Analoge Frequency Meter

[Dohani]

Gents,
I would like to get a brief sentences about the principle of operation :roll: of above subject device.

 

[Nigel Goodwin]

Gents,
I would like to get a brief sentences about the principle of operation :roll: of above subject device.

It's commonly done using a 555 in monostable mode, but you can also buy specific frequency to voltage chips.

 

[john1]

Hi Dohani,

I will try to use short sentences.
Maybe you are using a translate machine.
The most usual analogue frequency meters are for mains frequency.

If i wanted to make an analogue meter for 50c/s.
I would probably choose a centre-zero type of moving coil meter.

I would arrange inductors and capacitors like a bridge.

Over frequency would result in movement to the right.
Under frequency would result in movement to the left.

If you can rely on supply voltage.
Then cycles over and under centre could be marked.

48 ... 49 ..< 50 >.. 51 ... 52

(its 50 where i live, yours may be different)

The principles are simple,
but hard to explain with short sentences.
Inductors increase impedance with frequency.
Capacitors reduce impedance with frequency.

There is not much demand these days for
an analogue frequency meter.
Most stuff is digital.

Best of luck with it, John

 

[Ravi]

Hi dohani

Since you need to know the principle of operation, I would try to explain how it goes.Basically there are 3 stagesre-amp,Schmitt Triger & monostable.Usually pre-amp is wired as a non-inverting amp and function as a pre-amp for low level signal inputs.Many instances this is built around an op-amp of high input impedance,low bias current and good slew rate op-amp such as CA3140.Output of this is fed to a Schmitt triger.This output is a train of square waves at the same frequency as the input signal. This out put (coupled thro a cap.) trigers a monostable whose time duration is controlled by an external cap. and seclection of range resistors. The final output of monostable is given to an analog meter.In practice S.T & monostable are in a one IC such as NE556 dual timer.As John said there is no much of a demand now, for this type of test equipments.

Hope you understand.

 

[john1]

How do you delete ??

 

[john1]

Attempted to delete my posting,
because i didn't realise that this must refer to some
special analogue meter which is digital in its design
and probably uses an analogue display.

There must be other analogue frequency meters
apart from the mains frequency ones,
which normally have no digital element.

It was not clear to me that Dohani meant digital ones.
It is still not obvious.

 

[Klaus]

How do you delete ??

on the bottom of the message page it says what you can do with messages.
it says "you CANNOT delete your messages"

Forces you to think before hitting the 'submit' button :wink:

 

[Dohani]

Thank you all for your replies, and also I would especially thank Ravi for his explanation.
Yes I understood the principle and also if you could help me in how to search in the internet searching engines abut component function ( pre-amp, Schmitt trigger and monostable)

your reply will be appreciated.