Anybody want a Thunderbolt power supply?
A little board to generate -12 and +5 from a 15 watt 12 VDC input wouldn’t be too hard to design. If I put one out for $25, would anyone like one?
I would be interested, I think. Planning ahead for if the one I have for my Thunderbolt fails, I guess. Are there different models or would a photo of the input ports on mine be useful?
PS: Funny running into you here! :)
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Nick Sayer via time-nuts
Sent: Tuesday, 30 August, 2016 20:23
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Subject: [time-nuts] Anybody want a Thunderbolt power supply?
A little board to generate -12 and +5 from a 15 watt 12 VDC input wouldn’t be too hard to design. If I put one out for $25, would anyone like one?
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and follow the instructions there.
If low noise, that would simplify things here.
Dave
-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf
Of Nick Sayer via time-nuts
Sent: Tuesday, August 30, 2016 19:23
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Anybody want a Thunderbolt power supply?
A little board to generate -12 and +5 from a 15 watt 12 VDC
input wouldn't be too hard to design. If I put one out for
$25, would anyone like one?
time-nuts mailing list -- time-nuts@febo.com
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
I use the TAPR HPSDR LPU:
< https://www.tapr.org/kits_lpu.html >
I run two Trimble Thunderbolts on a LPU that uses the house 13.6
Volt supply that is backed up with two 6 Volt golf cart
batteries in series. I didn't bother installing the Anderson
Power Pole and ATX connectors, but wired directly to the circuit
board.
Mike - AA8K
On 08/30/2016 10:23 PM, Nick Sayer via time-nuts wrote:
A little board to generate -12 and +5 from a 15 watt 12 VDC input wouldn’t be too hard to design. If I put one out for $25, would anyone like one?
time-nuts mailing list -- time-nuts@febo.com
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and follow the instructions there.
If onen is going to use a dc-dc converter the Cuk converter used here is a nice topology in that it can have low input and output ripple currents. However input and output filters like the Murata BNX002/BNX005 series would have been useful as would an LM3042 linear post regulator for the -12V output.. Low noise regulators for the +12V and +5V outputs would also be useful.
Bruce
On Thursday, 1 September 2016 11:48 AM, Mike Naruta AA8K <aa8k@comcast.net> wrote:
I use the TAPR HPSDR LPU:
< https://www.tapr.org/kits_lpu.html >
I run two Trimble Thunderbolts on a LPU that uses the house 13.6
Volt supply that is backed up with two 6 Volt golf cart
batteries in series. I didn't bother installing the Anderson
Power Pole and ATX connectors, but wired directly to the circuit
board.
Mike - AA8K
On 08/30/2016 10:23 PM, Nick Sayer via time-nuts wrote:
A little board to generate -12 and +5 from a 15 watt 12 VDC input wouldn’t be too hard to design. If I put one out for $25, would anyone like one?
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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Bruce wrote:
Low noise regulators for the +12V and +5V outputs would also be useful.
Very true. By focusing on the -12v supply, I did not intend to suggest
that low noise is unimportant on the +12v and +5v supplies.
The suggestion to use LT3042s is a good one, but note that it has an
output current rating of 200mA. The Tbolt needs ~250mA at +5v, and
~700mA at +12v [at startup -- but only ~150mA steady-state, depending on
ambient temperature]. LT3042s can be used in parallel, so two of them
for the +5v supply and four of them for the +12v supply would be
required. That isn't so bad for the +5v supply, but seems excessive for
the +12v supply (particularly when three of the four are needed only
during warmup from cold).
The LT3088 and LT3080 will deliver 800mA and 1.1A, respectively, with
low noise (but not as low as the LT3042). One of those might be a
better choice for the +12v supply. Similarly, the LT3085 can deliver
500mA, so one of those could be used for the +5v supply.
Finally: Linear Technology -- Where is our negative-voltage complement
to the LT3042?
Best regards,
Charles
Just split the 1uF coupling cap into 2x 2u2 in series in the Cuk dc-dc converter add a 1:1 transformer (should be small at 2MHz) between the pair of 2u2 caps to produce a floating output and use an LT3042 as a post regulator.With a mains transformer input supply a separate isolated winding for the -12V allows an LT3042 to be used for the negative regulator.
I have a quad LT3042 PCB that I must get around to assembling.One potential issue with the LT3042 is the relatively high noise at low frequencies when the capacititve bypassing of the resistor that sets the output voltage is ineffective.
Bruce
On Thursday, 1 September 2016 3:37 PM, Charles Steinmetz <csteinmetz@yandex.com> wrote:
Bruce wrote:
Low noise regulators for the +12V and +5V outputs would also be useful.
