TREVOR GIBBS MODEL RAILROAD PAGE

TREVOR GIBBS MODEL RAILROAD PAGE 8

MAIN	MODEL PAGE 2	MODEL CHASSIS	LATHE TURNING 1	LATHE TURNING 2
LATHE TURNING 3	OPERATING THE LAYOUT	Ersatz Ground Signals	TRANSISTOR THROTTLES I USE	SCALE SPEED

FURTHER PICTURES	OTHER PROJECTS	EXHIBITIONS	SIMPLE MODEL STREET LIGHTS	PASSES
SIMPLE CUTOUT BUILDINGS	BASIC SEARCHLIGHT SIGNALS	THE BUDDS!!!	NEW "CANADIAN" TREES!	THE GRAIN ELEVATOR
ST AGNES RAILWAY MAP	ONE OF MY TIMETABLES	MRE HINTS AND TIPS ***	NEW SIMPLE TO MAKE LQ SIGNALS

The Transistor Throttles...

Despite teaching Systems and Technology, I do not feel that I could hold a candle to many of my peers in the electronics field. The basis of this design came from an Australian Model Railway Magazine about 20 odd years ago. Although it was portrayed as an N scale throttle, I have had little problem using it for many of the locomotives I have had over the years although it does not like the higher current drawing motors such as Mantua's open frame types. It is based on a 2N3055 type transistor and I have built it as both a stand alone and as a walk around version.

You might like to change some of the values such as the capacitor and brake resistor for the inertia to suit as I like to have a fairly long braking sequence but in essence it should work well.

VR1 MAIN THROTTLE CONTROL	50 KILO OHM POTENTIOMETER
VR2 BRAKING CONTROL	200 KILO OHM POTENTIOMETER
VR3 & VR4 UPPER/LOWER SPEED CONTROLS	5 KILO OHM POTENTIOMETER
S1& S2	SINGLE POLE SINGLE THROW ON/OFF SW
S3 REVERSE SWITCH	DOUBLE POLE DOUBLE THROW SWITCH
C1 INERTIA CAPACITOR	1000 UF 30WV CAPACITOR
C2 FILTER CAPACITOR	470 UF 30WV CAPACITOR
C3 FILTER CAPACITOR	220 UF 40WV CAPACITOR
R1	560 OHM RESISTOR
R2	15K OHM RESISTOR
D1 AND D2	1N4004 DIODES
TR1	BFY50 NPN Transistor
TR2	2N3055 NPN TRANSISTOR
POWER SUPPLY	24-30 VOLTS DC 2 A preferable

HOW IT WORKS

The Main throttle VR1 is fed by two variable resistors VR3 and VR4. VR4 sets the Minimum speed of your throttle control while VR3 allows you to set your maximum speed.

C2 filters the control of your circuit but your supply to the track is unfiltered and maximises your motor performance. The Minimum speed provides a "bleed" of power to the inertia capacitor so your starting is fairly instantaneous. You should get a very good pulsing effect but ensure that you have capacitor C3 in place or you may be disappointed in the output

When your throttle is turned off, your inertia capacitor will take over and start discharging through the base of TR1 and the brake VR2.

The "Braking effort"/ coasting distance can be increased/decreased by turning VR2 and bringing the train to a stop earlier.

Some people I know substitute a Resistor for VR2 and a push button which could lead to an infinite slowdown time for the train... that is your choice!

Adjusting your throttle speeds

When first setting your throttle, turn your inertia switch (S1) OFF. Move your main throttle from its minimum speed setting about 60 degrees (I prefer to refer to it as 2 o'clock as I start with it in the 12 o'clock position) then adjust VR4 so that your light engine will just begin to move.

Then set your throttle to its maximum speed and use VR3 to set your throttles maximum speed or the desired maximum speed for your layout. This will enable you to use most of your throttle to control your train speed and provide a bit of insurance against those who want to run a train like a slot car! This is especially handy if you have a switching layout and want refined control

Aside from that enjoy...

Hope you enjoyed all this and please feel free to write if you need clarification

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