US3452682A - Model railway systems - Google Patents

Description

July 1, 1969 R. E. IRELAND 3,452,682

' MODEL RAILWAY SYSTEMS Filed Sept. 12, 1966 Sheet 3 of 2 IN ENTOI PEG/NHL!) ERNEST IRELGND United States Patent 3,452,682 MODEL RAILWAY SYSTEMS Reginald E. Ireland, 11 Farmway Close, Hove, England Filed Sept. 12, 1966, Ser. No. 578,828 Claims priority, application Great Britain, Sept. 14, 1965, 39,167/ 65 Int. Cl. A63h 19/10, 19/14 US. Cl. 104-150 Claims ABSTRACT OF THE DISCLOSURE This invention relates to model railway systems and it is an object of the invention to provide means for simulating the whistle or hooter of a locomotive.

From one aspect, the invention consists in a model railway system, including a direct-current power supply connected to the track for driving a locomotive thereon and an audio-frequency tone generator, the output of which is connected to the track, together with said power supply, to operate a sound-reproducing device.

From another aspect, the invention consists in a model railway system including a track, a direct-current power supply connected to said track, an audio-frequency tone generator the output of which is connected to said track, and a locomotive running on said track and driven by an electric motor connected by current-collecting means to said track, wherein said locomotive is provided with a sound-reproducing device coupled to said current-collecting means and responsive to audio-frequency current from said tone generator.

From another aspect, the invention consists in a model railway controller including a transistor amplifier, arranged to apply a direct current of variable magnitude to the railway track, and an audio-frequency tone generator, the output of which is connected to the input of said amplifier.

From yet another aspect, the invention consists in a model railway locomotive driven by a direct-current electric motor connected to means for collecting current from a track, wherein a sound-reproducing device is coupled to said current-collecting means through at least one capacitor.

One method of performing the invention will now be described with reference to the accompanying diagrammatic drawings, in which:

FIGURE 1 is a block diagram of a model railway system in accordance with the invention;

FIGURE 2 is a circuit diagram of a tone generator suitable for use in a system in accordance with the invention; and

FIGURE 3 is a circuit diagram of a model railway controller which may be used to apply the output of the tone generator illustrated in FIGURE 2 to the track of a model railway system in accordance with the invention.

In FIGURE 1, the lines 1 and 2 represent the currentcarrying members of a model railway track and the reference numeral 3 indicates a power control unit having output terminals 11 and 12 for supplying a direct current of variable magnitude to the lines 1 and 2. In accordance with the invention, the unit 3 includes means for gener- 3,452,682 Patented July 1, 1969 ICC ating an audio-frequency signal which is applied to the lines 1 and 2 in parallel with the variable magnitude direct current.

The reference numeral 4 indicates a model railway locomotive having current-collecting means 5 and -6 in contact with the lines 1 and 2. The current-carrying means 5 and 6 are connected to the terminals of an electric motor 7 which is arranged to drive the locomotive 4. The current collectors 5 and 6 are also connected through capacitors 8 and 9 t0 the input terminals of a sound-reproducing device 10. This device may be of any kind which is responsive to the audio-frequency signal applied to the track by the unit 3 and which is small enough to fit into the locomotive concerned. It has been found that, particularly with small-scale models, a balanced armature microphone capsule constitutes a suitable sound-reproducing device.

The circuit arrangement illustrated in FIGURE 2 includes two p-n-p type transistors TR1 and TR2 connected in a conventional multi-vibrator circuit. The power supply for the tone generator may, for example, be constituted by the same power source as is used for driving the locomotive and is connected to the terminals 21 and 22. The voltage of this power supply will normally be between 12 and 15 volts. The power supply is smoothed by means of a resistor 20 and an electrolytic capacitor 23.

The emitters of the two transistors TR1 and TR2 are connected to the positive terminal 22 of the power supply and their collectors are connected through respective resistors 24 and 25 to the junction of the resistor 20 and the capacitor 23. The base electrodes of the two transistors are connected to their respective collectors through respective resistors 26 and 27, the value of the resistor 27 being approximately twice that of the resistor 26. Further, the collector of the transistor TR1 is connected to an output terminal X and is coupled to the base electrode of the transistor TR2 through a capacitor 28. The collector of the transistor TR2 is capable of being coupled to the base electrode of the transistor TR1 through one or both of a pair of capacitors 29 and 30. Two push-button switches A and B are provided to connect in circuit the capacitors 30 and 29, respectively. In one particular embodiment, the capacitor 30 has a value of 0.1 microfarad and the capacitor 29 has a value of 0.02 microfarad. In this case, closing the switch A causes the generator to produce a signal at the output terminal X which simulates the frequency spectrum of a diesel hooter, whereas closure of the switch B causes the generator to produce a signal which simulates the frequency spectrum of a steam whistle.

