[time-nuts] newbie question Thunderbolt supply

Bob Camp lists at rtty.us
Sat Aug 25 20:09:12 EDT 2012


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
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> Piensa en Bits SA de CV
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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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