Hey guys,
Just a brief intro...
At the moment I'm (trying) to do my final year project for my mechanical engineering masters. As such my knowledge of electronics is somewhat "fuzzy" to say the least and I need a little help and guidance. I've been assigned a project designing a magnetic bearing system which while interesting is a little beyond the scope of my basic electronics knowledge.
At the moment I'm trying to get my head around the oscillator circuit and amplifier. I've done the circuit for the oscillator which "should" oscillate at 50kHz, Image below if all has worked well. I'm connecting the +ve and -ve terminals of the op-amp to +5v and ground respectively and the non inverting input of the first op-amp will be +2.5V. So this should be oscillating between 0 and 5V at close to 50kHz.
The Op-amp is an TLV2474 from RS
http://uk.rs-online.com/web/p/operational-amplifiers/6612230/
Resistor values I've chosen are
R=4,700Ohms
Rf=27,000 Ohms + Variable resistor in series to allow for some adjustment
Rg=6,800 Ohms
Rf/Rg=1 to get gain to unity
Capacitor
C=680 picoFarads
I'm fairly comfortable with this part, I'll be hooking it up to an oscilloscope tomorrow to check it works.
What I'm not sure is how to convert the very small signal coming out of the oscillator to a true bi-directional signal strong enough to drive my sensor.
My plan at the moment is to use a Darlington pair to amplify my signal and allow me to draw more current without distorting the sinewave, then put a capacitor on the output (1 micro Farad) to block the DC offset. By my understanding this will give me the AC signal shifted down to +12V to -12V as long as I do the Darlington pair part right is this correct?
My second question, how do I actually use the Darlington pair to amplify but not distort my signal? Should I be looking at something different for amplifying the signal?
Sorry if this seems very simple but I'm looking for someone with know how to point out if I've made any blindingly obvious mistakes this far.
Thanks for any help!
Just a brief intro...
At the moment I'm (trying) to do my final year project for my mechanical engineering masters. As such my knowledge of electronics is somewhat "fuzzy" to say the least and I need a little help and guidance. I've been assigned a project designing a magnetic bearing system which while interesting is a little beyond the scope of my basic electronics knowledge.
At the moment I'm trying to get my head around the oscillator circuit and amplifier. I've done the circuit for the oscillator which "should" oscillate at 50kHz, Image below if all has worked well. I'm connecting the +ve and -ve terminals of the op-amp to +5v and ground respectively and the non inverting input of the first op-amp will be +2.5V. So this should be oscillating between 0 and 5V at close to 50kHz.
The Op-amp is an TLV2474 from RS
http://uk.rs-online.com/web/p/operational-amplifiers/6612230/
Resistor values I've chosen are
R=4,700Ohms
Rf=27,000 Ohms + Variable resistor in series to allow for some adjustment
Rg=6,800 Ohms
Rf/Rg=1 to get gain to unity
Capacitor
C=680 picoFarads
I'm fairly comfortable with this part, I'll be hooking it up to an oscilloscope tomorrow to check it works.
What I'm not sure is how to convert the very small signal coming out of the oscillator to a true bi-directional signal strong enough to drive my sensor.
My plan at the moment is to use a Darlington pair to amplify my signal and allow me to draw more current without distorting the sinewave, then put a capacitor on the output (1 micro Farad) to block the DC offset. By my understanding this will give me the AC signal shifted down to +12V to -12V as long as I do the Darlington pair part right is this correct?
My second question, how do I actually use the Darlington pair to amplify but not distort my signal? Should I be looking at something different for amplifying the signal?
Sorry if this seems very simple but I'm looking for someone with know how to point out if I've made any blindingly obvious mistakes this far.
Thanks for any help!
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