Product of Two Voltage Sources

[jabers]

Hello

Is it possible to combine voltage sources in such a way that their equivalent voltage is the product of their two individual voltages?

 

[KeepItSimpleStupid]

Yes, but don;t expect to draw any power from it. Look up "Analog Multiplier" or "4 quadrant multiplier"

 

[dougy83]

If by "product" you mean "multiply", then no.

If by "product" you mean "some function of", then yes. If you connect the voltage sources in series you will get an output voltage that is the sum of the two voltage sources. If you connect them in parallel through two equal series resistances, then the output voltage will be half-way between the two voltage source voltages.

What are you trying to achieve, if anything?

 

[jabers]

Ok, thanks. I'm new to EE. I was just thinking about amplitude modulation. I wanted there to be a way to combine a modulating signal and a carrier signal simply by connecting their sources in a particular way.

 

[dougy83]

Ok. AM uses multiplication, so you'll have to use some active element, e.g. a transistor.

 

[crutschow]

If by "product" you mean "multiply", then no.

...................

Why do you say that? An analog multiplier does have an output that is the product of two signal voltages.

 

[dougy83]

Why do you say that? An analog multiplier does have an output that is the product of two signal voltages.

Because I thought he wanted to combine two voltage sources, not pass them through a multiplying circuit.

 

[Norator]

You could use a voltage controlled oscillator, a V-F convertor. One I did used three opamps but there might be a simpler way depending on the freqs involved.

 

[jabers]

back to the drawing board

 

[crutschow]

Because I thought he wanted to combine two voltage sources, not pass them through a multiplying circuit.

After re-reading his post, I believe you are correct.

Edit: On second thought, he stated in post #4 that he was interested in amplitude modulation. For that an analog multiplier will work.

 

[ccurtis]

Hello

Is it possible to combine voltage sources in such a way that their equivalent voltage is the product of their two individual voltages?

One possible way is to suppose we have an amplifier, then Vout of the amplifier is equal to Vin1 of the amplifier times the gain G of the amplifier (Vout=Vin1 * G). Now suppose the gain of the amplifier is controlled by a voltage Vin2, such that G=Vin2. Substituting Vin2 for G in the first equation gives, Vout=Vin1 * Vin2. Note that the gain of the amplifier need not be >= 1 (i.e. it could also be a voltage controlled attenuator).