>From I know from measuring voltage references getting linearity in those
kinds of temp ranges not only requires really good sensors but often it
needs to be thermally bonded to what's being measured and often with some
block of material that's makes swings in temperature much more subtle.
Even a
Good evening TGIF!
You've all given me some great ideas. I'm a computer scientist so tell me
what's wrong with this?
Can't I just use a high quality APC backup power system like we use to
power racks of gear in our Telco and compute closets? A good one runs the
full AC load the rack runs on.
On 9/25/20 5:50 PM, Mark Goldberg wrote:
Those look pretty good compared to some I got. See attached.
I'm purchasing a small, custom frequency run and it is cheaper for me to
super select than for the manufacturer to do so. In fact, they won't set up
that kind of testing for such a low volume.
It would appear that the HP 3456A in temperature mode would meet your needs.
The 5k thermistor is very cheap. The temperature resolution is very small, as
I recall perhaps 0.001 degree but not sure. You can log manually or via GPIB.
Don't think its accuracy is anywhere near its resolution
For what it is worth I ran two identical AGM 12 volt batteries for approx 7
years or so in my home lab.
I carefully adjusted the terminal voltage while float charging them via a
blocking diode and checked the voltage every few months. I also confirmed
that the terminal voltage of each 12
I've got a collection of 1-wire gizmos and USB thumb drives. They are great
for many applications but I'm looking for something better/different.
I'd like something that reads to 0.01 degree or 0.001 degree. I don't need
accuracy. What I want is reasonable linearity so I can make pretty
Hi folks.
I'm new to the board, my name is Patrick. I'm a career RF/systems engineer.
Greetings all around!
I just made a couple of 'good' handyman special buys on the worlds largest
auction. I got a PRS10 that needed a new SA612A mixer that I got working,
so, happy about that. Thanks to KO4BB
When I was still RVing and wanted an electrically quiet charger I built my own
"smart charger: using the guts of an Astron 35A linear power supply with an
added uc3906 based controller. I later replaced it with a higher efficiency
Iota 30A supply with an IQ4 charge controller. It doesn't hurt
Larry McDavid writes:
> Yes, it would be nice to have a Powerpole option for the Mini-Box
> Y-PWR-Hot-Swap-Load-Sharing-Controller identified below, but it would be
> even better if it would operate with 48 volt supplies for ex-telecom
> equipment.
There are tons of chips in that
Bob kb8tq writes:
> Two basic types of SLA / VRLA batteries out there: AGM and Gel. For the AGM
> variety, you want a bit more to your charger.
Yes, if you buy batteries for N * 100K $money, spending more money
on your charger is a good investment.
But if you have two batteries doing
Hi
Two basic types of SLA / VRLA batteries out there: AGM and Gel. For the AGM
variety, you want a bit more to your charger. I haven’t worked with Gel cells
in
a while so they may indeed be easier.
Bob
> On Sep 25, 2020, at 4:17 PM, Poul-Henning Kamp wrote:
>
>
> Bob kb8tq writes:
Bob kb8tq writes:
>Properly charging batteries is a bit complicated.
With VRLA lead-acids: Not really, constant voltage 2.3V/cell, current limited
to $Ah/10 and you're done.
For the tonnage of batteries relevant for us, when used indoors,
temperature-compensation and all that is not
Yes, Powerpole connectors are wonderful; I use them extensively and in
various color combinations for different voltages.
Yes, it would be nice to have a Powerpole option for the Mini-Box
Y-PWR-Hot-Swap-Load-Sharing-Controller identified below, but it would be
even better if it would operate
Mark Spencer writes:
> The bit I am struggling with re using a 24 volt battery system in this
> application is what happens when AC power is removed and the terminal
> voltage of the battery starts to fall.
Don't overengineer your supply (unless you absolutely want to :-)
It looks
I've had good luck with Iota brand chargers for 12 and 24 volt... I
think they are "DCL" series or something similar. They are available in
various amperage and include a smart-charger circuit. I know Amazon
sells several models and the prices are in the $100-200 range. One of
their selling
Hi
Properly charging batteries is a bit complicated. Why does “properly” matter?
You want them to be fully
charged, but not damage them in the process. That generally involves some sort
of variable voltage
for the charging source. If you decide to go with Lithium based parts, you can
get BMS
Hi
If you run a straight linear regulator setup, then you *do* indeed have a
battery voltage
that is (nominally) much higher than the “target” voltage. If you run a diode
voting input,
then the “normal” voltage will be even higher. You can easily get into the 35
to 40V range
doing this.
