V/F converters, current amplifiers, and display counters

[mooney@oxygen.aps1.anl.gov (Tim Mooney)]

Dear folks,

   We've been talking to a potential vendor of V/F converters, and would like
to know how much interest there is in the following product:

NIM module containing four V/F converters
Input:		0 - 10V
Output:		0 - 100 kHz
Nonlinearity:	<= 0.05%
Price:	$800/module + nonrecoverable engineering costs (<20 modules)

SRI-CAT is likely to order 15 (one per experimental station, plus a few
spares.)  If APS as a whole can absorb a volume of 50, the price per
unit would drop further from what I believe is already a reasonable figure.

While I'm on the subject, here's our tentative plan to support
beam-current integration from ionization chambers: We expect to use a
Stanford Research Systems SR570 current amplifier to feed one channel
of the V/F converter, and count the V/F output with a scaler.  We
expect to control the SR570 via its RS232 port, and implement some kind
of auto-zero support in EPICS.  If anyone has found a markedly better
solution, or a less expensive current amplifier of comparable quality
(the SR570 costs $1895) I'd like to hear about it.  At one point we
talked about getting the V/F built into the current amplifier, but
several of us want free-standing V/F as well.

Also, I've been talking to Joerger about their Quad Visual Scaler,
which they are willing to re-engineer into a useful rack-mount display
for beam current, etc., if sufficient interest can be aroused.  If any
of you are interested, please let me or Fred Joerger know.  I told him
we have to have several time bases, and a display that stays visible
while the next value is being counted, but I've so far let him off the
hook on separate time bases for each counter.

Eventually, detailed specs for these devices could be considered by the
hardware subgroup of the BCC, but I would like to get anticipated
volume information now, so the vendors can allocate design time, and
make credible cost estimates, and so we can know whether to involve the
BCC at all.  (If there is little general interest, we'll just determine
specs ourselves and place orders.)

Tim Mooney