Measurement of Inductance, Capacitance and some other quantities may be made conveniently and accuracy by A.C. Bridge circuits. The simple form of A.C. Bridge is very much resembles with D.C. Wheat – Stone Bridge. It consists of four arms. A power supply and a balance detector. The power source furnishes in Alternating current of 1, KHz in standard practice but in some cases measurements are also made on different frequencies.
The A.C. source is usually supplied by Audio Frequency Oscillator. A head – phone or a CRO also can be used for Null Detection but in sophiciated bridges an amplifier (Electronic Null Detector) is generally used which acts as Null Detector and Indications monitored on a moving coil Microampere Meter.
- For Capacitance
- For Resistance and Conductance
- For Inductance
- Schering Bridge
- Wien Bridge
- De – Sauty Bridge
- Maxwell Bridge
- Anderson Bridge
- Hay’s Bridge
- Owen Bridge
- Wheat – Stone Bridge
1. Anderson Bridge, Model – AB – 10.
The Anderson Bridge is usually used for measurement of Inductance in terms of Capacitance and Resistance. The actual circuit is printed on the panel. A builtin 1 KHz Since Wave Frequency Generator. Tuned frequency amplifier as Null detector and a moving coil Microamperemeter for Null indication & the Power Supply all are builtin. Thus these Bridges are self contained and also complete in all respects.Fitted with a pair of terminals. Marked “Phone / CRO” to be used with Headphone or C.R.O.
2. Maxwell Bridge, Model – MB – 10
The Maxwell Bridge is generally used for the measurement of low “Q” self Inductance for which “Hay” equation have awkward characteristics. It is not so desirable for high “Q” coils as it requires large values frequently inconveniently for R1 and does not give a sharp resistance unknown inductance. Null detector with builtin 1 KHz Oscillator. A digital meter for Null Detector and a D.C. Microamperemeter for Null Indication. The actual bridge and formula is given in operating instructions
3. Hay’s Bridge, Model – HB – 10
The Hay Bridge is different from the Maxwell Bridge only in having a resistance in series with the standard capacitor instead of in parallel with it for large phase angles this change requires a low series resistance instead of a very high parallel resistance. The Hay circuit gives more convenient values of resistance and better balancing for high “Q” inductance coils. The actual circuit and formula are engraved on panel, terminals are provided for connecting, headphone and high “Q” unknown inductance. The 1 KHz Oscillator and tuned amplifier fitted with Micro Ampere meter as Null Indicator and power supply are builtin.
4. Schering Bridge, Model–SB – 10
Schering Bridge is one of the most important A.C. Bridge. It is used in the measurement of capacitance in general. The Schering Bridge circuit is basically the same as capacitance comparison bridge. The basic circuit and formula are engraved on panel. Terminals are fitted for connecting headphone and unknown capacitance. The 1 KHz Oscillator and tuned amplifier with Micro Ampere Meter as Null Indicator and Power Supply are builtin.
5. Wheat – Stone Bridge, Model – WSB – 10.
The specialty of this bridge is that its measures resistance in wide range of DC or AC both. Terminals are provided to connect headphone and unknown resistance. 1 KHz Oscillator and tuned amplifier with Moving Coil Micro ampere Meter as a Null Indicator and power supply are builtin.
6. Wien Bridge, Model – WB – 10.
This bridge was used to a great extent in the past for the measurement of capacitance. The Wien Bridge is presented here primarily as frequency measuring device. This can give balance of one frequency only (variable frequency can not be used in this bridge). Therefore, it can be used to determine frequency and in fact has its chief application for this purpose. Terminals are provided to connect the power supply is builtin, headphone and unknown capacitance. The variable arm is linear variable calibrated resistance. Actual circuit and formula is engraved on panel. The 1 KHz Oscillator and tuned amplifier fitted with digital Meter as Null Indicator and power supply are builtin.
7. De – Sauty Bridge, Model – DSB – 10.
This Bridge was specially developed to measure capacitance having low ‘D’ factor. The 1 KHz Oscillator and tuned amplifier fitted with Moving Coil Micro Ampere Meter as Null Indicator and power supply are builtin.
8. Conductance Bridge:
The Conductivity and specific resistance of liquids and aqueous solutions is measured with conductance bridge. These measurements are possible only on A.C. Electrolyses phenomenon will take place if measured of D.C. The conductance bridge has many applications where chemical Technology place an important roll. The 1 KHz Oscillator and tuned amplifier fitted with Moving Coil Micro Ampere Meter as Null Indicator and Power Supply are builtin.
9. Owen Bridge,Model – OB – 10
The Owen Bridge is another circuit for the measurement of the inductance in terms of a standard capacitor. One arm consists of the standard capacitor only, and an adjacent arm consists a resistance and capacitance in series. The possibility of balancing the bridge is indicated by a study of a face angle of the arms. Arm No. ‘1’ has a capacity angle of 900 and ‘X’ and inductive angle less than 90 due to the presence of resistance, hence the some of this pair is slightly on the capacity side. Arm ‘2’ has an angle of 0, so balance may be secured if arm may be has a Capacitive angle equal to the difference of the angles of arms “1 and X”.
There may be any change in specification due to continuous R & D without notice.