TMWDCC digital command station, test setup
Vero boards from left to right: Processor Board TMW1 (connects to
PC printer port),
Power Supply TMW6 (2A), and Midibooster Board TMW5 (1.5A)
(under construction are The Ackdetector Board TMW3 and The Relay Board TMW4).
All stations will be fitted with Power supply and Midiboosters.
[12/10/99] Finally got the TMW boxed. The box will have a see through cover
for the curious visitors to see at Turku Exchibition 30th--31st Oct. 1999.
During fitting found some cold joints from the relay card. Perhaps the
programming will work better after re-soldering!
Olli installed DCC-connectors for feeding the DCC underneath the baseboards.
We used crimp connectors and 15-pin D-connectors: The 15-pin D-plug will short all sidings etc. feeders into one, so that the power routing turnouts will be bridged. If we want to use conventional power (no DCC), removal of the plugs will get us back to old sysytem (power routing turnouts).
Opa (one of our members) has fitted old Arnold decoders we have got (Thanks Lars!) to our Dm7 rail cars (Swedish Y6 models repainted by Tomppa, another member of the club).
[31/10/99] Exhibited the setup at Turku exhibition. Operated the TMW for two six-hour
sessions with very little problems. The feature we were not aware of was that the
throttles are inoperative while keying in assignment commands. We also experienced
a peculiar problem due to too weak a power supply (Roco starter set transformer!):
when the internal overload cut-out started to intermittedly cut out power of the
transformer we succed in brown-out'ing the PIC in such a state that all locos switched
to dc. This kind of situation should not happen if the TMWDCC is assembled correctly
and fed directly with a power supply of correct capacity. If we would have operated the
TMWDCC with the latest version of software the emergency halt would have halted
the trains as it now also operates the relays of the relay card!
While another operator was running a loco from behind, the other operator came close
to the loco and, with his Nokia Communicator open, acted as if he was operating the
loco with it -- the first TMWDCC-WAP connection ;)
[07/11/99] In the morning I went to the Old Toy Swap (arranged by Marklin Club
of Finland) and bought two old Märklin transformers for the TMWDCC, went to
the club and retuned the Ackdetector with resistor in relay card and relying
on the LED's installed to the Ack detector output. I'm now able to read all
the decoders we have: Old Arnold, Roco, Lenz and Probst!
I also managed to install the latest (1.31) version of TMW software. All looks
We still wish to get the disconnected throttle loco assignments visible on screen, and possibility of assigning locos to disconnected throttles.
[25/04/00] The Model-Expo-2000 exhibition lasted four days, total of 30 hours of running. TMWDCC was operational all the time, and didn't need any booting or special attention during exhibition.
As it was impossible to change functions or see the assignments of disconnected throttles the operators got somewhat irritated. Occasionally someone went to change the assignments during running without warning others and this caused nuisance (but these are features of TMWDCC).
The younger boys enjoyed the freedom of DCC too much: we had two full speed head on
collisions within five minutes! The lack of forced dicipline of the DCC in general
caused the older members to long for the old system of no DCC!
We tried the "reverse DC" operation with one loco [LE103XF: CV29.2=0 and CV50.2=1].
We installed a DPDT switch to the wires between layout and booster so that with the
switch we could switch the layout into ordinary DC power pack.
This is the first test throttle: 100k potentiometer and a switch connected
directly to D15 connector. Four throttles should be possible to be connected
to a single game controller card (speed control potentiometers in place of
joystick potentiometers and direction switches in place of fire buttons).
Maximum of 8 throttles should be possible to be connected using two game
controller cards (the other card must be modified to change the port address).
A separate bus will be fitted with RJ-45 receptacles for throttles.
[28/04/02] Exhibition over, the system worked well, and will be developed further.
[08/02/03] The PC-eliminator was running during the XX National Model Railway Days 2002 16th-17th Nov.2002 We wished a location by the wall, but instead we were placed in the middle of the hall with walls and roof far away. We used 8 IR-receivers and got fair operation. The Helsinki MRC's Xmas exhibition was better, as the layout perimeter was smaller. We had two Roco cranes in operation. One of the IR-throttles developed a fault during the first day of the show (It refused to change address). The fault presisted allthough the processor was changed. We have now erected the layout to the club and I hope to be able to search for the remedy the problem of this one throttle.
