Re: Function Generator Output Impedance

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Bart,

All nice signal generators are based on 50 ohms output impedance.  This
protects the generator and allows the use of 50 ohm coax and 50 ohm loads to
keep signal integrity.  Not good for running "real power" however.  For that
you need an amplifier.  Audio amps usually roll off outside the 20-20kHz range
and the ones that don't are expensive.  Running audio amps under power at
~200kHz usually blows them up but big power ICs like the LM12CLK will do fine.

See the files describing my low-Z amplifier at:

http://hot-streamer-dot-com/TeslaCoils/Misc/Low-ZAmp/

It's just an LM12CLK unity gain amp.  Be careful of ground loops (single point
ground) and the other cautions in the data sheet.  It goes from DC to 500kHz
and has about 1/2 ohm of impedance at the higher frequencies.

I think it cost about $100 with all nice new parts.  I run my Agilent 33120A
into it and it works real well.  If you have questions about running into some
odd load let me know and I'll be sure it works. I use mine for Tesla coil stuff
that needs a low-Z drive signal and it works great.

Cheers,

        Terry



At 11:22 PM 2/26/2002 +0000, you wrote: 
>
> Hi All, 
>
> Question: 
> While looking for low output impedance generators, I keep running across 50
> ohms which appears to be typical. Are there lower output impedance
> generators? Are there methods to reduce a typical 50ohm output impedance
> generator down to near zero ohms? 
>
> Thanks, 
> Bart