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simonwai999
Joined: 30 Jun 2008
Posts: 113
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 07 Aug 2008 19:58 Re: condenser and electret mics |
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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?
http://www.edaboard.com/viewtopic.php?p=705784#705784
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
http://saint.419.removed.us/clapsw.html
can any smart fellows in this forum clear my doubts?
Thanks a lot
Ps: I connected exactly like the circuit
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 07 Aug 2008 21:36 condenser and electret mics |
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| 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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 08 Aug 2008 14:25 Re: condenser and electret mics |
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hi pal
i do not quite understand
what do you mean by my last wrong sentence?
i really followed this circuit
http://www.edaboard.com/viewtopic.php?p=705784#705784
in every details
except i used a condenser mic
one more thing is the circuit using bistable ?
Thanks
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GrandAlf
Joined: 09 Mar 2002
Posts: 291
Helped: 14
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| 08 Aug 2008 16:24 condenser and electret mics |
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| 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
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 08 Aug 2008 16:35 Re: condenser and electret mics |
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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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 08 Aug 2008 17:23 Re: condenser and electret mics |
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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
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 10 Aug 2008 4:58 condenser and electret mics |
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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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 10 Aug 2008 5:51 Re: condenser and electret mics |
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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
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 10 Aug 2008 9:19 Re: condenser and electret mics |
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| Quote: |
| i reversed the 2 pins it did not work it has its polarity |
This prooves, that the condenser microphone has a built-in amplifier.I assume that you have an electret transducer like this one: http://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.
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 10 Aug 2008 15:47 condenser and electret mics |
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| 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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 10 Aug 2008 17:22 Re: condenser and electret mics |
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HI
ok guys
here is the mic i got
i got it from this shop
here it is the link
http://www.weclonline.com/tchi/search.asp?display=photo&page=1&txtitle=CONDENSER+MIC&search=0
regards
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 10 Aug 2008 17:30 condenser and electret mics |
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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.
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 10 Aug 2008 18:05 condenser and electret mics |
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| 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?
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 11 Aug 2008 6:10 Re: condenser and electret mics |
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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
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 11 Aug 2008 7:10 Re: condenser and electret mics |
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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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 11 Aug 2008 18:02 Re: condenser and electret mics |
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hi
thanks again
but how can i apply electric pulse to the mic input after i take the mic out for testing?
regards
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 11 Aug 2008 19:13 condenser and electret mics |
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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:
http://www.edaboard.com/viewtopic.php?p=1067318#1067318
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 11 Aug 2008 21:15 condenser and electret mics |
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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.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 12 Aug 2008 6:04 Re: condenser and electret mics |
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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
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 13 Aug 2008 16:02 condenser and electret mics |
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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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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 13 Aug 2008 16:37 Re: condenser and electret mics |
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hi
i got your reply audioguru
the diode polarities are all correct
and the + of the two 10 uf caps are connected to the collectors of both transistors too
but like i said from the beginning
after i connected the things exactly like the curcuit
i can clap to turn it on and then it turns itself off in about 31 seconds( i cannot turn it off by clapping)
and when it is off i can clap to turn it on again but then it turns itself off in about 31 seconds
the same goes on in this fashion
according to what it says on the site
the advice is like we clap to turn on the lamp and clap to turn it off
the result shows something totally diff
obviously something wrong with the curcuit
the bistable circuit cannot change states
regards
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 14 Aug 2008 19:10 Re: condenser and electret mics |
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hi
audioguru
yes i even checked the transistors bc547 and bc337 pinouts
both t92 type
flat side facing us
from left to right
collector base and emitter
i also measured the 9v battery voltage it is above 8 v dc
regards
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 15 Aug 2008 1:22 condenser and electret mics |
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Maybe the circuit has a leaky capacitor that conducts.
Maybe a resistor is the wrong value or is open.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 15 Aug 2008 5:45 Re: condenser and electret mics |
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hi
thx for your reply audiguru
i do not have extra caps here
i will get some and check all connections once again and report to you later
thanks again
regards
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neelandan
Joined: 26 Mar 2004
Posts: 28
Helped: 1
Location: Terra Firma
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| 19 Aug 2008 7:23 Re: condenser and electret mics |
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You might have bought schottky diodes in place of the 1N4148 specified. Or the place you bought them from might have supplied them instead. For most applications, this does not matter much.
However, this bistable circuit uses the 1N4148 in the emitter of one of the transistors in order to compensate for the additional voltage drop due to the Vbe of the BC337 at the other.
Try changing that diode. Buy a 1N4001 and stick it in place of that diode and see how it works out.
The original circuit works as a monostable if that diode in the emitter is omitted.
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 19 Aug 2008 16:13 Re: condenser and electret mics |
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The "amplifier" transistor in the photo does not have a base bias resistor.
But then the original circuit doesn't either because the value of 4.7M is much too high.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 19 Aug 2008 17:43 Re: condenser and electret mics |
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hi guys
so the base resistor of the amp is too high
hmmmmmmm
and i need to change the in4148
hmmmmmmmmm
i feel like i will have to change many things now
hold on anything
i am gonna try all these now
since i got the in4001 and some new caps
regards
Added after 32 minutes:
hi guys
i finally made it work
reporting:)
i changed some parts
the amp input 10uf i changed it to a new 10uf cap i bought today
i changed the amp 4.7M to 47k(aduioguru said this value is too high so i changed it to 47 k and tried and it worked)
i also changed the bc547 emitter diode in4148 to in 4001
and i also changed that 100nf to 10 nf( the clap switch is now not as sensitive as it was the first time it was too sensitive but now it is better)
all working fine now
thanks for all replies and teaching
regards
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FvM
Joined: 22 Jan 2008
Posts: 2679
Helped: 438
Location: Bochum, Germany
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| 19 Aug 2008 19:48 Re: condenser and electret mics |
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| the value of 4.7M is much too high |
Not necessarily. You can imagine the transistor stage also as prebiased switch. It don't need to amplify the input signal undistorted. So I think, the circuit is O.K, if the sensitivity is sufficiant. Your right of course regarding the wallpaper circuit.
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Audioguru
Joined: 19 Jan 2008
Posts: 519
Helped: 39
Location: Canada
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| 20 Aug 2008 0:31 condenser and electret mics |
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With a 4.7M base resistor, the transistor is cutoff.
If a clap makes a negative-going signal then the transistor "amplifier" won't do anything.
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simonwai999
Joined: 30 Jun 2008
Posts: 113
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| 20 Aug 2008 6:54 Re: condenser and electret mics |
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hi guys
thanks again
it is working finally
simon
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