[GPS_Standard] -5 to +5 Voltage Source

[Zack Widup]

The VE2ZAZ design includes a 5 volt positive regulator on the circuit board.

To get a negative 5 volts I've used the simple 7660, etc. design that
just requires a few capacitors. Positive 5 volts in (brought from the
7805 on the circuit board) produces -5 volts out. The current demand
for this circuit is well within the specs of a 7660 or a 7662. I have
some other circuits that will supply quite a bit more current at
negative 5 volts. I think the TC962 is one device. The LT1072/1172 is
another.

73, Zack W9SZ


On 12/13/14, Dave Platt <dplatt at radagast.org> wrote:
>
>> 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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