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New miniature programmable DC power supply - FNIRSI DPS-150

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Aldo22:

--- Quote from: ptluis on September 25, 2024, 03:12:40 pm ---For low noise I always use battery as source and in cases were sensors with output up to 100mV always use battery as source without using smps or dc-dc converters only analog.

For lower voltage DUT you should always choose a ps that allow you to source it from battery pack , that's why I'm converting all my equipment to portable including Scopes, sig gen, etc, etc

You save alot of headache's

--- End quote ---

A battery is certainly very good, but last week I made a power supply from an old Christmas tree transformer 12VA AC, 4 x 1N5399, a few capacitors and an L7812CV (without knowing what I was doing) and it is almost as "low-noise" as a battery.
I was amazed.  ;D

I could actually use this as an input for the Fnirsi.

ptluis:

--- Quote from: Aldo22 on September 25, 2024, 05:21:14 pm ---
--- Quote from: ptluis on September 25, 2024, 03:12:40 pm ---For low noise I always use battery as source and in cases were sensors with output up to 100mV always use battery as source without using smps or dc-dc converters only analog.

For lower voltage DUT you should always choose a ps that allow you to source it from battery pack , that's why I'm converting all my equipment to portable including Scopes, sig gen, etc, etc

You save alot of headache's

--- End quote ---

A battery is certainly very good, but last week I made a power supply from an old Christmas tree transformer 12VA AC, 4 x 1N5399, a few capacitors and an L7812CV (without knowing what I was doing) and it is almost as "low-noise" as a battery.
I was amazed.  ;D

I could actually use this as an input for the Fnirsi.

--- End quote ---

That's a nice way to learn and build a PS, with a decent heatsink that 7812 is able to supply 1A without any problem, with low ripple. The spikes I see I bet they come from your scope PS

Aldo22:

--- Quote from: ptluis on September 25, 2024, 05:42:50 pm ---The spikes I see I bet they come from your scope PS

--- End quote ---

I don't know where they come from. They are "in the air".  ;)
I see a similar amount of noise even when I measure the battery pack.
In any case, this home-made PSU has almost no high-frequency noise.

EDIT: When I measure with the probes, I hardly see any spikes. The BNC cable shows much more noise.

Fungus:
What's shown here is noise, not ripple. Noise like that doesn't normally come from a switching supply, it's external.

ptluis:
The technique I use to measure PS ripple it's a kind of "special cable" that one side connects to the output of the power supply under test and on the other side (with the ground clip removed) I insert the probe on a soldered ground spring, the tip connects to a golden point on the pcb. 2 capacitors in parallel are added into the side where the probe connects. The two wires of this cable are twisted.

Aldo22 if you want to try this, beware with the capacitors operating voltage, the higher the better for safety reasons. You don't want to connect a 16V capacitor into a 60V PS  :palm:

Edit: Don't forget the polarity of the 47uF electrolytic capacitor! minus connects to the black wire!

This video shows how I do it:




This video also shows differences in different techniques, but I prefer the previous for it's flexibility to allow connecting different outputs connectors without much effort by using this "special cable"

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