Mohican question, capacitors.

[Dave Frederickson]

Geoff,

I see no reason why the 100 MHz probes shouldn't work. Just remember to compensate the probe by connecting it to one of the CAL terminals and adjusting the variable cap in the probe connector, usually visible through a small hole, until the square wave corners are square and not rounded.

Regarding the speaker with 34 ohms of impedance, adding a resistor won't accomplish your goal. What might work is to add an inductor which together with the impedance of the speaker will total 34 ohms.

To help, the formula for inductive reactance X(L) = 2 * PI * f * L, where L is the inductance of the speaker coil and f is 400Hz, the frequency at which speaker impedance is calculated.

The impedance, Z, is SQRT(R^2 + X(L)^2) where R is the DC resistance of the inductor or coil.

Yes, it does look like the formula for the hypotenuse of a triangle, because the DC component is one side, the AC component is the other side, and the impedance is the hypotenuse.

I think.

Dave