Precision Audio Millivoltmeter

Measures 10mV to 50Volt RMS in eight ranges
Simply connect to your Avo-meter set @ 50uA range
Circuit diagram

Parts:

R1 909K 1/2Watt 1% Metal Oxide Resistor
R2 90K9 1/2Watt 1% Metal Oxide Resistor
R3 9K09 1/2Watt 1% Metal Oxide Resistor
R4 1K01 1/2Watt 1% Metal Oxide Resistor
R5 100K 1/4W Resistor
R6 2M2 1/4W Resistor
R7 82K 1/4W Resistor
R8 12K 1/4W Resistor
R9 1K2 1/4W Resistor
R10 3K3 1/4W Resistor
R11 200R 1/2W Trimmer Cermet
C1 330nF 63V Polyester Capacitor
C2,C3 100uF 25V Electrolytic Capacitor
C4 220uF 25V Electrolytic Capacitor
C5 33pF 63V Polystyrene Capacitor
C6 2u2 63V Electrolytic Capacitor
D1-D4 1N4148 75V 150mA Diodes
IC1 CA3140 Op-amp
IC2 CA3130 Op-amp
SW1 2 poles 5 ways rotary switch
SW2 SPDT switch
J1 RCA audio input socket
J2,J3 4mm. output sockets
B1 9V PP3 Battery
Clip for PP3 Battery

Notes:

Connect J2 and J3 to an Avo-meter set @ 50uA range
Switching SW2 the four input ranges can be multiplied by 5
Total fsd ranges are: 10mV, 50mV, 100mV, 500mV, 1V, 5V, 10V, 50V
Set R11 to read 1V in the 1V range, with a sinewave input of 1V @ 1KHz
Compare the reading with that of another known precision Millivoltmeter or with an The oscilloscope reading must be a sinewave of 2.828V peak to peak amplitude
Frequency response is flat in the 20Hz-20KHz range
If you have difficulties in finding resistor values for R1, R2, R3 & R4, you can use the following trick:

R1 = 10M + 1M in parallel
R2 = 1M + 100K in parallel
R3 = 100K + 10K in parallel
R4 = 1K2 + 6K8 in parallel
All resistors 1% tolerance

Author: RED Free Circuit Designs
Source http://www.redcircuits.com/

Comments

Using the TLP250 Isolated MOSFET Driver Explanation and Example Circuits

I’ve already shown how to drive an N-channel MOSFET (or even an IGBT) in both high-side and low-side configurations in a multitude of ways. I’ve also explained the principles of driving the MOSFETs in these configurations. The dedicated drivers I’ve shown so far are the TC427 and IR2110. Some people have requested me to write up on MOSFET drive using the very popular TLP250. And I’ll explain that here. The TLP250, like any driver, has an input stage, an output stage and a power supply connection. What’s special about the TLP250 is that the TLP250 is an optically isolated driver, meaning that the input and output are “optically isolated”. The isolation is optical – the input stage is an LED and the receiving output stage is light sensitive (think “photodetector”). Before delving any further, let’s look at the pin configuration and the truth table. Fig. 1 - TLP250 Pin Configuration Fig. 2 - TLP250 Truth Table Fig. 1 clearly shows the input LED side and the receiving photodetector as well...

OP AMP INTEGRATOR CALCULATOR

Enter the Input Voltage,Vin: Volts Enter the Frequency, f: Hertz Enter the Input Resistance, Rin: Ohms Enter the Value of Capacitor, C: Farads Output Voltage, Vout: Volts OP AMP based Integrator Tutorial and Design

Block diagram of AM transmitter and receiver with explanation

Block diagram of AM transmitter and receiver with explanation AM Transmitter : Transmitters that transmit AM signals are known as AM transmitters. These transmitters are used in medium wave (MW) and short wave (SW) frequency bands for AM broadcast. The MW band has frequencies between 550 KHz and 1650 KHz, and the SW band has frequencies ranging from 3 MHz to 30 MHz. The two types of AM transmitters that are used based on their transmitting powers are: · High Level · Low Level High level transmitters use high level modulation, and low level transmitters use low level modulation. The choice between the two modulation schemes depends on the transmitting power of the AM transmitter. In broadcast transmitters, where the transmitting power may be of the order of kilowatts, high level modulation is employed. In low power transmitters, where only a few watts of transmitting power are required , low...

Do More

Search This Blog