"Oppie" wrote in message
.. .
"ian field" wrote in message
news
"Oppie" wrote in message
.. .
"ian field" wrote in message
...
Does anyone know the fancy/technical name for a model railway track
cleaner that's based on flyback pulses from a blocking oscillator to
break down oxide and crud on the rails?
Googling "model railway+track cleaner" produced a few examples of
commercial units but none were referred to by the technical name, I
need some schematic examples to base a similar gadget to clean switch
contacts in a 12V system that occasionally get corroded.
TIA.
Will this help you?
http://freespace.virgin.net/c.gardner/semg/relco.htm
also http://www.merg.org.uk/resources/faq.htm
Track cleaner A device for cleaning track so that dirt or other
deposits do not impede the flow of electric current. A number of methods
exist to accomplish this. MERG Technical Bulletin A4/1 features the
Relco Track Cleaner which superimposes a high frequency, high voltage
signal over the traction current. This burns through track deposits when
traction is interrupted. Mechanical abrasive rubber-type products are
also available such as the Peco PL41 Rail Cleaner and the MERG kit 83,
PCB and Track Cleaner. These must be rubbed over the track to clean it.
A variety of solvents applied with a clean cloth are also suitable as
are a number of wagon-mounted abrasive blocks. A popular MERG method is
to polish the rail tops with the rough surface of common hardboard.
July 2006
That's one of the pages I found googling and it doesn't mention the
technical name for an electronic track cleaner - I'll have to phone the
local model shop and ask them.
From what I can make of it, the device monitors the load and when it drops
out, superimposes HF pulses on top of the DC feed. Sounds similar to the
arc lamp ignitors I work with - a 20 turn winding in series with the DC
feed to the lamp (track) and a 2 turn primary fed by a spark gap
connected to a 600V charged capacitor. Spark gap breaks over and dumps
capacitor into primary. Nice sparks on the secondary!
Can't imagine this is too kind to any electronics installed in the layout
but then again, probably doesn't need the 14kv that my lamps need.
Happy Hunting
Oppie
That's more or less right, its based on a blocking oscillator with a winding
in series with the feed to the track. In a properly designed unit normal
current flow to the track causes the BO to stall and draw minimal current,
as soon as crud on the track breaks the circuit the BO starts and the high
voltage pulses burn the crud off.
A google search for "model train+track cleaner" didn't reveal the technical
name for the unit and I've phoned all the model shops in the local
directory, I've seen a circuit in one of the electronics magazines referred
to by the technical mane, but there's a lot of magazines to search through.