# how to this build this circuit which uses oscillator and amplifier

#### PG1995

Joined Apr 15, 2011
816
Hi

It would really kind of you if you could help me to build the circuit which does what has been explained in the linked diagram below. I'm new this stuff. Have never used oscillator or an amplifier. If you want to change some parameter to make the circuit simple, then you can. Thank you.

the diagram: http://img89.imageshack.us/img89/3427/invercrkt.jpg

Best wishes
PG

PS: I just made that block diagram up. You could any other frequency instead of 5 Hz. Thank.

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#### praondevou

Joined Jul 9, 2011
2,942
You will need an oscillator e.g. like THIS
If you want to use an PWM-inverter that's also possible but the circuit will become MUCH bigger.

Then you need a fullwave rectifier e.g. like THIS (pic 12.37)

After this you pass the signal through a non-inverting amplifier, with an opamp for example. Yes the amplifier could also "de-amplify", if it's gain is set to less than 1.

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Joined Dec 26, 2010
2,148
It may help to begin by sorting out a bit of terminology: The word "inverter" generally means a device for turning DC into AC, usually working at a relatively high power level. This is the kind of thing that might be used to power AC equipment from a storage battery during a power cut. A device which only produces a low-level AC signal (for instance used to drive an amplifier) would normally be called an oscillator. Power inverters do not usually consist of an oscillator followed by a linear amplifier: such an arrangement is possible, but would not be very efficient.

In your block diagram, your oscillator appears to be producing something like an un-smoothed full-wave rectified DC signal (at 5hz!!!), which is then amplified two times. This seems an odd requirement: do you really want this, or did you just make it up at random?

1) To do this with analogue circuitry would require something like a Wien bridge or phase-shift oscillator, to give you as a sine wave. Inductors and transformers get difficult at such low frequencies, so LC oscillators are probably out of the question. Note that at such a low frequency as 5Hz, you will probably not be able to use the little light-bulb sometimes suggested as a level stabiliser.

A precision rectifier circuit using op-amps would probably fit the bill for rectifying the sine-wave. This link may give you some ideas:

http://www.physics.udel.edu/~nowak/phys645/More_opamp_circuits.htm

2) A feedback amplifier can be designed to have a voltage gain of less than one. http://www.electronics-tutorials.ws/opamp/opamp_5.html

#### PG1995

Joined Apr 15, 2011
816