[GPS_Standard] -5 to +5 Voltage Source

[w0ep at w0ep.us]

I forgot, my GPS unit required +3 VDC, so I have
a regulator making that also.



Chris

-------- Original Message --------
Subject: RE: [GPS_Standard] -5 to +5 Voltage Source
From: <w0ep at w0ep.us>
Date: Sun, December 14, 2014 2:21 pm
To: "Mark Fancher" <mark.fancher at twc.com>, gps_standard at mailman.qth.net



I am using that one.  It is working well.



Besides the VE2ZAZ board, the oscillator requires a heater
voltage and an oscillator voltage.


So, in my GPSDO I have supplies for +24, +12, +5 and -5.
You can run without the +5 if you let the controller board
produce that for you.  You can run without the -5 if
you want to go with the plan Dave described of using 
half of the control voltage swing.


I start with a +24 (spec calls for anywhere between +20 and +30)
supply and use regulators to get the +12 and +5.
Then I have another supply that produces -5.


The manual for that oscillator is available at:


http://www.leapsecond.com/museum/10811a/10811a.pdf









  -------- Original Message --------
 Subject: Re: [GPS_Standard] -5 to +5 Voltage Source
 From: "Mark Fancher" <mark.fancher at twc.com>
 Date: Sun, December 14, 2014 5:35 am
 To: <gps_standard at mailman.qth.net>
 
 I guess I should have planned better before I bought the 10811
oscillator.
 I thought these were very popular for these GPSDO projects, but didn't
know
 there'd be so much difficulty in providing the adjustment voltage to
it.
 
 What oscillator is best for the VE2ZAZ board that hopefully won't
require
 the complex external negative voltage scheme?
 
 Mark
 
 -----Original Message-----
 From: GPS_Standard [mailto:gps_standard-bounces at mailman.qth.net] On
Behalf
 Of Dave Platt
 Sent: Saturday, December 13, 2014 10:11 PM
 To: gps_standard at mailman.qth.net
 Subject: Re: [GPS_Standard] -5 to +5 Voltage Source
 
 
 > I'm having difficulty understanding how to create the proper voltage 
 > source for the VE2ZAZ control board, -5 to +5 volts. Any suggestions?
 
 There are several approaches.
 
 If you start with a single-voltage supply (say, a +12 or +24 - whatever
your
 oscillator requires) you can add an additional regulator to get a clean
+5
 supply for the board's oscillator-control output. Since you only need a
 small current, a simple 78L05 regulator and a couple of filter caps
would be
 all you need.
 
 The -5 is more difficult. The most straightforward way is to use a
 commercially-made or home-made power supply with both positive and
negative
 outputs... say, a +/- 15 (these are relatively common) and then use a
 negative voltage regulator such as a 7905 to regulate the -15 down to
-5.
 
 You could buy a kit such as the Chaney C6895 from Electronics
Goldmine...
 this has three variable output voltages (positive and negative up to 15
 volts, at 400 mA, and positive up to 21 volts at 1 ampere). This might
be
 your best bet, if 1 amp is enough to run the oscillator with its heater
and
 the main VE2ZAZ input - the two low-current outputs could be set to +5
and
 -5 and provided to the VE2ZAZ output circuit.
 
 It *is* possible to start with a single-voltage DC supply, and generate
 positive and negative voltages from it. It's a bit tricky. One approach
is
 to use a switching-type "inverting regulator" to create the negative
 voltage. Alltronics has a +12 in, -5 out (Astec AA7600), $8 for two.
These
 switching inverters might not be a great solution for a GPSDO where you
want
 really low noise, though.
 
 Another approach is to start with something like a 24-volt DC supply,
and
 use a 7805 linear regulator to create an "artificial ground" (which
then
 becomes the "GND" power input to your VE2ZAZ board).
 
 If I were you I'd probably look for a multiple-output DC power
supply...
 Electronics Goldmine, Alltronics, All Electronics, Marlin P Jones are
all
 good on-line vendors to check.
 
 And... as an out-of-the-box possibility - although your HP oscillator
has a
 -5 to +5 tuning range, there's no law that says you have to actually
*use*
 the whole tuning range. You could have the VE2ZAZ board put out a
tuning
 voltage between 0 and 5 (so no negative supply
 required) and use the HP oscillator's "FREQ ADJUST" trimmer to
rough-tune
 the oscillator so that it's right about on-frequency when the VE2ZAZ is
 feeding a mid-scale output (2.5 volts) to the oscillator's EFC input.
 
 This would let you get away with just positive power supply voltages to
the
 oscillator oven, oscillator input, and VE2ZAZ.
 
 
 
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