GB2206749A - A voltage adaptor - Google Patents

A voltage adaptor Download PDF

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Publication number
GB2206749A
GB2206749A GB08716104A GB8716104A GB2206749A GB 2206749 A GB2206749 A GB 2206749A GB 08716104 A GB08716104 A GB 08716104A GB 8716104 A GB8716104 A GB 8716104A GB 2206749 A GB2206749 A GB 2206749A
Authority
GB
United Kingdom
Prior art keywords
voltage
adaptor
output
transformerless
diode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08716104A
Other versions
GB8716104D0 (en
Inventor
Kar Duk Lam
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sealand Ind Co Ltd
Original Assignee
Sealand Ind Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sealand Ind Co Ltd filed Critical Sealand Ind Co Ltd
Priority to GB08716104A priority Critical patent/GB2206749A/en
Publication of GB8716104D0 publication Critical patent/GB8716104D0/en
Publication of GB2206749A publication Critical patent/GB2206749A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/05—Capacitor coupled rectifiers

Abstract

A transformerless voltage adaptor has an input for an AC voltage supply and an output for supplying a substantially constant DC voltage. The adaptor incorporates a diode bridge (D1) and a smoothing capacitor (C2) at the output of the diode bridge for converting the AC supply voltage into the DC voltage. A capacitor-resistor parallel circuit (C1,R1) is provided at the input of the diode bridge for reducing the voltage applied thereto. To limit the output voltage of the adaptor to a substantially constant value, a series diode circuit (D2-D11) is provided across the adaptor output terminals. <IMAGE>

Description

A VOLTAGE ADAPTOR The present invention relates to a voltage adaptor.
It is known to provide a voltage adaptor incorporating a step-down voltage transformer to convert a mains or high AC voltage into a low DC voltage for supplying power to an electrical appliance. However the transformer introduces excessive weight and size to the adaptor.
The present invention seeks to mitigate such shortcoming by providing a voltage adaptor incorporating no transformer.
Thus according to the invention there is provided a voltage adaptor having an input for an AC voltage supply and an output for supplying a substantially constant DC voltage , rectifier means, and a smoothing capacitor for smoothing the output of the rectifier means, wherein there is provided impedance means for reducing the voltage supplied from the input to the rectifier means, and diode means for limiting the output voltage of the adaptor to a substantially constant value.
Preferably, the diode means comprise a diode or a series circuit of diodes connected between the output terminals of the adaptor.
Preferably, the impedance means comprise a parallel capacitor-resistor circuit in series connection with the rectifier means.
Advantageously, an overload protection fuse is provided in series connection with one input terminal of the rectifier means.
More advantageously, signal means comprising a light emitting diode are provided in circuit connection with the output of the adaptor to indicate the presence of an output voltage at the adaptor output.
The present invention will now be more particularly described, by way of example, with reference to the accompanying drawing, which shows the circuit diagram of a transformerless voltage adaptor embodying the invention.
The transformerless voltage adaptor shown in the drawing comprises an input for an AC voltage supply and an output for supplying a substantially constant DC voltage.
Rectifier means D1 in the form of a solid state diode bridge is provided whose AC input terminals are respectively connected via an overload protection fuse F in series connection with a parallel circuit of a resistor R1 and a capacitor C1, and directly to the input terminals of the voltage adaptor. The cathode and anode of the rectifier D1 function respectively as the positive and negative output terminals of the voltage adaptor.
A capacitor C2, a series circuit of a resistor R2 and a light emitting diode LED, and a series circuit of ten solid state silicon diodes D2 to D11 are respectively connected between the output terminals of the voltage adaptor.
The anode and cathode of the series diode circuit, which is formed by connecting the anodes and cathodes of succeeding diodes D2 to Dll, are respectively connected to the positive and negative output terminals of the voltage adaptor.
In use, an AC supply voltage is applied to the input terminals of the voltage adaptor. The parallel circuit of the resistor R1 and capacitor C1 functions as a series input impedance to the rectifier means D1 for reducing the voltage applied thereto, the resistor R1 providing the capacitor C1 with a discharging path.
The rectifier means D1 outputs a pulsating DC voltage whose magnitude is smaller than that of the AC supply voltage. The pulsating DC voltage is then smoothed by the smoothing capacitor C2.
The voltage drop across a solid state silicon diode, when in a forward conducting state, is substantially 0.75V.
Therefore, the series circuit of diodes D2 to D11 maintains a substantially constant DC voltage of 7.5V between its terminals or the output terminals of the voltage adaptor when the DC output voltage of the rectifier means 10 applied to the series diode circuit exceeds 7.5V.
Alternatively, a 7.5V zener diode may be used in place of the series diode circuit. In this case, the zener diode should be connected in a reverse bias direction so that avalanche breakdown may occur in the zener diode to maintain the output voltage of the voltage adaptor at a substantially constant value.
The light emitting diode LED signals the presence of an output voltage of the voltage adaptor, and the resistor R2 limits the magnitude of the current flowing through the light emitting diode LED.
The normal output voltage of the voltage adaptor is determined by the potential difference appearing at the two terminals of the series diode circuit D2 to D11 when in a forward conducting state. Hence provided that the output voltage of the rectifier means 10 appearing at the two terminals of the smoothing capacitor C2 at all time exceeds the normal adaptor output voltage, the latter remains substantially constant independent of any small fluctuation in the AC supply voltage. It is clear from above that the output voltage and current ratings of the voltage adaptor can be modified by using a capacitor C1 of different capacitance value and by using a different number of diodes in the series diode circuit.
Various modifications and alterations to the voltage adaptor would be apparent to those skilled in the art and it is intended to include all such modifications and alterations as fall within the scope of the appended claims.

