Barry, 

I have recently purchased some DC supply components from Newark
and Jameco: 

Newark:	83F9250	Dual DC-DC, +,- 15V, 67ma, 12-18Vin	$14.47
		83F9256	Single DC-DC, +15V, 133ma, 12-18Vin	$14.47
(Many other 2-watt options are available, like 12 Vout at higher I;
 I then further regulate the +,- 15 V to +,-12, to 0.001%.)
(I use a AC-DC wall-brick for the raw DC source.)

Jameco has the DATEL 3-watt "BWR-15/100 D12" DC-DC supply: 12Vin, 
+,- 15Vout, at 100ma, Cat# 155782, for $7.25 (usually about $40
from Newark)

Also a collection of AC/DC wall modules, like #129331, 12V,800ma
output, $6.95. They also have lower I for as low as $4, so use two.
(Jameco: 1 800 831 8242)

These last two will let you make a well (0.1%) regulated supply
for under $15. Regulation at 0.1% is adequate for most seismic 
amplifiers, but better stability is needed for a fedback instrument.
The DATEL unit is 3cm x 2cm x 1cm high.

Regards,
Sean-Thomas
!p

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