[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
> 
> Piensa en Bits SA de CV
> 
> 
>  
> 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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