Affordable Adjustable Lab Laser Diode Power Supply

[lasersbee]

We've been looking for an adjustable Lab Laser Diode Power
supply for quite some time now. We already have a commercial
Opto Power Corp OPC4005 40 Amp adjustable Laser Diode supply
that we use for Coating testing and LaserBee LPM calibrations.

That supply measures about 18" X 14" X 3.5" and weigh quite a
bit. We have looked at the eBay/AliExpress CV/CC power supplies
but don't like/trust their output noise/spikes.

Recently I've come across an EEVblog Y/T video of a small CV/CC
PS from an AliExpress seller and decided to get one of his other
PS models.
I decided on the DPH3205.

https://www.aliexpress.com/item/RD-...32762131242.html?spm=a2g0s.9042311.0.0.nTIpxS

This is a 32 Volt 5 Amp Constant Voltage/Constant Current PS
that has a small color LCD display with tactile control buttons
and a rotary selection control knob.

There is a Setup menu that you can set the Over Voltage
Protection as well as the Over Current Protection. That is
what I found very useful and is included in our much more
expensive OPC4005 PS.

I chose this model because the LCD display shows 1mA resolution
You also have an option to get the metal case designed for the
PS. I highly recommend buying it.

https://www.aliexpress.com/item/RD-...32794029335.html?spm=a2g0s.9042311.0.0.nTIpxS

The only thing I didn't like about it mechanically was that it did
not have a tilt handle to tilt the display up from flat on the work
bench. I designed a simple solution that anyone can easily build.

[See Attached Pic below]

Once it was assembled I decided to test the electrical specs
and check for hidden spikes while adjusting the Voltages and
currents on a Digital Storage scope. I attached a Dummy Load
to the output and scoped the Sense Resistor.

Depending on how clean the input supply to the PS is depends
a lot on the noise of the output. I typically get about 70mV to
100mV zero line noise.

Turning the supply output ON and Off from the On/Off button
on the Display panel showed no spikes at all or at least I didn't
detect any with a one shot scope detection.

Incrementing the current by 1mA steps showed a clean step
every time without and spiking.

Incrementing the current by 100mA steps again showed no
detectasble spiking on the scope.

To say the least... I'm very impressed with this extremely small
physical size of this CV/CC Power Supply and would recommend
it to anyone that wants an adjustable Lab style Laser Diode PS

And you can't beat the ridiculously low price for the quality
and specs....IMO

We ordered one of there new PS and are waiting on its arrival.
This model is similar to the one we tested but also includes
USB and/or Bluetooth connections to a computer with free
Win7 or later Software.


Jerry

 

[Encap]

Nice find ---modular features--many component options available as well -- several other configurations and combinations

Very reasonable prices---looks like these guy came up with good quality low cost products. that can be assembled to suit.
Is like a toy store for this kind of thing---they make a lot of different items and all of them look good.

They make a large array of interesting and affordable items with modern features.

This USB and bluetooth module with software looks good--they make a nice housing for it as well https://www.aliexpress.com/store/product/RD-DP-and-DPS-Power-Supply-communiaction-housing-Constant-Voltage-current-casing-digital-control-buck-converter/923042_1000004752402.html?spm=2114.10010108.1000023.17.323cb8d24RvGAa

 

[paul1598419]

This seems to have the same circuitry as cheaper power supplies with all the same features they have, except the enclosure and a few other odds and ends. Instead of scoping the current sense resistor on the dummy load, I'd scope across the output of the CV/CC circuit. Might be more noise there than at the end of the line at the resistor. If it works for your purposes, that's all that matters.

 

[lasersbee]

This seems to have the same circuitry as cheaper power supplies with all the same features they have, except the enclosure and a few other odds and ends. Instead of scoping the current sense resistor on the dummy load, I'd scope across the output of the CV/CC circuit. Might be more noise there than at the end of the line at the resistor. If it works for your purposes, that's all that matters.

Which cheaper power supplies are you referring to Paul..:thinking:

BTW I did the test you suggested without the Dummy
Test Load and directly on the CV/CC output and the
noise level was the same. The Turn On/Off spiking was
also not noticeable as the 1st test.

The knob current adjustment spiking was still not noticeable
on the scope. I did need to load the output to be able to
increase the output current while checking the CV/CC output
voltage on the output terminals.

Jerry

 

[paul1598419]

Hi, Jerry. I don't have a link at the moment, but they are CC/CV power supplies that are rated at 30 VDC and 5 amps for ~$45.00 from China. Sounds like your supply is reasonably noise free. That is especially important when adjusting it. I'm glad it worked out well for you, but you never know until you test it.

 

[lasersbee]

It's not my supply... I didn't design it..:yh:

I just thought I'd share what I recently
boght/built/Tested and used for testing
some shop LDs up to 5 Amp currents that
I found incredibly inexpensive for the quality
and specs.

I've since bought 2 more different models
One at 50V and 15 Amps. Hopefully it also
is Spike Free and low noise.

Jerry

 

[paul1598419]

Semantics. I didn't mean your supply in that you built it. It is yours because you bought it. :crackup:

 

[waffailtrager101]

Thank you for posting this. As you can see, I'm fairly new to all this, which means I don't have a lot of the gadgets. Knowing that there is a cheaper option that won't cause voltage spikes is awesome.

 

[Cyparagon]

A notable omission: These require an input voltage source, and are buck converters. You only get full voltage/current range if you have an external PSU at 36V+ input capable of 5A+. That will double or triple the price if it isn't something you already have lying around.

 

[diachi]

Dave at EEVBlog covered a similar unit in a couple of videos.

A notable omission: These require an input voltage source, and are buck converters. You only get full voltage/current range if you have an external PSU at 36V+ input capable of 5A+. That will double or triple the price if it isn't something you already have lying around.

Yup, not quite just plug and play. If you don't need the full range you could get away with using the 12V rail from an ATX supply, although that sort of defeats the point of buying a model that has this range.

 

[lazeristasUVISIR]

Yup, not quite just plug and play. If you don't need the full range you could get away with using the 12V rail from an ATX supply, although that sort of defeats the point of buying a model that has this range.

I assume there will be some smoke if you connect a LD directly to ATX. (or you mean something different in underline text?)

 

[diachi]

I assume there will be some smoke if you connect a LD directly to ATX. (or you mean something different in underline text?)

Read the post I quoted, then read my post.

 

[lazeristasUVISIR]

Read the post I quoted, then read my post.

I assume then anything after "although" could be omitted.

 

[diachi]

I assume then anything after "although" could be omitted.

Well... No? What's the point of buying a 0-32V supply if you're only going to get what, 0-8V out?

 

[lazeristasUVISIR]

Well... No? What's the point of buying a 0-32V supply if you're only going to get what, 0-8V out?

I think this one has advantage of the current limit, and voltage would adjust accordingly (current supply; CC). Not like with PSU 12V output to fry diodes (voltage supply; CV)

 

[diachi]

I think this one has advantage of the current limit, and voltage would adjust accordingly (current supply; CC). Not like with PSU 12V output to fry diodes (voltage supply; CV)

We're not talking about hooking up a 12V supply direct to diodes though...

This power supply needs an external DC power supply. It's a buck supply, therefore the maximum output voltage must be lower than the input voltage.

I suggested that if someone doesn't have a 36V supply around to power this variable supply, they could just hook up an old ATX supply to power it.

However, doing so would defeat the point of getting the 0-32V model as you'd only get around 0-8V.

I'm making sense here, right? :thinking: