[time-nuts] newbie question Thunderbolt supply
EWKehren at aol.com
EWKehren at aol.com
Sun Aug 26 10:46:40 UTC 2012
Having played with several solutions I found the best is a 12 V 1 A
switcher with the output voltage increased to 15 V, check the capacitors and if
necessary replace with 25 V. I laid out a PC board that has a TC7662A
inverter followed by a 79L12. Also on the board is a 7812 followed by a 7805.
Putting them in series gives me good thermal distribution. In my opinion every
thing else is an overkill.
Working with very low noise PLL's I have found that getting rid of switcher
noise is much easier than 60 Hz.
There are other pin compatible alternatives to the TC7662A, even a 555 will
work, just more components.
Bert Kehren
In a message dated 8/25/2012 8:10:07 P.M. Eastern Daylight Time,
lists at rtty.us writes:
Hi
The easy way to do a TBolt supply is to start with something between 15
and 18 volts. Regulate down to 12 and 5 with linear regulators. 7805's are
fine for the +5. Something like a LT1764 might be better for the +12. The
-12 supply is very low current and does not matter much. People have had good
luck with voltage inversion chips off the +15 and then something like a
79L12.
Bob
On Aug 25, 2012, at 6:41 PM, Edgardo Molina <xe1xus at amsat.org> wrote:
> Dear Chris,
>
> Good afternoon. I am in the process of mounting my TBolt to a 2U 19"
rack enclosure and was looking for a decent power supply. I found the Cisco
unit and I am ordering a couple of them just in case. It would really be nice
if I could have access to the diagram of the upgrade you did on yours to
recreate the same performance from the Cisco unit. Please do not feel
compromised if it is difficult to share. I didn't mean to be rude and if my note
causes you any discomfort please kindly disregard it. I jumped into the
thread because of experiencing the same doubts as the originator of it.
>
> Redondo Beach? I love visiting there whenever visiting my brother who
lives in Rancho Palos Verdes. I would invite you lunch anytime just for the
pleasure of meeting you in person.
>
> Thank you.
>
> Regards,
>
>
>
>
>
> Edgardo Molina
> Dirección IPTEL
>
> www.iptel.net.mx
>
> T : 55 55 55202444
> M : 04455 20501854
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> Piensa en Bits SA de CV
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> Información anexa:
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> On Aug 25, 2012, at 3:26 PM, Chris Albertson <albertson.chris at gmail.com>
wrote:
>
>> On Sat, Aug 25, 2012 at 1:06 PM, Jerry <jsternmd at att.net> wrote:
>>
>>> I am using a Cisco supply 3 voltage supply for the T-bolt. Is there
any
>>> performance loss if the +12vdc rail and the -12vdc rail are off by a
few %
>>> in opposite directions, e,g +11.7 vdc and -12.3vdc ?
>>>
>>> The true nuts here on the time nuts list will tell you that the noise
from
>> a switching power supply is bad and that you need a regulated linear
power
>> supply. But for most practical purposes the Cisco supply is a good
one.
>> Being only slightly nuts myself. I use the Cisco supply but I built a
>> small power adaptor board with matching connectors and some "pi"
filters
>> made with RF choke and capacitors. I realy don't thing the filters are
>> needed but I wanted a connectorized installation and a small choke was
as
>> easy to solder in as a length of wire.
>>
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
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