Re: Waveform Generators - Any interest in BULK board / enclosure purchase ? ? ?

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Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 


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From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, May 01, 2004 4:12 PM
Subject: Waveform Generators - Any interest in BULK board / enclosure
purchase ? ? ?


 > Original poster: "Eastern Voltage Research Corporation"
<dhmccauley-at-easternvoltageresearch-dot-com>
 >
 > I've been thinking about designing a high quality waveform generator for
 > sometime now and wanted to find out
 > if there is any interest on the group for possibly a bulk board / front
 > panel purchase.
 >
 > Basically, I would propose designing a PCB board and also a customized
front
 > panel (to fit a nice off-the-shelf Hammond enclosure box) and sell them
 > together.
 >
 > The function generator would basically have:
 > Sine Wave
 > Square Wave
 > Triangle Wave
 > Pulse (adj Duty)
 > Sawtooth Wave
 >
 > Initially 0-5VDC with adjustable OFFSET output with the possibility of
going
 > with a power stage for high voltage output.
 > It would also be PLL synthesized with a crystal for high accuracy and
 > possibly an LCD PIC interface.
 >
 > I haven't made any decisions on whether i'll do this or not, but if there
is
 > enough interest, i may consider pursuing it.
 >
So what you're thinking of is something like an HP3325? (available surplus
for <$500)

High accuracy can come from ways other than PLLs.  You could have a crystal
timebase counter and an ordinary voltage tuned oscillator, for instance,
unless you need to have the frequency controlled by computer.  In the latter
case, a strategy with a 16,18, or 24 bit DAC driving the VCO (openloop) and
a counter, with software to "close the loop" might actually work better.

One can buy inexpensive 2MHz function generators with a crystal timebase
counter for a couple hundred dollars, brand new.

On the other hand, if you need to phase lock it to an external reference
(not just have high frequency accuracy), then a PLL might be needed.

If you don't need anything more than a few tens of kHz, a PC sound card
makes a dandy ARB, for free, although response doesn't go down to DC.

Now, if you want high voltage, that's another story entirely.