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.
> 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.
> > 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
> --
> Syd
...I already have been looking for such components but still haven't
found anything. Don't forget another requirement-low cost
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.
-- 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?
> On 7 פברואר, 16:46, Syd Rumpo<use...@neonica.co.uk> 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
>> --
>> Syd
> ...I already have been looking for such components but still haven't
> found anything. Don't forget another requirement-low cost
Depends what you need. A simple piezo sounder element may suffice and is low cost. What sort of sensitivity and signal type? Just a whistle or a hand-clap or a Hi-Fi recording?
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
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.
> 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. 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.
> 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 100 kV supply. Would that satisfy your request? Or was it actually a _power_ restriction you were after?
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
> 100 kV supply. Would that satisfy your request? Or was it actually a
> _power_ restriction you were after?
Picky picky.
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).
-- 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?
> 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
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.
On Tue, 07 Feb 2012 16:48:30 -0800, Mark Borgerson wrote:
> In article <jcSdneKhqc0--azSnZ2dnUVZ_t6dn...@web-ster.com>,
> 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
> 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 ! ;-)
Carbon microphones are electro-mechanical amplifiers; they put out more 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.
True, but the OP has already ruled that out as he wants cheap. Dunno if he's already checked for pricing straight from China, though.
-- 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?
> 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
> > 100 kV supply. Would that satisfy your request? Or was it actually a
> > _power_ restriction you were after?
> Picky picky.
> 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).
> --
> 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?
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.
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.
> 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 consumption all that far down, when your MCU is going to consume orders of magnitude more than that, anyway?
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 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 > consumption all that far down, when your MCU is going to consume orders > of magnitude more than that, anyway?
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.
> 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 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
> > consumption all that far down, when your MCU is going to consume orders
> > of magnitude more than that, anyway?
> 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
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.
>On 11 =D7=A4=D7=91=D7=A8=D7=95=D7=90=D7=A8, 03:50, Mark Borgerson
<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=
>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
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
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,
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.
