Need a sample & hold, low frequency to voltage circuit, no output drift.
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Posted by on August 27, 2008, 3:51 pm
Please log in for more thread options I am working on a hobby project and would like to find a "single chip" solution or "circuit" for a sample & hold frequency to voltage converter with a no drift output. I have a generated audio range of 50 Hz to 300 Hz I would like to correlate the Output voltage range as: 5v @ 50 Hz - to - 8v @ 300 Hz A new update or sample pulse would be once every 10 minutes. The output voltage must hold solid, in other words absolutely drift/decay free between 10 minute intervals. I tried a 1 Meg resistor and a 1 uf film capacitor on a TL082 OP Amp input with the unacceptable output voltage decay shown below. Decay Time 5.58v 12:33 5.57v 12:36 5.56v 12:41 5.55v 12:46 5.54v 12:53 The ideal chip would be 8 pin and drift free on the Output. It needs to operate from a single 9 volt battery, so minimum current drain is important. Any chip or circuit recommendation is appreciated. Thank you for your insight and sharing your knowledge * * * * Christopher Temecula CA.USA http://www.oldtemecula.com | |||||||||||||
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Posted by on August 27, 2008, 4:17 pm
Please log in for more thread options On Wed, 27 Aug 2008 19:51:52 GMT, christopher@NOSPAMoldtemecula.com wrote: I can do the frequency to voltage conversion fine. What I need is an 8 pin chip that can work at 9 volts with low current drain. It must take a 4 to 8 volt sample voltage at the input and hold that same value on the Output indefinitely or until it receives an update pulse. Thanks again, * * * * Christopher Temecula CA.USA http://www.oldtemecula.com | |||||||||||||
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Posted by John Fields on August 27, 2008, 5:15 pm
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On Wed, 27 Aug 2008 20:17:43 GMT, christopher@NOSPAMoldtemecula.com wrote: >On Wed, 27 Aug 2008 19:51:52 GMT, christopher@NOSPAMoldtemecula.com
>wrote: > >>I am working on a hobby project and would like to find a "single chip"
>>solution or "circuit" for a sample & hold frequency to voltage >>converter with a no drift output. >> >>I have a generated audio range of 50 Hz to 300 Hz >> >> I would like to correlate the Output voltage range as: >> 5v @ 50 Hz - to - 8v @ 300 Hz >> >>A new update or sample pulse would be once every 10 minutes. The >>output voltage must hold solid, in other words absolutely drift/decay >>free between 10 minute intervals. >> >>I tried a 1 Meg resistor and a 1 uf film capacitor on a TL082 OP Amp >>input with the unacceptable output voltage decay shown below. >> >>Decay Time >>5.58v 12:33 >>5.57v 12:36 >>5.56v 12:41 >>5.55v 12:46 >>5.54v 12:53 >> >>The ideal chip would be 8 pin and drift free on the Output. It needs >>to operate from a single 9 volt battery, so minimum current drain is >>important. >> >>Any chip or circuit recommendation is appreciated. >
> >I can do the frequency to voltage conversion fine. What I need is an 8 >pin chip that can work at 9 volts with low current drain. It must take >a 4 to 8 volt sample voltage at the input and hold that same value on >the Output indefinitely or until it receives an update pulse. --- Vin>---[ADC]---[LATCH]---[DAC]-->Vout
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SAMPLE>--+--------+
JF | |||||||||||||
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Posted by on August 28, 2008, 10:23 am
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On Wed, 27 Aug 2008 16:15:33 -0500, John Fields >>I can do the frequency to voltage conversion fine. What I need is an 8
>>pin chip that can work at 9 volts with low current drain. It must take >>a 4 to 8 volt sample voltage at the input and hold that same value on >>the Output indefinitely or until it receives an update pulse. >
>--- > >Vin>---[ADC]---[LATCH]---[DAC]-->Vout
> | |
>SAMPLE>--+--------+ Thank you John, that gave me the proper logic for the information I began searching for. Google is not my friend on this one. ;-( * * * * Christopher Temecula CA.USA http://www.oldtemecula.com | |||||||||||||
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Posted by John Fields on August 28, 2008, 12:51 pm
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On Thu, 28 Aug 2008 14:23:52 GMT, christopher@REMOVEoldtemecula.com wrote: >On Wed, 27 Aug 2008 16:15:33 -0500, John Fields
> >>>I can do the frequency to voltage conversion fine. What I need is an 8
>>>pin chip that can work at 9 volts with low current drain. It must take >>>a 4 to 8 volt sample voltage at the input and hold that same value on >>>the Output indefinitely or until it receives an update pulse. >>
>>--- >> >>Vin>---[ADC]---[LATCH]---[DAC]-->Vout
>> | |
>>SAMPLE>--+--------+ >
> >Thank you John, that gave me the proper logic for the information I >began searching for. Google is not my friend on this one. ;-( --- It might be... Search for CODEC. :-) BTW, why are you limited to an 8 pin chip? JF | |||||||||||||
>solution or "circuit" for a sample & hold frequency to voltage
>converter with a no drift output.
>
>I have a generated audio range of 50 Hz to 300 Hz
>
> I would like to correlate the Output voltage range as:
> 5v @ 50 Hz - to - 8v @ 300 Hz
>
>A new update or sample pulse would be once every 10 minutes. The
>output voltage must hold solid, in other words absolutely drift/decay
>free between 10 minute intervals.
>
>I tried a 1 Meg resistor and a 1 uf film capacitor on a TL082 OP Amp
>input with the unacceptable output voltage decay shown below.
>
>Decay Time
>5.58v 12:33
>5.57v 12:36
>5.56v 12:41
>5.55v 12:46
>5.54v 12:53
>
>The ideal chip would be 8 pin and drift free on the Output. It needs
>to operate from a single 9 volt battery, so minimum current drain is
>important.
>
>Any chip or circuit recommendation is appreciated.