GB2130849A

GB2130849A - Apparatus for delivering a signal on a telephone line

Info

Publication number: GB2130849A
Application number: GB08330313A
Authority: GB
Inventors: John Mary Walters
Original assignee: LAKE ELECTRONICS Ltd
Current assignee: LAKE ELECTRONICS Ltd
Priority date: 1982-11-17
Filing date: 1983-11-14
Publication date: 1984-06-06
Also published as: IE832743L; GB8330313D0; GB2130849B; HK6388A; IE54008B1; BE898246A

Abstract

Apparatus for delivering a signal to a telephone line to activate a telephone bell, comprises a transformer 3 which delivers a low voltage signal onto a telephone line 2 through a gate circuit 5. The gate circuit 6 is an opto-coupled triac integrated circuit. A control circuit 6 which comprises a microprocessor with a timing circuit, controls the gate circuit 5. The low voltage signal from the transformer secondary winding is also delivered to the control circuit 6. The gate allows certain time segments of the mains frequency waveform to pass thereby generating a lower frequency ringing signal. In a second embodiment, two out of phase components from the transformer are gated and added to provide a smoother low frequency signal (Figs. 4 and 5). <IMAGE>

Description

SPECIFICATION Apparatus for delivering a signal on a telephone line The present invention relates to apparatus for delivering a signal to activate an alerting device on a telephone instrument, for example, a bell.

In general, to activate the bell on a telephone instrument, a suitable AC signal is connected to the telephone line at the exchange. The frequency of this signal is normally in the range of 15 to 25 Hz. To obtain the AC signal, in general, a convertor is provided on the AC mains frequency or alternatively, a low frequency electronic oscillator may be used. Unfortunately, both convertors and oscillators require large heavy low frequency inductors and consequently are not suitable for miniaturised equipment.

Accordingly, there is need for apparatus for delivering a signal to activate an alerting device on a telephone instrument which will allow miniature equipment to be used.

The present invention is directed towards providing such apparatus for telephones and other relevant uses.

According to the invention, there is provided apparatus for delivering a signal to activate an alerting device on a telephone instrument, the apparatus comprising a transformer for delivering a signal through a gate circuit to a telephone line, a control circuit to control the gate circuit, and timing means for timing the control circuit.

In one embodiment of the invention, the transformer is fed from an AC source and delivers a low voltage signal onto the telephone line.

In another embodiment of the invention, the secondary winding of the transformer feeds the control circuit.

Preferably, the gate circuit comprises a solid state switch.

Advantageously, the solid state switch is an opto-coupled triac.

In a further embodiment of the invention, the control circuit is a dedicated timing circuit. Or aiternatively, it may be a microprocessor.

The invention will be more clearly understood from the following description of some preferred embodiments thereof given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a circuit diagram of apparatus according to the invention, Figs. 2 (a) to (c) are waveforms of output signals from the apparatus of Fig. 1, Figs. 3 (a) to (c) are waveforms of other output signals from the apparatus of Fig. 1, Fig. 4 is a circuit diagram of apparatus according to another embodiment of the invention, and Fig. 5 (a) to (e) are waveforms of output signals from the apparatus of Fig. 4.

Referring to the drawings, and initially to Fig. 1, there is illustrated a circuit diagram of apparatus according to the invention, indicated generally by the reference numeral 1, for delivering a signal onto a telephone line 2, to activate an altering device, for example, a bell on a telephone instrument (not shown). The apparatus 1 comprises a transformer 3 powered by a 50 to 60 Hz AC supply 4. The secondary winding of the transformer 3 is connected through a line 9 and a gate circuit 5 to the telephone line 2, and delivers a low voltage signal, in this case, 50 volts to activate the telephone bell. In this case, the gate circuit 5 is provided by an octo-coupled triac integrated circuit.

A control circuit 6 controls the gate circuit 5 through the line 7. The control circuit 6 in this case, is a microprocessor, the input of which is derived from the secondary winding of the transformer through the line 8. The microprocessor of the control circuit 6 also comprises a timing circuit for controlling the gate circuit 5.

In use, when the control circuit 6 activates the gate circuit 5, the transformer output signal is delivered onto the telephone line 2, and thus to the telephone apparatus. The control circuit output is synchronised with the mains voltage ar.d may be arranged in a number of different ways, which will be readily apparent to those skilled in the art. For example, referring to Fig. 2, the transformer voltage is illustrated by the waveform of Fig. 2 (a). The control output from the control circuit 6 is illustrated by Fig. 2 (b), and the output to the gate circuit 5 which is delivered onto the telephone line 2, is illustrated in Fig. 2 (c). In this case, the gate circuit is activated by the control circuit for one half cycle of the mains, and is turned off for the next two half cycles.The resultant output signal has a fundamental frequency of 50 - or 16.6 Hz.

3 Fig. 3 shows other waveforms from another arrangement. In this case, the gate circuit is activated and deactivated for alternate full cycles (the waveform of Fig. 3 (b)). Accordingly, the output signal from the gate of the telephone line 2 shown in Fig. 3 (c) has a fundamental frequency of 25 Hz.

Referring to Figs. 4 and 5, apparatus according to another embodiment of the invention is illustrated. In this case, two signals from the transformer 3 are delivered onto the telephone line 2. The signals from the transformer are 1800 out of phase, and are delivered on the lines 9 and 10 through gate circuits 5 and 15 respectively, onto the line 2. The gate circuit.5 is controlled by a control circuit 6, both similar to the gate circuit 5 and control circuit 6 of the apparatus described, with reference to Fig. 1. The gate circuit 1 5 on the line 10 is controlled by a control circuit 16, both of which are substantially similar to the gate circuit 5 and control circuit 6. The control circuit 1 6 derives its input through the line 1 8 from the output 10 of the transformer.

Fig. 5 (a) to (e) illustrates the waveforms of the apparatus. Waveforms (a) to (c) represent the outputs 9 and 10 from the transformer.

Waveforms (b) to (d) respectively illustrate the outputs from the controllers 6 and 1 6 on the lines 7 and 17. The resultant signal delivered onto the line 2 through the gate circuits 5 and 1 5 is illustrated by the waveform illustrated in Fig. 5 (e).

It will be appreciated that while two specific output signals from the apparatus have been described, many other suitable signals could be obtained without departing from the scope of the invention.

It is envisaged that in use, the transformer 3, the control circuit 6 and the gate circuit 5 will be housed in the exchange. Needless to say, it could be housed at any desired location.

It will of course be appreciated by those skilled in the art, that this apparatus according to the invention readily lends itself to miniaturisation.

It is also envisaged that the transformer may comprise other secondary windings or taps, for supplying other associated equipment.

Additionally, it will be appreciated that the microprocessor of the control circuit may also be used for other control purposes. Furthermore, it will be appreciated that while particular types of control circuits and gate circuits have been mentioned, other suitable circuits or apparatus could be used. Indeed, in certain cases it is envisaged that the control circuit may be provided by a dedicated timing circuit.

While the apparatus has been described for us in telephone circuitry, it will of course be appreciated that it could be used in many other uses.

Claims

1. Apparatus for delivering a signal to activate an alerting device on a telephone instrument, the apparatus comprising a transformer for delivering a signal through a gate circuit to a telephone line, a control circuit to control the gate circuit, and timing means for timing the control circuit.

2. Apparatus as claimed in Claim 1 in which the transformer is fed from an AC source and delivers a low voltage signal onto the telephone line.

3. Apparatus as claimed in Claim 1 or 2 in which the secondary winding of the transformer feeds the control circuit.

4. Apparatus as claimed in any preceding Claim in which the gate circuit comprises a solid state switch.

5. Apparatus as claimed in Claim 4 in which the solid state switch is an opto-coupled triac.

6. Apparatus as claimed in any preceding Claim in which the control circuit is a dedicated timing circuit.

7. Apparatus as claimed in any of Claims 1 to 5 in which the control circuit is a microprocessor.

8. Apparatus as claimed in any preceding Claim, in which the alerting device is a bell on a telephone instrument.

9. Apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.