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microphones with very low current consumption
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elil
Feb 7, 2012, 8:29:44 AM2/7/12
to
Dear,
I'm looking for ideas about microphones with very low current
consumption (say, less than few uA) and low cost(say less than $1).
Electret microphone elements typically include a JFET as an impedance
converter and the operating current of this JFET is typically 0.1 to
0.5 mA. As far as I know, there are microphones without JFET, so it
might be one of my alternatives.
Recently I checked yet another 2 options: Magnetic microphone and
Dynamic receiver. But once I had heard the prices for these parts, I
have stopped thinking about them.
Any suggestions and comments will be highly appreciated.
Best regards,
Eli
I'm looking for ideas about microphones with very low current
consumption (say, less than few uA) and low cost(say less than $1).
Electret microphone elements typically include a JFET as an impedance
converter and the operating current of this JFET is typically 0.1 to
0.5 mA. As far as I know, there are microphones without JFET, so it
might be one of my alternatives.
Recently I checked yet another 2 options: Magnetic microphone and
Dynamic receiver. But once I had heard the prices for these parts, I
have stopped thinking about them.
Any suggestions and comments will be highly appreciated.
Best regards,
Eli
Syd Rumpo
Feb 7, 2012, 9:46:44 AM2/7/12
to
Cheers
--
Syd
elil
Feb 7, 2012, 12:42:50 PM2/7/12
to
found anything. Don't forget another requirement-low cost
Tim Wescott
Feb 7, 2012, 12:51:31 PM2/7/12
to
Or a bare electret element, to which you attach your own JFET, carefully
controlled for current (although I must admit to having absolutely no
clue of how easy it is to get bare electrets)
In any microphone circuit you should consider the amount of current
you'll need in the following amplifier -- you certainly aren't going to
get a transducer that can directly power the following equipment.
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Syd Rumpo
Feb 7, 2012, 12:59:32 PM2/7/12
to
is low cost. What sort of sensitivity and signal type? Just a whistle
or a hand-clap or a Hi-Fi recording?
Cheers
--
Syd
Vladimir Vassilevsky
Feb 7, 2012, 1:31:08 PM2/7/12
to
elil wrote:
> Dear,
>
> I'm looking for ideas about microphones with very low current
> consumption (say, less than few uA) and low cost(say less than $1).
>
> Any suggestions and comments will be highly appreciated.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
Les Cargill
Feb 7, 2012, 1:54:27 PM2/7/12
to
peizo mics generally have extremely poor frequency
response. I'm hedging because that could just have
been implementation, but I somehow doubt it.
--
Les Cargill
Syd Rumpo
Feb 7, 2012, 2:32:29 PM2/7/12
to
On 07/02/2012 18:54, Les Cargill wrote:
<snip>
For some reason, crystal microphones retain a niche for use with mouth
organs, which maybe implies a fairly restricted frequency response, but
'extremely poor' seems a bit extreme.
Cheers
--
Syd
<snip>
>
> Correct me if I am wrong, but my understanding is that
> peizo mics generally have extremely poor frequency
> response. I'm hedging because that could just have
> been implementation, but I somehow doubt it.
>
> --
> Les Cargill
Yes they're not Hi-Fi, but the OP didn't specify, and they're sensitive.
> Correct me if I am wrong, but my understanding is that
> peizo mics generally have extremely poor frequency
> response. I'm hedging because that could just have
> been implementation, but I somehow doubt it.
>
> --
> Les Cargill
For some reason, crystal microphones retain a niche for use with mouth
organs, which maybe implies a fairly restricted frequency response, but
'extremely poor' seems a bit extreme.
Cheers
--
Syd
Hans-Bernhard Bröker
Feb 7, 2012, 4:23:13 PM2/7/12
to
On 07.02.2012 14:29, elil wrote:
> I'm looking for ideas about microphones with very low current
> consumption (say, less than few uA) and low cost(say less than $1).
> Electret microphone elements typically include a JFET as an impedance
> converter and the operating current of this JFET is typically 0.1 to
> 0.5 mA.
And you're really sure the reason microphone manufacturers put those
> I'm looking for ideas about microphones with very low current
> consumption (say, less than few uA) and low cost(say less than $1).
> Electret microphone elements typically include a JFET as an impedance
> converter and the operating current of this JFET is typically 0.1 to
> 0.5 mA.
JFETs in there doesn't apply to you? Are you 100% fire-proof certain
that you can live with the impedance you would have without that conversion?
Anyway, specifying a current consumption all by itself is somewhat
devoid of meaning. Say there was a microphone with 1 渙 current from a
100 kV supply. Would that satisfy your request? Or was it actually a
_power_ restriction you were after?
