a switch controller. Can anyone help?

Thanks,
Bob.
 
????????????

normally today all LGB turnout motors are AC.
if you got connectors for two cables, the above is true

if you got motors with three cable connectors, you got the old motors (from thirty-plus years ago), that run on DC.
in both cases you would work with diodes.
tell me, which type of LGB switch-motors you got, and i can describe how to set it up.

do you mean by automatic control, that you want, that the trains themselves activate and de activate each other?
 
Robert Bianchi said:
Hi,
All of you wonderful members helped me in the past and I hope you can help me now. Label me a dummy: I have an outdoor LGB garden train and want to add a couple LGB switches (DC activated) to create a siding which will have automatic controls. My transformer has an AC accessory output of 19 volts and I need to convert it to DC to run the switches. I would like to use diodes (which I have) to move the switches each way, but am unsure of how to connect them to permit this to work and don't want to experiment and maybe burn out the switch motors.

I want to connect directly and not use a switch controller. Can anyone help?

Thanks,
Bob.
Click to expand...
You make a Rectifier with 4 Diodes that will convert the Ac to DC. The rectifier will reduce the voltage some, possinssibly by around 1 Volt each depending on the Diodes.

rectifier circuit

If you Google as above, the 4th image in from the left is the simplest circuit that works. I have used this on my Dcc Track Tester to reduce the Track Current to DC, with a resister for the 12v DC Bulb that I use.
JonD
 
korm kormsen said:
????????????

normally today all LGB turnout motors are AC.
if you got connectors for two cables, the above is true

if you got motors with three cable connectors, you got the old motors (from thirty-plus years ago), that run on DC.
in both cases you would work with diodes.
tell me, which type of LGB switch-motors you got, and i can describe how to set it up.

do you mean by automatic control, that you want, that the trains themselves activate and de activate each other?
Click to expand...

Hi Korm,

Thanks for replying so quickly. They have 2 connectors, so must be AC. I'm using LGB 1700 track contacts to control the switches.

All the best,
Bob.
 
No, the two wire motors are DC not AC. They require DC current to be reversed to move one way or the other. Usually the LGB switch box is used which has internal diodes to half-wave rectify the incoming AC supply.

Here's a diagram found on mylargescale.com:
EPL%20Switch1.jpg
 
Hi Bob,
What do you mean by 'automatic control'?
Do you want a loco approaching from one direction to automatically switch the points to set a route?
Do you want a loco to enter the siding (loop?), and then stop?

Think we need a little more of your thinking??

PhilP.
 
Thanks Nick for the diagram. I'll try to decipher it for my train. Philp: The idea is to have two trains on the loop. One train enters one dead section and the switch activates the other train on the siding. I've already set-up the switches to do the activation. However, my problem is to have the 1700's that are just after the dead sections activate the switches the other way, etc. It looks like from Nick's diagram that I need to have a diode for each switch movement.

Nick: In the improved diagram, assume the 2x470u/35V are capacitors. What do they accomplish?

Thank guys,
Bob.
 
ntp..., be carefull.
the epl switches , that robert has, react not well to "real" DC. that is, why the system works with pulsed DC (or, in other words, with halved AC).

robert, if you got the two wire switches and the 1700, you got the complete epl automatic components.

take a read here (chapter Taking Control) http://kormsen.info/lgb-manual.pdf
if you got more questions, just shoot away.

ps if you use the 1700s, you don't need additional diodes.
connect black from power to the middle of 1700, choose one of the other two contacts for the orange wire, that goes to the switch.
the orange wires from two differently connected 1700s go together into the orange contact of the switch. (you can unite them anywhere between 1700 and switch)
the white goes direct from power to switch.
if the switch does work in the "wrong" direction, just change the side of the orange outgoing cables at the 1700s.
i do often connect two turnouts to the same pair of 1700s. when i use three or more, the reedcontacts in the 1700s burn out.

magnets, that come out of computer harddisks are very good for activating 1700 reeds.
 
korm kormsen said:
ntp..., be carefull.
the epl switches , that robert has, react not well to "real" DC. that is, why the system works with pulsed DC (or, in other words, with halved AC).
Click to expand...

Korm,

You seem to have explained that all rather well..

Totally agree with you re not operating EPL drives on pure DC. A few years before LGB introduced the EPL drive, Lego produced a point/accessory motor with a two wire drive, but this relied on a neat DC feed with polarity that was reversed between movements instead. As a result today these often tun up damaged or burnt out, but EPL drives rarely do (if they have been used properly).

I love the way the LGB units capitalise on the half wave nature of the EPL. You can connect as many 1700/17100s reeds or 5075N/5175 type switches into the orange wire leading to the drive.

I also use a yellow 5080N/51800 type control box to switch the power in the black AC wire leading to the the automation reeds on and off. So automation can be only on when you want it, but the EPLs can still be switched by a 5075N/51750 type unit whether the automation is on or off.

LGB designed this well. Just using as intended will give good results.

Incidentally I always place my reeds 'very late' in the section immediately prior to the isolated section where the loco is required to stop, so it is the last thing the loco runs over before it stops. My logic in placing them there is that the loco is less likely to stick over the reed causing the burst of power to become a constant flow.

James
 
Last edited:
I'm not sure if any of the replies have pointed out that you have all you need to make your auto section work! the means of the polarity change is accomplished with the 1700 Reed, there are three terminals on the 1700 only two are connected at anyone time. If you like, there is a + or - output from the 1700 to switch left of right. I would suggest you obtain a copy of the EPL manual a cup of what ever you fancy and have a read.......................Paul
 
Thanks folks. All is explained and understood. Especially thank Korm for the reference to the manual which is a big help.

All the best,
Bob.
 
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