MOV vs diode?

[grungymike]

Was wandering around in my beginner's bible (Practical Electronics for Inventors) and came across something that got me to wondering...

The Hammerhead circuit uses a pair of 1N4148 diodes for clamping in front of the 1st op-amp. This limits the signal voltage to approx .6V max.

Has anyone tried using MOV's (metal oxide varistor) instead of diodes?
I haven't researched it yet, but they apparently come in a variety of breakdown voltages, according to what I've read so far. I've still gotta read up on the NE5534 specs and see what the max acceptable signal voltage is.

Same question applies re. zener diodes...

If these things worked, they could allow for a stronger signal into the 1st op-amp, hopefully permitting a less radical gain ratio.

gm

[w5cdt]

Was wandering around in my beginner's bible (Practical Electronics for Inventors) and came across something that got me to wondering...

The Hammerhead circuit uses a pair of 1N4148 diodes for clamping in front of the 1st op-amp. This limits the signal voltage to approx .6V max.

Has anyone tried using MOV's (metal oxide varistor) instead of diodes?
I haven't researched it yet, but they apparently come in a variety of breakdown voltages, according to what I've read so far. I've still gotta read up on the NE5534 specs and see what the max acceptable signal voltage is.

Same question applies re. zener diodes...

If these things worked, they could allow for a stronger signal into the 1st op-amp, hopefully permitting a less radical gain ratio.

gm

MOV's are typically used to protect against damaging voltage spikes. You will find that while an MOV can absorb more energy than a 1N4148 they also have a *lot* of capacitance. Much more than the 5pF of a 1N4148. So unless you are using them in some sort of "power" circuit I think you will be disappointed with an MOV.

-CT