Tim Wescott
Feb 7, 2012, 6:01:15 PM2/7/12
to
On Tue, 07 Feb 2012 22:23:13 +0100, Hans-Bernhard Bröker wrote:
> On 07.02.2012 14:29, elil wrote:
>
>> I'm looking for ideas about microphones with very low current
>> consumption (say, less than few uA) and low cost(say less than $1).
>> Electret microphone elements typically include a JFET as an impedance
>> converter and the operating current of this JFET is typically 0.1 to
>> 0.5 mA.
>
> And you're really sure the reason microphone manufacturers put those
> JFETs in there doesn't apply to you? Are you 100% fire-proof certain
> that you can live with the impedance you would have without that
> conversion?
>
> Anyway, specifying a current consumption all by itself is somewhat
> devoid of meaning. Say there was a microphone with 1 µA current from a
> On 07.02.2012 14:29, elil wrote:
>
>> I'm looking for ideas about microphones with very low current
>> consumption (say, less than few uA) and low cost(say less than $1).
>> Electret microphone elements typically include a JFET as an impedance
>> converter and the operating current of this JFET is typically 0.1 to
>> 0.5 mA.
>
> And you're really sure the reason microphone manufacturers put those
> JFETs in there doesn't apply to you? Are you 100% fire-proof certain
> that you can live with the impedance you would have without that
> conversion?
>
> Anyway, specifying a current consumption all by itself is somewhat
> 100 kV supply. Would that satisfy your request? Or was it actually a
> _power_ restriction you were after?
Picky picky.
> _power_ restriction you were after?
And, to reiterate, would an $0.10 microphone that needs no current and
puts out a microvolt when you shout at it be sufficient, or do you have
some sensitivity requirements?
(Because ceramic capacitors do tend to be microphonic. And cheap).
Mark Borgerson
Feb 7, 2012, 7:48:30 PM2/7/12
to
In article <jcSdneKhqc0--azS...@web-ster.com>,
t...@seemywebsite.com says...
able to convert speech to electricity and back to sound with no
amplification. Earmuff-type headphones and a loud voice made up for the
losses in the signal path..(I suppose the dynamic range of the human ear
certainly helps ! ;-)
A good voice-coil microphone would work with a lot of A/D converters.
A peizo microphone might work with a transformer to match to a
relatively high-impedance ADC input.
Mark Borgerson
t...@seemywebsite.com says...
>
> On Tue, 07 Feb 2012 14:46:44 +0000, Syd Rumpo wrote:
>
> > On 07/02/2012 13:29, elil wrote:
> >> Dear,
> >>
> >> I'm looking for ideas about microphones with very low current
> >> consumption (say, less than few uA) and low cost(say less than $1).
> >> Electret microphone elements typically include a JFET as an impedance
> >> converter and the operating current of this JFET is typically 0.1 to
> >> 0.5 mA. As far as I know, there are microphones without JFET, so it
> >> might be one of my alternatives.
> >> Recently I checked yet another 2 options: Magnetic microphone and
> >> Dynamic receiver. But once I had heard the prices for these parts, I
> >> have stopped thinking about them.
> >>
> >> Any suggestions and comments will be highly appreciated.
> >>
> >> Best regards,
> >> Eli
> >
> > Piezoelectric (crystal) microphone.
> >
> > Cheers
>
> That may actually work.
>
> Or a bare electret element, to which you attach your own JFET, carefully
> controlled for current (although I must admit to having absolutely no
> clue of how easy it is to get bare electrets)
>
> In any microphone circuit you should consider the amount of current
> you'll need in the following amplifier -- you certainly aren't going to
> get a transducer that can directly power the following equipment.
That depends on the following equipment. Sound-powered telephones are
> On Tue, 07 Feb 2012 14:46:44 +0000, Syd Rumpo wrote:
>
> > On 07/02/2012 13:29, elil wrote:
> >> Dear,
> >>
> >> I'm looking for ideas about microphones with very low current
> >> consumption (say, less than few uA) and low cost(say less than $1).
> >> Electret microphone elements typically include a JFET as an impedance
> >> converter and the operating current of this JFET is typically 0.1 to
> >> 0.5 mA. As far as I know, there are microphones without JFET, so it
> >> might be one of my alternatives.
> >> Recently I checked yet another 2 options: Magnetic microphone and
> >> Dynamic receiver. But once I had heard the prices for these parts, I
> >> have stopped thinking about them.
> >>
> >> Any suggestions and comments will be highly appreciated.
> >>
> >> Best regards,
> >> Eli
> >
> > Piezoelectric (crystal) microphone.
> >
> > Cheers
>
> That may actually work.
>
> Or a bare electret element, to which you attach your own JFET, carefully
> controlled for current (although I must admit to having absolutely no
> clue of how easy it is to get bare electrets)
>
> In any microphone circuit you should consider the amount of current
> you'll need in the following amplifier -- you certainly aren't going to
> get a transducer that can directly power the following equipment.
able to convert speech to electricity and back to sound with no
amplification. Earmuff-type headphones and a loud voice made up for the
losses in the signal path..(I suppose the dynamic range of the human ear
certainly helps ! ;-)
A good voice-coil microphone would work with a lot of A/D converters.