Claims (6)

1. A transformerless voltage adaptor having an input for an AC voltage supply and an output for supplying a substantially constant DC voltage, rectifier means, and a smoothing capacitor for smoothing the output of the rectifier means, wherein there is provided impedance means for reducing the voltage supplied from the input to the rectifier means, and diode means for limiting the output voltage of the adaptor to a substantially constant value.
2. A transformerless voltage adaptor as claimed in claim l, wherein said diode means comprise a diode or a series circuit of diodes connected between the output terminals of the adaptor.
3. A transformerless voltage adaptor as claimed in claim 1 or claim 2, wherein said impedance means comprise a parallel capacitor-resistor circuit in series connection with the rectifier means.
4. A transformerless voltage adaptor as claimed in any one of the preceding claims, wherein an overload protection fuse is provided in series connection with one input terminal of said rectifier means.
5. A transformerless voltage adaptor as claimed in any one of the preceding claims, wherein signal means are provided in circuit connection with the output of the adaptor to indicate the presence of an output voltage at the adaptor output.
6. A transformerless voltage adaptor substantially as hereinbefore described with reference to the accompanying drawing.
6. A transformerless voltage adaptor as claimed in claim 5, wherein said signal means comprise a light emitting diode in series connection with d resistor.
7. A transformerless voltage adaptor substantially as hereinbefore described with reference to the accompanying drawing.
Amendments to the claims have been filed as follows CLAIMS 1. A transformerless voltage adaptor having an input for an AC voltage supply and an output for supplying a substantially constant DC voltage, rectifier means and a smoothing capacitor for smoothing the output of the rectifier means, wherein there is provided impedance means for reducing the voltage supplied from the input to the rectifier means, and at least one diode connected across the output to be forward biassed and in parallel to a load connected to the output, the output voltage of the adaptor being determined by the voltage drop across the at least one diode.
2. A transformerless voltage adaptor as claimed in claim 1, wherein said impedance means comprise a parallel capacitor-resistor circuit in series connection with the rectifier means.
3. A transformerless voltage adaptor as claimed in claim 1 or 2, wherein an overload protection fuse is provided in series connection with one input terminal of said rectifier means.
4. A transformerless voltage adaptor as claimed in claim l, 2 or 3, wherein signal means are provided in circuit connection with the output of the adaptor to indicate the presence of an output voltage at the adaptor output.
5. A transformerless voltage adaptor as claimed in claim 4, wherein said signal means comprise a light emitting diode in series connection with a resistor.
GB08716104A 1987-07-08 1987-07-08 A voltage adaptor Withdrawn GB2206749A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08716104A GB2206749A (en) 1987-07-08 1987-07-08 A voltage adaptor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08716104A GB2206749A (en) 1987-07-08 1987-07-08 A voltage adaptor

Publications (2)

Publication Number Publication Date
GB8716104D0 GB8716104D0 (en) 1987-08-12
GB2206749A true GB2206749A (en) 1989-01-11

Family

ID=10620325

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08716104A Withdrawn GB2206749A (en) 1987-07-08 1987-07-08 A voltage adaptor

Country Status (1)

Country Link
GB (1) GB2206749A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2357162B (en) * 1999-11-30 2004-04-07 Gtc Properties Inc Transformerless quartz analog clock

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1088210A (en) * 1963-12-26 1967-10-25 Sperry Rand Corp Electrical appliance with a power control circuit
GB1420387A (en) * 1972-04-01 1976-01-07 Semikron Gleichrichterbau Overvoltage limiting circuit arrangement
US3978388A (en) * 1973-07-13 1976-08-31 Zellweger Uster Ltd. Current-supply arrangement for an electronic remote control receiver
GB1532677A (en) * 1975-10-09 1978-11-15 Indesit Voltage dropping circuit
GB1574078A (en) * 1976-12-01 1980-09-03 Telefonbau & Normalzeit Gmbh Voltage-limiting circuit
GB1599757A (en) * 1977-02-04 1981-10-07 Tronicair Int Ltd Voltage converter
EP0098647A1 (en) * 1982-07-02 1984-01-18 Koninklijke Philips Electronics N.V. Mains-voltage discrimination device
GB2136643A (en) * 1983-03-17 1984-09-19 Diehl Gmbh & Co A transformerless power pack

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1088210A (en) * 1963-12-26 1967-10-25 Sperry Rand Corp Electrical appliance with a power control circuit
GB1420387A (en) * 1972-04-01 1976-01-07 Semikron Gleichrichterbau Overvoltage limiting circuit arrangement
US3978388A (en) * 1973-07-13 1976-08-31 Zellweger Uster Ltd. Current-supply arrangement for an electronic remote control receiver
GB1532677A (en) * 1975-10-09 1978-11-15 Indesit Voltage dropping circuit
GB1574078A (en) * 1976-12-01 1980-09-03 Telefonbau & Normalzeit Gmbh Voltage-limiting circuit
GB1599757A (en) * 1977-02-04 1981-10-07 Tronicair Int Ltd Voltage converter
EP0098647A1 (en) * 1982-07-02 1984-01-18 Koninklijke Philips Electronics N.V. Mains-voltage discrimination device
GB2136643A (en) * 1983-03-17 1984-09-19 Diehl Gmbh & Co A transformerless power pack

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2357162B (en) * 1999-11-30 2004-04-07 Gtc Properties Inc Transformerless quartz analog clock

Also Published As

Publication number Publication date
GB8716104D0 (en) 1987-08-12

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)