[time-nuts] Power supply for time source concerns

[Taka Kamiya]

Yes.....
I considered float charging a battery bank and switching power supply + linear regulator combination as well.  

Concern with the first is safety in charging.  I was intending to use GEL cell lead acid battery.  24V chargers are plentiful but there is no telling what they actually do.  Adding a series regulator won't work because of the required voltage drop with most of the 3 terminal kind.  I still want to try this as it will double as UPS as well.

Switcher + linear regulator sounds promising.  One unknown is, how much high frequency ripples/noises those regulators actually remove.  I guess I'll just have to try this out.  Ferrite sleeves, low pass filters, chokes, etc, etc, etc are under consideration.
I have a very nice lab grade switching power supply but unfortunately, this stupid thing resets to ZERO every time power cycled and starts up in current limiting mode.  Meaning if I forget to switch modes, it can go as high as 60 volts.  By then, all devices are GONE!
My main usage will be just for time standard for my lab.  Stable 10MHz and 1 pps is all I need to sync everything up.  I am not going to multiply output to GHz range or do anything else exotic.  I wonder how much ripple will actually affect?  


--------------------------------------- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

    On Sunday, December 22, 2019, 6:00:32 PM EST, jimlux <jimlux at earthlink.net> wrote:  
 
 On 12/22/19 1:18 PM, Poul-Henning Kamp wrote:
> --------
> In message <1958104416.2586171.1577043445646 at mail.yahoo.com>, Taka Kamiya via t
> ime-nuts writes:
> 
>> First question to the group is, how do YOU manage this problem?
> 
> It used to be that there were only one kind of switching power-supply: The noisy ones.
> 
> That is no longer true by definition, but there is no easy road to this particular Damascus.

My strategy is DC/DC converter to get close, and high PSRR LDO linear 
regulator to the final voltage. Close attention to the DC/DC converter 
input and output so you don't couple to the ultimate output through 
radiated or parasitic conducted paths.

The LT3042 series regulators have high PSRR, are available with negative 
voltages now, and can be paralleled for more current capacity.

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