[time-nuts] time-nuts Digest, Vol 190, Issue 5

[Bob kb8tq]

Hi

Indeed, for anything designed as a mobile device, you want the 15V supply rather than
the 12V. Set it to the low end of the range and you are fine. A lot of mobile gear is only
happy with > 13V on the input. If it pulls noticeable current, cable drop will get you on
a 12V supply. 

For a GPSDO or an OCXO, you do indeed want 12.0 V into the device. For the OCXO,
you might also want “point of use” regulation. Now you are right back to a 12 + 2 = 14V
supply. 

Bob

> On May 3, 2020, at 12:52 PM, Dave B via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Has anyone found schematics for the Mean Well supplies? I have a couple of 15V 7A ones that will adjust down to 14.1 and I?d like to get them down to the 12-13.8 range. 
> 
> Steve
> WB0DBS
> 
> 
> If they have remote sensing, you can do stuff with that too.  Else, trace out the cct around the voltage setting pot, there will probably be some fixed resistor at each end, one or other will move the high or low point as you need.  (Lower values = greater adjustment range.)
> 
> BUT!  Note, that though you can usually lower the output voltage, you will not get any extra current as that is limited by the transformer design and capabilities.
> 
> Similarly, if you raise the output voltage, you will need to de-rate it's current output ability, so as not to exceed it's power capability.   Don't go too far from nominal (especially lower voltage) as the control loop regulation may misbehave under some load conditions. 
> 
> In any case, 14.1 is OK for most "12V" kit, especially anything that is intended for use in a vehicle, where the engine running battery voltage can often be up near 15V with modern vehicles and battery chemistry.
> 
> 73.
> 
> Dave G0WBX.
> 
> 
> On 03/05/2020 17:00, time-nuts-request at lists.febo.com wrote:
>> Has anyone found schematics for the Mean Well supplies? I have a couple of 15V 7A ones that will adjust down to 14.1 and I?d like to get them down to the 12-13.8 range. 
>> 
>> Steve
>> WB0DBS
> 
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