The control unit illustrated in FIGURE 3 includes three p-n-p type transistors TR3, TR4 and TR5 connected as a direct-coupled D.C. amplifier. The power supply for the control unit is connected to terminals 31 and 32 and again may, for example, operate at a voltage between 12 and 15 volts. The output terminals 11 and 12 of the unit are connected respectively to the emitter of the transistor TR5 and the positive terminal 32 of the power supply. The collectors of the three transistors are connected to the negative terminal 31 While the emitter of the transistor TR3 is connected to the base electrode of the transistor TR4 and the emitter of the transistor TR4 is connected to the base electrode of the transistor TR5. Thus, variation of the current supplied to the base electrode of the transistor TR3 controls the collector currents of all three transistors and hence the current supplied to the track.

The main control for the base current of the transistor TR3 is constituted by a potentiometer 33, the winding of which is connected between the terminals 31 and 32. The wiper of this potentiometer is connected through a resistor 34 and a rectifier 35 connected in parallel, a

resistor 36, a switch SlA and a resistor 37 to the base electrode of the transistor TR3, which is also connected to the positive terminal of the supply through a resistor 46. The junction between the switch SlA and the resistor 37 is connected through an electrolytic capacitor 38 to the terminal 32.

The switch S1A has a movable arm 39 and six fixed contacts arranged to give the switch six operative positions. When the switch is in the first operative position, as illustrated in the drawing, the current supplied to the base electrode of the transistor TR3 is determined by the potentiometer 33, as already described. In the second position of the switch, the end of the resistor 37 remote from the transistor TR3 is connected solely to the capacitor 38 and hence the current supplied to the base electrode of the transistor TR3 is determined solely by the charge on the capacitor 38.

In the third operative position of the switch, the arm 39 is connected through three series resistors 40, 41 and 42 to the terminal 32. Thus, under these conditions, the discharge rate of the capacitor 38 is determined by the total value of these three resistors. In the fourth position, the capacitor discharge rate is determined by the sum of the resistances of the resistors 41 and 42, whereas in the fifth position the discharge rate is determined solely by the value of the resistor 42. In the sixth position the arm 39 is open-circuited, as in the case of the second position.

A switch S1 is ganged to the switch 81A and is similarly provided with a movable arm 43 and six fixed contacts, giving six operational positions. In the first operational position, the wiper of the potentiometer 33 is connected through a capacitor 54 and a resistor 45 to the base electrode of the transistor TR3. In the second, third, fourth and fifth operational positions, the arm 43 is open-circuited, whereas in the sixth operational position it is connected to the wiper of a further potentiometer 44, the winding of which is connected in parallel with the winding of the main speed control potentiometer 33. The wipers of the two potentiometers 33 and 44 are connected through individual resistOr 47 and 48 to one terminal 49 of an alternating current source, the other terminal of which is connected to the terminal 32.

When the control unit is in use, the train is started for normal running by putting the switches S1 and S1A into the position shown in the drawing with the wiper of the potentiometer 33 at the positive end of the potentiometer winding. Movement of the wiper towards the negative end of the winding charges the capacitor 38 through the rectifier 35 and the relatively low value resistor 36. As the charge on the capacitor is increased, current is supplied to the base electrode of the transistor TR3 and all the transistors commence to conduct. At the same time, an alternating-current signal from the terminal 49 is supplied through the resistor 47, the capacitor 54 and the resistor 45, direct to the base electrode of the transistor TR3. As a result, pulses of current are applied to the track to overcome the inertia of the locomotive and to counteract the eifects of friction when the direct current is low. If the wiper of the potentiometer 33 is moved back towards the positive end of the winding, the rectifier 35 ceases to conduct and the capacitor 38 discharges through two parallel paths, one of which is constituted by the resistor 37, the base emitter paths of the three transistors and the load, and the other of which is constituted by the resistors 36 and 34 and the lower end of the winding of the potentiometer 33. Thus, the rectifier 35 is operative to enable the current supplied to the track to be increased more quickly than it can be decreased, to simulate acceleration.

