Products > Test Equipment
-48VDC power supply to power Symmetricom device
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tverbeure:
I’m pretty sure that I just bought a Symmetricom OT-21 TimeSource that requires a -48V DC power supply… without having a -48V DC power supply.

So… where do I get such a thing? There’s surprisingly little info online other than expensive telecom grade new stuff.

Anyone who was able to solve this in a cheap way?
TimFox:
Acopian makes high-quality DC linear supplies.
Their link:  https://www.acopian.com/linear-regulated-power-supply-models.html
They are not cheap purchased new, but I have seen many of these DC supplies on eBay.
an example:  https://www.ebay.com/itm/266234574920?hash=item3dfcd13848:g:9rcAAOSwQNJkSD2S&amdata=enc%3AAQAIAAAA4Lao48wC6ANyPJM%2B%2Br3mgOXWFqfOGc9ivjq1oIk1x7r9qxAN32Y8c%2FGeyi3IIwRLnE2DdVp2ci%2Fynf3NynPyWIdkavWRZugB5qrTEB6697eWbw0X5BExabQ6JKVJ4%2BeDRF66kfGbbArlIkccL1AdcOFzpqmFseMU7UTr%2FXkPbUelNd1MTEbyGlbZ7M%2FzayMXlmNHwcYXbrKM16QPyFQRc1TUbYMzarVrL8klgNMLm0MVekyEUlq%2FBJ2TZKtzudIO%2B76E78ToYqlHlAHJhKdD8V58tkIoPI9nEYtkI5bvCIod%7Ctkp%3ABk9SR_iPh6SrYg

Note that many eBay sellers of Acopian don't understand what they have and post the ratings by what they read by the fuseholder, e.g. 1/2A 250 V.
That makes eBay's sort by output voltage useless for these units.
Generally, the DC output voltage is two digits following the initial letter.
24 V is far more popular than 48 V, but you might get a deal on a dual 24 V supply.
iJoseph2:

--- Quote from: tverbeure on July 15, 2023, 02:20:21 pm ---Anyone who was able to solve this in a cheap way?
--- End quote ---

I thought PoE edge switches were -48v, but ..

https://www.ebay.co.uk/itm/265994633767

.. that Juniper one's -54v.

I think the Extreme edge switches have DC-DC within the switch chassis so their power supplies are only +12v ..
https://www.ebay.co.uk/itm/364085635781

Is +48v 1amp any use? ..
https://www.ebay.co.uk/itm/364088948243

tverbeure:
Thanks, that’s very useful!

I assume that I could use an +48V or +-24V supply, as long as they have a floating ground?

I have an E3631A power supply with +25/-25V and floating ground.
wasedadoc:
On ebay I see a photo of the rear with the two power input terminals labelled '-48VDC' and 'RTN'. Also '1 Amp'.
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