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condenser and electret mics

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simonwai999

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polarity of mic condenser

hi
i wanna make this clap switch
but i only have a condenser mic
can i use it instead of using the electret mic in the circuit?


thanks a lot

Added after 5 hours 53 minutes:

HI


reporting
i built this with a condenser mic
and the result is weird
it says it is on when i clap once
then it turns it off when i clap again
the result is diff
i clap and it turn on and it stays on for a very short time and it goes off automatically
( i cannot clap to turn it off)
then i can clap to turn it on again hmmmmmmmmmmmm the same process continues


here is the link

**broken link removed**
can any smart fellows in this forum clear my doubts?
Thanks a lot

Ps: I connected exactly like the circuit
 

two wire prepolarized condenser

You apparently managed to turn the bistable circuit into an astable one. This is very unlikely a matter of the connected mirophone, it raises doubts that your post's last sentence may be erroneous.
 

testing a condenser electret mic

hi pal

i do not quite understand
what do you mean by my last wrong sentence?
i really followed this circuit

in every details
except i used a condenser mic

one more thing is the circuit using bistable ?
Thanks
 

electret mics too sensitive

Are you sure that it is not an electret mic that you have. Condenser are usually high quality studio type microphones used in recording and broadcasting. These require a polarizing voltage to operate. Electrets on the other hand are usually cheap units found in consumer electronics. The only real difference is that electrets have a plastic diaphram that is polarized during manufacture, they therefore do not need a polarizing voltage to work. However these usually have a built in Fet amp that needs a typical 1.5v for correct operation. Condenser mics need a much greater voltage than this, but produce a much lower output that electrets. Therefor the two are not really interchangeable. I hope this gives you a clearer idea of how these work, but of course it may not solve your immediate problem
 

48v to 1.5v circuit electret

Yes, I meant that you apparently built a somewhat different circuit. The original is actually bistable, a two-transistor flip-flop. A flip-flop doesn't change the state without an input pulse.

I thought basically the same regarding your so-called condenser microphone, but as I said, I think it's not related to the reported problem.
 

2 transistor electret mic amplifier

hi folks
thanks for your help
i bought this so called condenser mic from a local electronics shop
it stated it is a condenser mic
and
after i read what grand said
my mic is a condenser mic for sure
coz when i reversed the 2 pins it did not work
it has its polarity

so the circuit on that site cannot change states
and it is wrong from what it says on the website that
clap once it is on and clap again it is off then since it is a bistable type

thanks
 

A "condenser" mic is very old. They need about 48V to bias them. A modern electret mic has the 48V bias voltage built-in.
Some shops call a modern electret mic a condenser mic by mistake.

Your bi-stable circuit performs like a mono-stable circuit maybe because you didn't use a pcb (a lousy breadboard instead?) or because you didn't use shielded audio cable from the mic so your cable is picking up mains hum.
Maybe your power supply has too much hum.
 

hi
i made a pcb with the circuit , not a breadboard
and i used a 9 v battery not a transformer
so i do not think there is humming
thanks
 

i reversed the 2 pins it did not work it has its polarity
Click to expand...
This prooves, that the condenser microphone has a built-in amplifier.I assume that you have an electret transducer like this one: https://www.farnell.com/datasheets/95444.pdf

A classical condenser microphone must not necessarily be old. But's it's rather expensive professional equipment usually. Apart from the original DC polarized condenser microphone design, also RF capacitance transducers (e.g. from Sennheiser) and prepolarized (electret) microphones are used in the today's professionial microphone sector.
 

The metal case of an electret mic is its negative terminal that is usually connected to the shield of its cable. Electret mics are made as two-wire and as three-wire.
 

There are 11 Chinese mics. which one do you have??

Most or all of them are electret type, not condenser type.
Most or all of them are two-wire, not three-wire.
 

Now we finally clarified, that the circuit is matching the original schematic also regarding the microphone. Everyone convinced so far, that the microphone type isn't causing the problems?
 

hi
i have the one on that site
the one on the top left
hmmmmmm
it says it is a condenser mic even the salesman there said
it was a condenser mic hmmmm

but audioguru said most or all of them are electret mics
hmmmmmmmmmm
i am getting more confused now lol
regards

Added after 8 minutes:

hi
and one more thing
with the mic i have in the curcuit
i clap to turn it on , but i cannot turn it off ( it turns itself off after like 31 seconds)
when it is off , i can clap to turn it on again and then it turns itself off after like 31 seconds again the same things goes on and off
i do not think the mic part caused all these problems
according to the site it says we clap to turn it on and clap to turn it off
hmm
i guess like u guys said

the circuit is a bistable type
and it cannot be turned on and then off by clapping
( we can only turn it on )
regards
regards
 

It's all been said, to my opinion.

The microphone is O.K., it's not causing the problems. These microphones are all of the electret or "prepolarized" condenser microphone type, they are called just condenser by some catalog distributors, that's irrelevant.

For some reason, your circuit doesn't act correctly bistable, that means holding it's state infinitely. You can also disconnect the microphone and apply an electric pulse at the input, the behaviour is probably identical. If not, the microphone input may be too sensitive.
 

hi
thanks again
:)
but how can i apply electric pulse to the mic input after i take the mic out for testing?
regards
 

Why do you have two threads about the same circuit???
The bistable circuit has an error. I posted a correct schematic in your other thread about it:
 

Look sharp, the circuit can't work with 330 ohm (both transistors permanently off). Can't say, if the 330k is a good choice, but 330 ohm obviously isn't.

simonwai999 doesn't have the other thread, he only quoted it.

simon, shorting the microphone terminals and releasing the short should give a sufficient test pulse.
 

hi
ok folks
i will try to test it
and as audioguru said
there is one R should be changed to 3.3k or 330 ohms
i do not know if it would work
coz I do not have those resistors in hand
thanks anyway
regards
 

No, I was wrong. the original circuit should work fine if the transistors have their pins connected properly and the 10uF capacitors have the + terminal at the collectors of the transistors.

Of course, the diodes must be connected with the correct polarity.
 

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