When the switches S1 and SlA are moved to their second positions, the capacitor 38 discharges solely through the load and the high value resistor 46. This position therefore simulates coasting of the train. As the switches are moved round to their third, fourth and fifth positions, the rate of discharge of the capacitor 38 is increased to simulate increasing application of the brakes. When the switches are moved to their final position, control of the speed of the train is effected by means of the potentiometer 44 instead of the potentiometer 33 and in this case variation of the base current of the transistor TR3 is obtained substantially instantaneously, since the value of the resistor 45 is very much lower than the value of the resistor 37, so that the capacitor 38 is substantially ineffective. Further, with the switches in this position the alternating current from the terminal 49 is supplied to the base electrode of the transistor TR3 ata higher amplitude than when the switches are in the position illustrated in the drawing. Thus, under these conditions, the train can be run at very low speeds, since the alternating current overcomes the effects of friction and inertia. This position is therefore normally used for shunting operations since it gives very fast and accurate control over the speed of the train. In this connection, it must be pointed out that the terminals 11 and 12 are normally connected to the track through a reversing switch to enable the sense of the current, and hence the direction of travel, to be reversed.

In accordance with the invention, the output terminal X of the tone generator illustrated in FIGURE 2 is connected to the terminal X shown in FIGURE 3 connected to the base electrode of the transistor TR3. Thus, when either of the push-button switches A or B is closed, an audio-frequency signal is applied to the transistor TR3 and is amplified by the chain of three transistors. Thus, an amplified version of the audio-frequency signal appears at the terminals 11 and 12 and reaches the sound-reproducing device 10 through the lines 1 and 2, the currentcollecting devices 5 and 6 and the capacitors 8 and 9. Accordingly, operation of the hooter of a diesel locomotive or the whistle of a steam locomotive can be simulated by pressing the appropriate button.

Although in the embodiment described the output of the tone generator is applied to the track through he amplifier used for controlling the locomotive direct current, it is to be understood that a separate amplifier may be used, if desired. In this case, it is preferable that the output of the separate amplifier should be applied to the track through isolating capacitors of similar value to the capacitors 8 and 9 used in the locomotive. It is also to be understood that where current-collecting means are provided in the train for purposes other than driving the locomotive, for example, for operating lighting in carriages, the sound-reproducing device may be located in any part of the train where a connection to the track is available, but in any such case it will normally be desirable to provide the isolating capacitors 8 and 9 in order to isolate the sound-reproducing device from the direct current which might cause damage to the device.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A model railway system including a track, a locomotive running on said track, said locomotive including an electric motor connected by current-collecting means to said track, said locomotive being provided with a sound-reproducing device coupled to said current-collecting means and responsive to audio-frequency current, a direct current power supply connected to said track and including a controller having amplifier means the output of which is connected with said track, said controller being arranged to apply a variable current through said amplifier means to the track, an audio-frequency tone generator, and means connecting the output of said tone generator to said track.

2. Apparatus as defined in claim 1 wherein the output of said audio-frequency tone generator is connected to the input of said amplifier means.

3. Apparatus as defined in claim 1 wherein said tone generator comprises a multivibrator.

4. Apparatus as defined in claim 1 wherein said amplifier means includes a plurality of direct-coupled transistors, and wherein the output of said tone generator is con- 5 nected directly to the base electrode of one of said transistors.

5. Apparatus as defined in claim 1 wherein said tone generator is an asymmetrical transistor multivibrator.

6. Apparatus as defined in claim 1 wherein said controller includes switch means for applying pulses of current to said track.

7. Apparatus as defined in claim 6 wherein the controller includes rectifier means to enable the current supply to the track to be increased more quickly than it can be decreased to simulate acceleration.

8. Apparatus as defined in claim 6 wherein said switch means includes an operative position for simulating the coasting of the train.

9. Apparatus as defined in claim 6 wherein said switch means includes an operative position for simulating increasing application of the brakes of the train.

10. Apparatus as defined in claim 1 wherein said tone generator is a multivibrator, and including means for selectively varying the frequency of the output of said tone generator so that a first tone applied to said s0undreproducing device simulates a steam-engine whistle and a second tone applied to said sound-reproducing device simulates a diesel-engine hooter.

References Cited UNITED STATES PATENTS 2,622,542 12/1952 Bonanno 104-150 2,714,859 8/1955 Klemme 104-150 2,965,044 12/1960 Johnson 104-150 3,341,842 9/1967 Breguet 104150 XR ARTHUR L. LA POINT, Primary Examiner.

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