S
Simon Schneiter
Guest
ĄHello Everybody!
I'm working on a design using a piezo guitar-pickup that should be
conditioned for a A/D-converter (an then to a DSP and then ... but
thats another (long) story =
). The whole thing should be small and
not use too much power.
I've designed a circuit using single-rail supply, since the
A/D-converter requires the signal to be between 1V and 4V. I assumed
the peak output voltages of the piezo to be at +10V respectively -10V.
After looking around for quite a while I settled with a circuit I
found in "OpAmps For Everyone" which I found on the TI Website
(http://focus.ti.com/lit/an/slod006b/slod006b.pdf).
I read threads in this newsgroup and found some discussions about
designs for dual-supply opamps (e.g. "Piezo audio preamp works but I
would like advice" dating july'04).
I'm pretty lost about how to model the actual piezo-transducer and I'm
waiting to get the pickup delivered. So I couldn't do any mesurements
on them yet.(http://www.graphtech.com/product_display.asp?SearchType=brand&brand=Ghost)
I'm using a MAX4494 which I found after reading on the RANE-website
(http://www.rane.com/hilovolt.htm). The A/D-converter should be a
PCM1802 from Burr Brown (now with TI).
I'd be very happy if someone might have a look on the circuit I've
planned so far. I'm unsure if using single-supply altogether is a good
idea? Or should I look out for a opamp that has a FET-input stage to
achieve a even higher input impedance? Is it any worth to model the
piezo-pickup as a voltage source in series with a ~680pF capacitance,
or do I mislead myself using this in a spice-simulation? Is there
another circuit out there that fits my needs better?
I'm a graduate student in electrical engeneering, but not experienced
with anlog stuff. And I'd happy to get the signal in an decent quality
into the digital domain, where I'm more comfortable
I put some screenshots of my current circuit and the simulations I did
on my website:
(http://www.dirtybit.ch/temp/piezo/)
One shows the circuit, including operation-point voltages and current
markers.
Thanks for anyone giving me hints/comments/help on this!
Simon
===============
Simon Schneiter
www.dirtybit.ch
===============
Switzerland, CH
===============
I'm working on a design using a piezo guitar-pickup that should be
conditioned for a A/D-converter (an then to a DSP and then ... but
thats another (long) story =
). The whole thing should be small andnot use too much power.
I've designed a circuit using single-rail supply, since the
A/D-converter requires the signal to be between 1V and 4V. I assumed
the peak output voltages of the piezo to be at +10V respectively -10V.
After looking around for quite a while I settled with a circuit I
found in "OpAmps For Everyone" which I found on the TI Website
(http://focus.ti.com/lit/an/slod006b/slod006b.pdf).
I read threads in this newsgroup and found some discussions about
designs for dual-supply opamps (e.g. "Piezo audio preamp works but I
would like advice" dating july'04).
I'm pretty lost about how to model the actual piezo-transducer and I'm
waiting to get the pickup delivered. So I couldn't do any mesurements
on them yet.(http://www.graphtech.com/product_display.asp?SearchType=brand&brand=Ghost)
I'm using a MAX4494 which I found after reading on the RANE-website
(http://www.rane.com/hilovolt.htm). The A/D-converter should be a
PCM1802 from Burr Brown (now with TI).
I'd be very happy if someone might have a look on the circuit I've
planned so far. I'm unsure if using single-supply altogether is a good
idea? Or should I look out for a opamp that has a FET-input stage to
achieve a even higher input impedance? Is it any worth to model the
piezo-pickup as a voltage source in series with a ~680pF capacitance,
or do I mislead myself using this in a spice-simulation? Is there
another circuit out there that fits my needs better?
I'm a graduate student in electrical engeneering, but not experienced
with anlog stuff. And I'd happy to get the signal in an decent quality
into the digital domain, where I'm more comfortable
I put some screenshots of my current circuit and the simulations I did
on my website:
(http://www.dirtybit.ch/temp/piezo/)
One shows the circuit, including operation-point voltages and current
markers.
Thanks for anyone giving me hints/comments/help on this!
Simon
===============
Simon Schneiter
www.dirtybit.ch
===============
Switzerland, CH
===============