A peizo microphone might work with a transformer to match to a
relatively high-impedance ADC input.
Mark Borgerson
Tim Wescott
Feb 7, 2012, 8:13:00 PM2/7/12
to
electrical energy than the mechanical energy needed to drive them, at the
cost of needing way more bias current, at way more voltage, than an
electret.
Early telephone amplifiers actually used a sounder connected to a carbon
mic, and exhibited electrical gain.
> A good voice-coil microphone would work with a lot of A/D converters. A
> peizo microphone might work with a transformer to match to a relatively
> high-impedance ADC input.
he's already checked for pricing straight from China, though.
elil
Feb 9, 2012, 5:40:43 AM2/9/12
to
I can't tell you yet the desired sensitivity requirements, but I would
say I need quite sensitive microphone. After microphone I have MCU
with 12-bit ADC and/or comparator,
so it is better to get oversensitivity than undersensitivity. The
device is to be operated by 3V Lithium battery, i.e. VCC range within
2.5-3.3V or, if I use volatge regulator, 2.5V.
Regarding the idea to use capacitor as a microphone, actually electret
microphone is a capacitor with JFET. There is an option to ask
supplier for a part without JFET,
and then, seemingly, I get a possible silution, however I get here a
hard task here to amplify high frequency signals of microhone output
with high impedance.
All that with cheap and low current means.
Regards,
Eli
Hans-Bernhard Bröker
Feb 9, 2012, 5:12:16 PM2/9/12
to
On 09.02.2012 11:40, elil wrote:
> Thank you all for your comments.
> I can't tell you yet the desired sensitivity requirements, but I would
> say I need quite sensitive microphone. After microphone I have MCU
> with 12-bit ADC and/or comparator,
> so it is better to get oversensitivity than undersensitivity. The
> device is to be operated by 3V Lithium battery, i.e. VCC range within
> 2.5-3.3V or, if I use volatge regulator, 2.5V.
That's doesn't feel right. Why try so hard to get the microphone's
> Thank you all for your comments.
> I can't tell you yet the desired sensitivity requirements, but I would
> say I need quite sensitive microphone. After microphone I have MCU
> with 12-bit ADC and/or comparator,
> so it is better to get oversensitivity than undersensitivity. The
> device is to be operated by 3V Lithium battery, i.e. VCC range within
> 2.5-3.3V or, if I use volatge regulator, 2.5V.
consumption all that far down, when your MCU is going to consume orders
of magnitude more than that, anyway?
Mark Borgerson
Feb 10, 2012, 8:50:31 PM2/10/12
to
In article <9piulr...@mid.dfncis.de>, HBBr...@t-online.de says...
Good point. In order for the onboard ADC to digitize at audio rates,
the MPU clock can't be slowed down too far, so the MPU power should
be much larger than the drain through a FET on a microphone.
A good processing algorithm that minimizes the required CPU cycles
might save a lot more power than you could ever save at the microphone.
Mark Borgerson
the MPU clock can't be slowed down too far, so the MPU power should
be much larger than the drain through a FET on a microphone.
A good processing algorithm that minimizes the required CPU cycles
might save a lot more power than you could ever save at the microphone.
Mark Borgerson
I
Feb 13, 2012, 2:25:18 AM2/13/12
to
On 11 פברואר, 03:50, Mark Borgerson <mborger...@comcast.net> wrote:
> In article <9piulrFt3...@mid.dfncis.de>, HBBroe...@t-online.de says...
Dear Mark and Hans,
In my application, signal processing is an asynchronic and a very rare
task, so MCU will not wast its power for constant digitalization and
signal processing, as you have assumed. Generally, MCU will be
sleeping with slow wakeup period of 1 sec and will be woken up when
some asynchronic event(for example one of microphone) happens. I
would like to connect the microphone output to a comparator that will
trigger MCU when microphone output goes over some threshold. All my
application, without radio module, should consume
7-12 uA @ 3V in average.
Eli.
> In article <9piulrFt3...@mid.dfncis.de>, HBBroe...@t-online.de says...
In my application, signal processing is an asynchronic and a very rare
task, so MCU will not wast its power for constant digitalization and
signal processing, as you have assumed. Generally, MCU will be
sleeping with slow wakeup period of 1 sec and will be woken up when
some asynchronic event(for example one of microphone) happens. I
would like to connect the microphone output to a comparator that will
trigger MCU when microphone output goes over some threshold. All my
application, without radio module, should consume
7-12 uA @ 3V in average.
Eli.
aldito
Mar 13, 2012, 9:42:21 PM3/13/12
to
>On 11 =D7=A4=D7=91=D7=A8=D7=95=D7=90=D7=A8, 03:50, Mark Borgerson
<mborger.=
microphone'=
rates=
I hope you already found the microphone, but I know is not easy. I'm also
looking for a very low power electret mic, without success. Why you don't
turn on the mic only for few miliseconds to check if there is the "event"?
I suggest you take a look to the TI application SLAA389 for a glassbreak
detector: A Robust Glass-Breakage Detector Using the MSP430. They turn on
the mic for 20uS every 2.5mS. When the mic is on and the MCU is working
(20uS) the current is 4.8mA, then for 2.5mS the MCU goes to low power and
the current is 0.6uA.
Regards,
Aldo.
---------------------------------------
Posted through http://www.EmbeddedRelated.com
<mborger.=
>..@comcast.net> wrote:
>> In article <9piulrFt3...@mid.dfncis.de>, HBBroe...@t-online.de says...
>>
>>
>>
>> > On 09.02.2012 11:40, elil wrote:
>>
>> > > Thank you all for your comments.
>> > > I can't tell you yet the desired sensitivity requirements, but I
woul=
>> In article <9piulrFt3...@mid.dfncis.de>, HBBroe...@t-online.de says...
>>
>>
>>
>> > On 09.02.2012 11:40, elil wrote:
>>
>> > > Thank you all for your comments.
>> > > I can't tell you yet the desired sensitivity requirements, but I
>d
>> > > say I need quite sensitive microphone. After microphone I have MCU
>> > > with 12-bit ADC and/or comparator,
>> > > so it is better to get oversensitivity than undersensitivity. The
>> > > device is to be operated by 3V Lithium battery, i.e. VCC range
within
>> > > 2.5-3.3V or, if I use volatge regulator, 2.5V.
>>
>> > That's doesn't feel right. =C2=A0Why try so hard to get the
>> > > say I need quite sensitive microphone. After microphone I have MCU
>> > > with 12-bit ADC and/or comparator,
>> > > so it is better to get oversensitivity than undersensitivity. The
>> > > device is to be operated by 3V Lithium battery, i.e. VCC range
within
>> > > 2.5-3.3V or, if I use volatge regulator, 2.5V.
>>
microphone'=
>s
>> > consumption all that far down, when your MCU is going to consume
orders
>> > of magnitude more than that, anyway?
>>
>> Good point. =C2=A0In order for the onboard ADC to digitize at audio
>> > consumption all that far down, when your MCU is going to consume
orders
>> > of magnitude more than that, anyway?
>>
rates=
>,
>> the MPU clock can't be slowed down too far, so the MPU power should
>> be much larger than the drain through a FET on a microphone.
>>
>> A good processing algorithm that minimizes the required CPU cycles
>> might save a lot more power than you could ever save at the microphone.
>>
>> Mark Borgerson
>
>Dear Mark and Hans,
>
>In my application, signal processing is an asynchronic and a very rare
>task, so MCU will not wast its power for constant digitalization and
>signal processing, as you have assumed. Generally, MCU will be
>sleeping with slow wakeup period of 1 sec and will be woken up when
>some asynchronic event(for example one of microphone) happens. I
>would like to connect the microphone output to a comparator that will
>trigger MCU when microphone output goes over some threshold. All my
>application, without radio module, should consume
>7-12 uA @ 3V in average.
>Eli.
>
Dear Eli,
>> the MPU clock can't be slowed down too far, so the MPU power should
>> be much larger than the drain through a FET on a microphone.
>>
>> A good processing algorithm that minimizes the required CPU cycles
>> might save a lot more power than you could ever save at the microphone.
>>
>> Mark Borgerson
>
>Dear Mark and Hans,
>
>In my application, signal processing is an asynchronic and a very rare
>task, so MCU will not wast its power for constant digitalization and
>signal processing, as you have assumed. Generally, MCU will be
>sleeping with slow wakeup period of 1 sec and will be woken up when
>some asynchronic event(for example one of microphone) happens. I
>would like to connect the microphone output to a comparator that will
>trigger MCU when microphone output goes over some threshold. All my
>application, without radio module, should consume
>7-12 uA @ 3V in average.
>Eli.
>
I hope you already found the microphone, but I know is not easy. I'm also
looking for a very low power electret mic, without success. Why you don't
turn on the mic only for few miliseconds to check if there is the "event"?
I suggest you take a look to the TI application SLAA389 for a glassbreak
detector: A Robust Glass-Breakage Detector Using the MSP430. They turn on
the mic for 20uS every 2.5mS. When the mic is on and the MCU is working
(20uS) the current is 4.8mA, then for 2.5mS the MCU goes to low power and
the current is 0.6uA.
Regards,
Aldo.
---------------------------------------
Posted through http://www.EmbeddedRelated.com
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