Very true. By focusing on the -12v supply, I did not intend to suggest
that low noise is unimportant on the +12v and +5v supplies.
The suggestion to use LT3042s is a good one, but note that it has an
output current rating of 200mA. The Tbolt needs ~250mA at +5v, and
~700mA at +12v [at startup -- but only ~150mA steady-state, depending on
ambient temperature]. LT3042s can be used in parallel, so two of them
for the +5v supply and four of them for the +12v supply would be
required. That isn't so bad for the +5v supply, but seems excessive for
the +12v supply (particularly when three of the four are needed only
during warmup from cold).
The LT3088 and LT3080 will deliver 800mA and 1.1A, respectively, with
low noise (but not as low as the LT3042). One of those might be a
better choice for the +12v supply. Similarly, the LT3085 can deliver
500mA, so one of those could be used for the +5v supply.
Finally: Linear Technology -- Where is our negative-voltage complement
to the LT3042?
Best regards,
Charles
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Getting the required Thunderbolt supply rails from a nominal 12v dc supply
of doubtful cleanliness is an issue that also needs to be addressed. I'm
still mulling over that one. (and using a triple output switcher from an
inverter backed mains supply meantime!)
The ex-telco GPSDOs all run on a nominal 24-50 volt DC supply but I don't
know how they generate their internal supplies. I suspect switchers?
DaveB, NZ
----- Original Message -----
From: "Charles Steinmetz" csteinmetz@yandex.com
To: time-nuts@febo.com
Sent: Thursday, September 01, 2016 3:35 PM
Subject: Re: [time-nuts] Anybody want a Thunderbolt power supply
Bruce wrote:
Low noise regulators for the +12V and +5V outputs would also be useful.
Very true. By focusing on the -12v supply, I did not intend to suggest
that low noise is unimportant on the +12v and +5v supplies.
The suggestion to use LT3042s is a good one, but note that it has an
output current rating of 200mA. The Tbolt needs ~250mA at +5v, and ~700mA
at +12v [at startup -- but only ~150mA steady-state, depending on ambient
temperature]. LT3042s can be used in parallel, so two of them for the +5v
supply and four of them for the +12v supply would be required. That isn't
so bad for the +5v supply, but seems excessive for the +12v supply
(particularly when three of the four are needed only during warmup from
cold).
The LT3088 and LT3080 will deliver 800mA and 1.1A, respectively, with low
noise (but not as low as the LT3042). One of those might be a better
choice for the +12v supply. Similarly, the LT3085 can deliver 500mA, so
one of those could be used for the +5v supply.
Finally: Linear Technology -- Where is our negative-voltage complement to
the LT3042?
Best regards,
Charles
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Dave wrote:
Getting the required Thunderbolt supply rails from a nominal 12v dc
supply of doubtful cleanliness is an issue that also needs to be
addressed. I'm still mulling over that one. (and using a triple output
switcher from an inverter backed mains supply meantime!)
The ex-telco GPSDOs all run on a nominal 24-50 volt DC supply but I
don't know how they generate their internal supplies. I suspect switchers?
Yes, they typically have two or three flat-pack DC-DC converters inside.
I have converted a number of them by replacing the DC-DC converters
and feeding the circuitry from a mains-operated linear DC supply
(usually because one or more of the DC-DC converters was fried and I saw
it as a golden opportunity rather than a problem of locating spare
converters of invariably questionable provenance).
Best regards,
Charles
Am 01.09.2016 um 05:35 schrieb Charles Steinmetz:
The suggestion to use LT3042s is a good one, but note that it has an
output current rating of 200mA. The Tbolt needs ~250mA at +5v, and
~700mA at +12v [at startup -- but only ~150mA steady-state, depending
on ambient temperature]. LT3042s can be used in parallel, so two of
them for the +5v supply and four of them for the +12v supply would be
required. That isn't so bad for the +5v supply, but seems excessive
for the +12v supply (particularly when three of the four are needed
only during warmup from cold).
I have made a stamp-sized layout for LT3042 + external npn power transistor
as shown in the data sheet.
Not fabricated, let alone tested.
The LT3088 and LT3080 will deliver 800mA and 1.1A, respectively, with
low noise (but not as low as the LT3042). One of those might be a
better choice for the +12v supply. Similarly, the LT3085 can deliver
500mA, so one of those could be used for the +5v supply.
Finally: Linear Technology -- Where is our negative-voltage complement
to the LT3042?
Yes, that is badly missing.
regards, Gerhard
