Simple oscillator circuit
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From: Gone Fishin' on 6 Apr 2010 00:24 I want a simple oscillator circuit that will give 30 kilohertz. <http://tinypic.com/m/9quype/3> Which of these components do I change to achieve this? What values should these be? If I want a little variance (~10 percent) it should be the resistor, right? What other opamps can I use? Thank you.
From: Sjouke Burry on 6 Apr 2010 00:45 Gone Fishin' wrote: > I want a simple oscillator circuit that will give 30 kilohertz. > > <http://tinypic.com/m/9quype/3> > > Which of these components do I change to achieve this? > > What values should these be? > > If I want a little variance (~10 percent) it should be the resistor, right? > > What other opamps can I use? > > Thank you. > The opamp needs to be able to feed the lamp, so you need a high-output one. Then bild it, check frequency against the value of C, change C accordingly. The lamp makes sure of a stable output without distortion.
From: Phil Allison on 6 Apr 2010 02:07 "Gone Fishin'" >I want a simple oscillator circuit that will give 30 kilohertz. > > <http://tinypic.com/m/9quype/3> > > Which of these components do I change to achieve this? > > What values should these be? ** The formula for frequency is: f = 1 / 2.pi.R.C So with the values shown, oscillation is at 159 Hz. Change both R values and both C values together and do not go under 1kohm for R. Many other op-amps could be used, but the NE5534 is a good choice. ..... Phil
From: Gone Fishin' on 6 Apr 2010 02:18 > The opamp needs to be able to feed the lamp, so you need a > high-output one. Then bild it, check frequency against the value > of C, change C accordingly. > The lamp makes sure of a stable output without distortion. I calculate 50pF with 100K gives 31.8KHz. But which of the C do I change? The one connected to ground? Which of the R is part of the RC circuit? (The circuit is a bit confusing because it uses 2 identical R & C values.) If I want to make the RC variable, which R do I replace with a pot (or fixed + pot)? Also, this op amp (LF155) is specified as dual-supply type. I need a single supply op amp. Will the R-C connection to ground of this circuit be connected to -Vcc regardless if it is a single or dual supply op amp? Thank you.
From: Gone Fishin' on 6 Apr 2010 02:20
> Change both R values and both C values together and do not go under 1kohm > for R. > > Many other op-amps could be used, but the NE5534 is a good choice. > > > > .... Phil Thanks for your reply Phil. So changing both R to 50pF and leaving both R at 100K will give 31.8KHz? |