Skip to main content

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/

Labels:

Comments

Post a Comment

Popular posts from this blog

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
Post a Comment
Read more

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...
Post a Comment
Read more

Audio signal processing IC for 1 5 V headphone stereo

General Description: The AN7500FHQ is a single chip IC optimum for a 1.5 V headphone stereo system including pre-amp., power amp. and Dolby B type noise reduction circuit. Current consumption in a Dolby circuit off mode has been drastically reduced and an operating supply voltage has also been lowered to 0.98 V. Much fewer external components  have been realized due to an integration of audio signal processing system into a single chip circuitry in a small outline package and space saving mounting of a set. Circuit Diagram Audio signal processing IC for 1.5 V headphone stereo
Post a Comment
Read more