Bob
Thanks Paul.
The bit I am struggling with re using a 24 volt battery system in this
application is what happens when AC power is removed and the terminal voltage
of the battery starts to fall.
Between voltage drop in the regulator, the voltage drop in any extra diodes
etc, a nominal 24 volt
Mark Spencer writes:
> I like the idea of using a diode arrangement to facilitate changing the power
> source for the BVA. I expect I will also add some form of over voltage
> protection as well.
If you are after the low noise, be weary of "integrated" lithium batteries of
12V and
Note that many (maybe all) TCXOs exhibit a hysteresis effect when the
temperature cycles. The stability reported on the datasheets is only
tested with a temperature change in one direction. Cycling temperature
up and down will result in more variation. I've seen two or three
times the datasheet
Pondering the backup power issues for my BVA a bit more, I am thinking a
dedicated DC battery bank (maybe 5 or 6 nominal 6 volt batteries in series)
powering a suitable linear regulator circuit is probably the direction I will
go in. I suspect there are more elegant and or simpler approaches
Hi,
On 2020-09-24 23:47, Tom Van Baak wrote:
> > Next time I power down mine is to integrate a new supply and back-up
>
> May I recommend PowerPole connectors and frequent use of diode-OR. For
> details see:
>
> http://leapsecond.com/pages/powerpole/diode-or.htm
>
> I got the inspiration when my
Hi
> On Sep 25, 2020, at 5:44 AM, Hal Murray wrote:
>
>
>> 1) In an unconditioned/semi-conditioned space. The ambient temperature can
>> slew 20*C easily over the holdover period. (Think sun hitting an outdoor
>> enclosure first thing in the morning - the ambient temperature tends to rise
Hi
How often do you loose power? If it’s once a year for < 1 hour …. how big an
issue is this to you? Do you *need* to do precision measurements every day?
Is restarting a run once a year a major issue? Option one is to simply restart
after an outage. Option two is to protect against it.
To
Bill, most modern double-oven OCXO's (including I think the BVA under
discussion) are under 5W average consumption after warmed up.
Most UPS's are rated for near-peak-power output (most of a kW or more) for
5 or 10 minutes to give time to shut computers down gracefully and are not
sized well for
Some of these sites already have a internet-connected temperature sensor on
a PCB inside a unvented plastic (electronics) enclosure inside the outdoor
weatherpoof metal enclosure. With just a quick look, I found one which
slewed from 21C to 65C over 2 hours within the last couple weeks. I don't
Tom Van Baak writes:
> May I recommend PowerPole connectors and frequent use of diode-OR. For
> details see:
+1 on the power-polery.
I really wish somebody would do a version of this with power-pole:
https://www.mini-box.com/Y-PWR-Hot-Swap-Load-Sharing-Controller
--
There is a command line option (and maybe a direct keyboard command) for
setting the plot queue size. Sorry, I'm away from a Heather machine and don't
remember what it is. You could also write a log file or receiver raw data
stream capture file and extract the data from that.
Re. OP mentioning battery back up.
Just a thought but a lot of places who maintain UPS units have a lot of surplus
batteries that are often in
reasonable shape.
If you're careful and bring a multimeter its possible to snag a good unit which
has lost capacity but otherwise
works and techniques
> 1) In an unconditioned/semi-conditioned space. The ambient temperature can
> slew 20*C easily over the holdover period. (Think sun hitting an outdoor
> enclosure first thing in the morning - the ambient temperature tends to rise
> quickly).
It would be interesting to get some data on
I accidentally only replied to an off-list reply with the following
information. It was also meant to go to the entire list:
Let me clarify here a bit:
The application is:
1) In an unconditioned/semi-conditioned space. The ambient
temperature can slew 20*C easily over the holdover period.
I plan to keep BVA powered. My question was how do you accomplish this and
what do you do it with? I've been using PS like for example Fluke
PM2811, Tekpower TP3005T, Dr. Meter HY3005F-3 (these are similar), Sorensen
and some older HP. I've had good luck them all so far. I'm curious if
I found http://www.leapsecond.com/pages/adev/ being pretty helpful to
get the concept.
Best, Ulli
Am 24.09.2020 um 21:35 schrieb Tom Van Baak:
Hi Hal,
ADEV turns out to be pretty hard to understand. I took me years for it
to sink in. There are web pages, articles, even books. Part of the
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