[sdiy] Amplifying Pulse (Slightly OT)

[Kylee Kennedy]

Stethoscope around the chest listening to the heart...The subject will
have to hold their breath. Amp this and a rising trigger to a 555.
The problem with listening to the heart at the wrist will be as
described before and muscle movements.

Kylee


On Fri, Aug 10, 2018 at 4:02 AM,  <rburnett at richieburnett.co.uk> wrote:
> On 2018-08-10 10:23, Gordonjcp wrote:
>
>> Your pulse doesn't make any sound.  You can feel a slight flexing of the
>> radial artery when you take your pulse at your wrist, but it's way too
>> small and slow to make any noticeable sound.
>>
>> When you measure blood pressure with an old-fashioned sphygmomanometer
>> you're listening for blood scooshing through the brachial artery as the
>> air bladder in the cuff squeezes it shut.  You pump it up until the
>> noise stops (artery closed) then release the pressure until you just
>> start to hear it hiss through which gives you the systolic pressure, and
>> slowly release it some more until you just hear it as a faint tapping
>> for the diastolic pressure.
>
>
> A colleague across the office from me who's working on a project in this
> area said exactly the same as what Gordon said. Practically word for word.
>
>> Automatic sphygs use the change in pressure in the bladder to measure
>> it, apparently.  I've never had one apart.
>
>
> The "Oscillometric method" apparently, for anyone interested...
>
> https://en.wikipedia.org/wiki/Blood_pressure_measurement#Oscillometric
>
> -Richie,
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy