Digital audio millivoltmeter by Silicon chip.

[thimios]

Has anyone assemble this?http://archive.siliconchip.com.au/cms/A_111191/article.html
Click on the block diagram(url) to see complete circuit diagram.
Thimios.

 

[Ian Finch]

Yes, I assembled it from a basic kit of the PCB, artwork and pre-programmed PIC. Given the sensitivity and bandwidth of the log. detector chip, you will lose signal in the noise also picked up - or at least you'll lose a lot of accuracy, with wiring like that of your breadboard, for an audio voltmeter.

I would buy the PCB and make certain it has a shielded (metal) case if you expect a decent instrument from your efforts. Otherwise, build something simple with a switched 2-pole attenuator followed by a low noise amplifier, precision rectifier and standard DVM module. Of course, there needs to be some frequency compensation with attenuators, so you may need to search the topic of Audio millivoltmeters for practical examples such as here: Audio Millivoltmeter

 

[thimios]

Yes, I assembled it from a basic kit of the PCB, artwork and pre-programmed PIC. Given the sensitivity and bandwidth of the log. detector chip, you will lose signal in the noise also picked up - or at least you'll lose a lot of accuracy, with wiring like that of your breadboard, for an audio voltmeter.

I would buy the PCB and make certain it has a shielded (metal) case if you expect a decent instrument from your efforts. Otherwise, build something simple with a switched 2-pole attenuator followed by a low noise amplifier, precision rectifier and standard DVM module. Of course, there needs to be some frequency compensation with attenuators, so you may need to search the topic of Audio millivoltmeters for practical examples such as here: Audio Millivoltmeter

This is the display stage, for programming test only!🙂
I burned my own pic and i want to know if this successfully occurred.
I will build the pcb for this and for inp.stage also.
Thanks for reply.
Thimios.

 

[Ian Finch]

It seems you have had complete success then! Good work and let's see your final results.
A suggestion though - build at least one decade of the switchable attenuator for the input.
It is just so easy to overload the 1.4V input level and either damage the input stage or
simply misread some types of signal.

 

[thimios]

It seems you have had complete success then! Good work and let's see your final results.
A suggestion though - build at least one decade of the switchable attenuator for the input.
It is just so easy to overload the 1.4V input level and either damage the input stage or
simply misread some types of signal.

Thanks my friend,i will come back if some parts will be arrived difficult finding for us in Greece.
Thimios.