Voltage changes and MOSFETs

[GT Blocker]

Hey there Folks;

I have a question.

I am replacing the 7660 with a virtual ground IC. To do so, I need to step up to 22vdc or better.

The question is:

How will a 22v+ pulse (as opposed to my current 11+v lithium) affect the coil output (and, for that matter, any other parameters)?

I am running what should be a more than adaquate CREE CMF10120 silicon carbide MOSFET.

(http://www.cree.com/~/media/Files/Cr.../CMF10120D.pdf)

Any thoughts?

Thanks,
GTB

[mickstv]

If this is relation to the HH detector, the idea of having a virtual GND circuit to run the op-amps wont work if you plan on running the TX on 22 volts as well. The TX will need to be kept at 11 volts, because 11 volts will be common GND for the op-amps.


Why the need to change to a VG system ?

[GT Blocker]

Hey there, mickstv;

"If this is relation to the HH detector, the idea of having a virtual GND circuit to run the op-amps wont work if you plan on running the TX on 22 volts as well. The TX will need to be kept at 11 volts, because 11 volts will be common GND for the op-amps."


My 'HH' detector is well modified. The coil is seperated from the processing circuitry and thus runs on the original pws (i.e. 11v, 22v, whatever). The virtual ground has nothing to do with the coil voltage pulse. The associated digital and analog circuits are a result of the virtual ground, which is derived from the coil supply voltage (just as in the original HH). The result is far less noise on my amp pws. The 7660 injects quite a bit of supply noise that I can do quite well without.

The problem is that I need to feed the coil 22+v to derive my +/-pws virtual gnd. to make the rail to rails.

The original question is...was...what is the impact of raising the initial coil voltage with all else remaining the same?

GTB

[ODM]

With a higher voltage the coil current will rise more rapidly, giving a higher current and higher flyback voltage for a similar coil and excitation pulse length.

Short version: Faster targets (smaller L and larger R) are more easily excited by a short pulse while slower ones (larger L and smaller R) will require a longer pulse duration for full excitation. Ground response has several threads of its own.

If you like mods, how about dual voltage or bipolar pulsing, or a constant current limiter for consistency? Solid dual supplies will give you lots of leeway.