[28/04/03] Last weekend was the Model-Expo show in the old Helsinki Ice Hall. We operated the three day show with PC-Eliminator and TMWDCC hardware. I havent yet sent the faulty Lenz LE103FX decoders to Lenz for repair (need the extra capacitor next to zener), so we were guaranteed to have some runaway trains. the above mentioned throttle not changing address was fixed (adjusted the speed pot trimmer). It seems that the system is forgetting the addresses of locos or something as we quite often had to reset the locos by keeping them off the metals (tilt) for a few seconds. I plan to modify the PC-eliminator code so that it will display the addresses of cabs in sequence if nothing more pressing is to be displayed so as to make sure the addresses aren't lost during running!
[24/11/03] I have now upgraded the PC-eliminator software so that is not allowing loco
(address) capture in case the previous owner has the speed in non-zero position (diplay
See Tillorps Mekaniska Werkstad for complete description of TMWDCC by Lars Lundgren.
Dean Probst decoder
This is the first decoder built, it uses PIC16F84/10 controller (programmed with David Tait's programmer), and L272M power op-amp. The original Probst design includes functions outputs and is designed to be assembled using surface mount devices (SMD). This is built on a 23 x 21 mm (9 x 8 holes) piece of Vero board and connected from below with wire-wrap wire.
The components on the lower left corner are: 5V regulator (top),
diode bridge (4 1N4148 diodes under black and red wires), 33K resistor between
track and PIC input (bottom left), two 10K resistors forming a voltage
divider reference to power op-amp (bottom right), 10 uF tantalum capacitor
to filter 5V to PIC (middle) and 8 MHz crystal for PIC (right).
[14/05/99] No power to decoder for 0.5 -- 1 second may cause complete loss of
control to decoder until another short cut of power is applied. Short loss
of power seems to cause no ill effects (still not fitted into a loco!)
[16/06/99] Assembled the second version of Probst decoder, this time I cut one row of pins from both ends of the PIC to save space and tried the DS1818 Reset chip (Thanks Lars!) to replace the Microchip reset. As DS1818 is designed for max. 5.5 volts I replaced the voltage regulator to 5 volts. The reset chip trips at too low a voltage (3.3 V) so an additional diode in Vin pin of the reset chip was added to make the chip reset earlier. This helped, but the operating margin is narrow. The voltage regulator could now be changed back to 6 volts to give more margin as the above mentioned diode will lower the input voltage to reset chip to approx. 5.5 volts.
The Mk II receiver is to be fitted into a small diesel loco (Bjurström), an
etched kit from Kaj Wikberg.
[25/04/00] Bjurströn now has the Mk II decoder with Mk I decoders brown-out circuit. At Model-Expo-2000 Bjurström was operated for a little time, but as the small wheels got dirty so quickly it was taken off the layout. Otherewise no problems with brown-out (didn't go crazy!).
[30/11/01] I've decided not to investigate the present decoder design any further, as I belive I've achieved my goals of proofing to myself that it can be done ;) The design is not so good (halts for so long after dirty spot) that modification to the PIC software and other measures would be needed. I suggest those willing to investigate further to look into Mr Bolton's design at Model Electronics Railway Group's (MERG) website. There are lot's of others active on this matter as well, some of those are listed at the Tapiola's Control link page.
Text, drawings and photos are protected by copyright laws. Technical solutions, methods and source code are public domain only for non commercial purpose. All development has been carried out during our free time, mainly funded from our own pocket and with non selfish goals, so the use of this material for profitable use (including construction for a friend aginst a fee) is forbidden without written permit from the club. The pages contain errors, so, if you use the data given, you do so at your own risk and responsibility. If you further develop material found on these pages you must put it on display without fee e.g. to a freely available web page. We expect a note about this also.
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