Radio, 1998, 1
Ac Voltmeter Using Half Wave Rectifier Diagram
In either case the current that flows through the meter is the rectified alternating current. In case of half wave rectifier the equivalent d.c value of the rectified alternating voltage will be. Edc = 0.45 x ERMS. In the case of full wave rectifier the equivalent d.c value of rectified alternating voltage will be. If a Half wave rectifier is connected ahead of DC voltmeter, then that entire combination together is called AC voltmeter using Half wave rectifier. The block diagram of AC voltmeter using Half wave rectifier is shown in below figure. The above block diagram consists of two blocks: half wave rectifier and DC voltmeter. We will get the corresponding circuit diagram, just by replacing each block with the respective component(s) in above block diagram. So, the circuit diagram of AC voltmeter. The rectifier can be used before the multistage amplifier or after the amplifier. This depends on the type of amplifier used in AC voltmeter. If we are using multistage AC amplifier, then the rectifier circuit will be used after the amplifier. On the contrary, if the multistage amplifier used is DC, then the rectifier should be used before it. In the half-wave AC/DC converter in Figure 5, the circuit gives a voltage gain of x2.22 via R2/R1, to give form-factor correction, and integration is accomplished via C1-R2. Note that this circuit has a high output impedance, and the output must be buffered if it is to be fed to low-impedance loads. Precision full-wave AC/DC converter. The half wave rectifier utilizes alternate half cycles of the input sinusoid. Figure 1 shows the circuit of a half-wave rectifier circuit. Voltage to be rectified is applied to the input of the transformer and the voltage v i across the secondary is applied to the rectifier.
The linearity of the scale of a simple AC voltmeter can be improved by using half-wave transistor rectifier with (Fig. 1). The proposed circuits are designed as a modification of the voltmeter described in 'Radio', 1985, № 11.
Fig. 1.
VT1 - germanium USSR transistor GT310G (Transition frequency (ft) = 160MHz; Forward current transfer ratio (hFE) = 60..180);
VD1 - silicon diode KD522A;
PA1 - microammeter with full scale deflection of 50 uA
The device uses a microammeter with full scale deflection of 50 uA and with the resistance of 2 kilohms. Gopro studio 64 bit per mac. The upper limit of the measuring range of the voltmeter is 1 V, and in the range of 0.2..1 V the measurement error due to the nonlinearity of the scale is less than 1% of the full scale range.
By selection of the resistor R3 values the voltmeter is calibrated at the middle of the scale, and by selection of the resistor R1 values - in the end of the scale. The linearization of the right side of the scale achieved due to the base current, which creates a voltage drop across the resistor R2. Because of this the gain of the rectifier are reduced to the end of the scale as required.
If the measurement range is 3..5 Volts and above, then it is better to use a silicon transistor in the rectifier. This voltmeter for the range of 10 V with the transistor KT3102D, has an error due to the nonlinearity of the scale at range of 1 V about 2%, and in the range of 2..10 V - less than 0.1% of the full scale range. Parameters of the circuit components are: R1 - 20 kilohm, R2 - 180 kilohms, and R3 - 62 kilohms.
A voltmeter with a full-wave rectifier can be implemented with transistors of the same p-n-p type as shown in Fig. 2. The resistance of the resistors R4, R6 is roughly determined from the relation: R < Un/2In, where Un - the measurement range, and In - the full scale deflection current of the microammeter.
Fig. 2.
VT1 - germanium USSR transistor GT310G (Transition frequency (ft) = 160MHz; Forward current transfer ratio (hFE) = 60..180);
The input impedance of this voltmeter is greater than the input impedance of the bridge circuit with the four transistors, because the measured network is loaded with two resistors in the bases of the transistors, rather than four resistors. Also the two transistors of the same structure is easier to find.
Ac Voltmeter Diy
It is possible to extend the limits of measurement by using an additional voltage divider, that provides the current much more than the base current. The use of additional resistors shifting the balance achieved in the calibration, and the linearity of the scale gets worse.
Ac Voltmeter Using Half Wave Rectifier Power Supply
Ac Voltmeter Using Half Wave Rectifier Diagram
In either case the current that flows through the meter is the rectified alternating current. In case of half wave rectifier the equivalent d.c value of the rectified alternating voltage will be. Edc = 0.45 x ERMS. In the case of full wave rectifier the equivalent d.c value of rectified alternating voltage will be. If a Half wave rectifier is connected ahead of DC voltmeter, then that entire combination together is called AC voltmeter using Half wave rectifier. The block diagram of AC voltmeter using Half wave rectifier is shown in below figure. The above block diagram consists of two blocks: half wave rectifier and DC voltmeter. We will get the corresponding circuit diagram, just by replacing each block with the respective component(s) in above block diagram. So, the circuit diagram of AC voltmeter. The rectifier can be used before the multistage amplifier or after the amplifier. This depends on the type of amplifier used in AC voltmeter. If we are using multistage AC amplifier, then the rectifier circuit will be used after the amplifier. On the contrary, if the multistage amplifier used is DC, then the rectifier should be used before it. In the half-wave AC/DC converter in Figure 5, the circuit gives a voltage gain of x2.22 via R2/R1, to give form-factor correction, and integration is accomplished via C1-R2. Note that this circuit has a high output impedance, and the output must be buffered if it is to be fed to low-impedance loads. Precision full-wave AC/DC converter. The half wave rectifier utilizes alternate half cycles of the input sinusoid. Figure 1 shows the circuit of a half-wave rectifier circuit. Voltage to be rectified is applied to the input of the transformer and the voltage v i across the secondary is applied to the rectifier.
The linearity of the scale of a simple AC voltmeter can be improved by using half-wave transistor rectifier with (Fig. 1). The proposed circuits are designed as a modification of the voltmeter described in 'Radio', 1985, № 11.
Fig. 1.
VT1 - germanium USSR transistor GT310G (Transition frequency (ft) = 160MHz; Forward current transfer ratio (hFE) = 60..180);
VD1 - silicon diode KD522A;
PA1 - microammeter with full scale deflection of 50 uA
The device uses a microammeter with full scale deflection of 50 uA and with the resistance of 2 kilohms. Gopro studio 64 bit per mac. The upper limit of the measuring range of the voltmeter is 1 V, and in the range of 0.2..1 V the measurement error due to the nonlinearity of the scale is less than 1% of the full scale range.
By selection of the resistor R3 values the voltmeter is calibrated at the middle of the scale, and by selection of the resistor R1 values - in the end of the scale. The linearization of the right side of the scale achieved due to the base current, which creates a voltage drop across the resistor R2. Because of this the gain of the rectifier are reduced to the end of the scale as required.
If the measurement range is 3..5 Volts and above, then it is better to use a silicon transistor in the rectifier. This voltmeter for the range of 10 V with the transistor KT3102D, has an error due to the nonlinearity of the scale at range of 1 V about 2%, and in the range of 2..10 V - less than 0.1% of the full scale range. Parameters of the circuit components are: R1 - 20 kilohm, R2 - 180 kilohms, and R3 - 62 kilohms.
A voltmeter with a full-wave rectifier can be implemented with transistors of the same p-n-p type as shown in Fig. 2. The resistance of the resistors R4, R6 is roughly determined from the relation: R < Un/2In, where Un - the measurement range, and In - the full scale deflection current of the microammeter.
Fig. 2.
VT1 - germanium USSR transistor GT310G (Transition frequency (ft) = 160MHz; Forward current transfer ratio (hFE) = 60..180);
The input impedance of this voltmeter is greater than the input impedance of the bridge circuit with the four transistors, because the measured network is loaded with two resistors in the bases of the transistors, rather than four resistors. Also the two transistors of the same structure is easier to find.
Ac Voltmeter Diy
It is possible to extend the limits of measurement by using an additional voltage divider, that provides the current much more than the base current. The use of additional resistors shifting the balance achieved in the calibration, and the linearity of the scale gets worse.
Ac Voltmeter Using Half Wave Rectifier Power Supply
Ac Voltmeter Using Half Wave Rectifier Circuits
V. KHVALYNSKY
Full Wave Rectifier
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