Content → Hardware → GCA

• The GCA modules

See below for info.

MGV85 is mostly an exact copy of the LocoBuffer (Without USB) of John Jabour.

It is added to provide an easy way to connect MGV50 units together, and also provides a 15 Volt 3 Amp power supply for the Loconet.

To be able to connect standard Loconet devices like FredI or DCS100/200 and many others, an extra RJ12 connector(=J4) is also on board.

Jumper JP1 is to enable power to RJ12 connector.

This is to avoid conflict with connection to Intellibox or Twincenter, or DCS100/200.

If FredI is connected to J4, Jp1 must be set ONLY when NO Central unit (like MGV110, DCS100, IB) is connected to the system

The communication inside LocoNet is made by short-circuiting the communication line (J2{3}) to ground.

This means of course that there should be some kind of power on the line.

That 'power' is a current source of 15-20 mA somewhere connected to the communication line.

The most logical place is on the computer interface. Jumper JP6 must be placed to enable that current source to LocoNet line.

IMPORTANT NOTES:

Always use dedicated transformer for GCA85 (16V-18V 52 VA), which is not used for anything else.

Also do NOT connect brown connection (like on Marklin transformers) to any connection of MGV85 or anywhere else in the LocoNet!

Connecting so could cause serious damage to Loconet modules and PC!

This of course unless some connections are specifically indicated.

Copying and building this unit is very much encouraged.

The responsibility of doing so, is ALWAYS totally for the user himself.

It is working satisfying on many railroad tracks.

I have given all efforts to make this unit safe, but even so, no responsibility can be taken for failures of any kind.

LocoNet is a trademark of Digitrax, Inc.

A nice conversion to USB is possible now.

Simply replace J3 (Connector to COm port PC) with a special USB-RS232 Female connector.

See picture below.

If you are interested, ask Peter at peter@phgiling.net.

Important note !! :

Remove both jumpers if central station (i.e. Intellibox, Twincenter, Digitrax) is connected to J4.

MGV85 connections

The best suitable cable is Cat 5 Ethernet cable. For all cables together a maximum length up to 200 mtrs is allowed. MGV85 connections

Standard full wired male to female 'extension' Rs232 cables are allowed, but up to a certain limit.

It is never experienced how many can be used, but a few do not disturb the communication.

Please remind that this type of cable is not able to handle the full 3A of the power supply!

Any full wired standard male/female 'extension' RS232 cable is suitable.

J3 (computer COM connector) could be replaced by direct USB connector.

Ask peter@phgiling.net for info.

Components

The PIC16F873 should be programmed with firmware as below. Contact Peter Giling if you need help for that.

Use extra nut between PCboard and VR1/VR2, to improve cooling.

With the given values for R11 and R12 (1K and 10K) the power voltage to LocoNet will be 13,5V.

The choice of C1 is depending on total Amps needed. If no more that 2 Amp is used, a 4700 uF Elco will be sufficient.

• http://bazaar.launchpad.net/~rocrail-hardware-team/rocrail-hardware/trunk/files/head:/ln/lb-2/

For PCBoard and/or programmed chip : contact

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