Regulator test rig you don't need to suck.

[northernone]

Do these components look right?

Without the satisfaction of wiring up a custom pwm of course.

Cameron

 

[njmorrell]

Those all look OK to me. I looked at the pump on eBay, the spec. is -30KPa which is more than enough, 30KPa is about 120in WG! It doesn't say what the volume capacity is but for $3.98 it's worth a try. The capacity of the pump I used is 6 lpm, again more than enough.

Post a photo of your finished unit.

Rgds Nick.

 

[rsingler]

Here's mine. This thing is amazing!

My schematic is this:

And my parts are these:
From Home Depot:

From eBay:

That comes to only $20 each if you can get three of you building them at once.
And you could save quite a bit if you bought the pump and circuit board direct from China, but the U.S. distributor gets them there faster. And you may have an old toy power supply lying around.

The precision of the measurement as you watch for a drop on your IP gauge is incredible.
Interestingly, you don't really even need your IP gauge after awhile. The volume capability of the pump is actually quite small, though the suction it can apply is large. Therefore, what happens is that once the second stage valve opens, the little pump can generate only about 0.1" more on the magnehelic, no matter how high you run the rpm.
So with practice, just run the motor up and see where it peaks. Subtract 0.1" and that's your cracking effort. It makes it very quick for second stage adjustment, and as noted before, SO precise!

I use the adjustable air bleed of the garden irrigation bubbler to put the rpms of the motor at a reasonable midpoint. If there's not a substantial air bleed into the circuit, the motor rpms have to be so low (when you're only generating 1"WC of suck) that the magnehelic needle jerks a little. The air bleed really smooths things out. You'll need to tighten it down a little when you're tuning a downstream octo when you're trying for 1.6" or higher.

 

[Open Ocean Diver]

I have the same set up except I have a flowmeter in series with the mouthpiece, I run the pump full out and adjust the suction with a multi-turn needle valve.

 

[Open Ocean Diver]

Edit: removed the flowmeter (reluctantly) after speaking with Rob it was causing errors in my readings.

 

[BigRed96]

Here’s mine. I was using it wrong at first thinking it would completely open the supply valve. After I figured it out that it only barely cracks the regulator assembly open it was good to go.

 

[-JD-]

Since we are showing our variations, I made one to fit in my Gauge Box (shown here: DIY regulator test/flow panel).

Please forgive some blurry photos - I was trying to finish it up and grabbed my cell phone to get pics as i was building it. Add difficult lighting ...


I got it to fit in an inexpensive Raspberry Pi case.

Parts and construction ...

Vac/Motor (DC 5V 6V 370 Mini Motor Air Pump Vacuum Pump Self-Priming Monitor Breast Pump US | eBay)

USB PWM board (NOYITO 5V USB Fan Stepless Speed Controller Regulator with Switch Speed Modul... | eBay) used as a motor speed controller. I removed the USB-A Input port and swapped out the 4-pin USB-A output port for a 3-pin JST connector matching the motor (I had to jumper 2 adjacent pads to get the power over to the negative pin position on the JST.) This board also has a Micro-USB input which I am using.

Micro-USB extension/panel mount (https://smile.amazon.com/gp/product/B06Y1M38S3) Second Picture shows the trimmed-back strain relief needed to fit things:

3/16" Barb-barb bulkhead fitting (https://smile.amazon.com/gp/product/B07HF3RF1X):

Pi-Case (https://smile.amazon.com/gp/product/B07PNB7JWP)
Drilled holes for air bulkhead fitting and Micro-USB panel mount:

Some more holes to mount the PWM-Board potentiometer:

Some mounting holes on the bottom to accept sheet-metal screws:

And enlarge a hole on the back for a locating stud and drill down a couple of the standoffs:

Now, to put it all together ...

Put in the locating screw and the air and power connections. Vac/Motor just squeezes in there nicely.

Connect the motor to the the PWM board and install it. Then hook up the air line to the vac pump:

Wind the Micro-USB extension cable and plug it into the PWM board input:

Give it a test, slap the cover on, and go have a beverage ...

 

[Open Ocean Diver]

I find if you install a needle valve in front of the pump and run the pump RPMs to base speed and use the needle valve to control the suction volume instead of motor speed you get rid of the annoying needle bounce on the magnehelic gauge. You can also use the same setup to do a water leak test. I use a vent between valve and pump so I can lockdown the vacuum when the valve is closed.

 

[Open Ocean Diver]

I find if you install a needle valve in front of the pump and run the pump RPMs to base speed and use the needle valve to control the suction volume instead of motor speed you get rid of the annoying needle bounce on the magnehelic gauge. You can also use the same setup to do a water leak test. I use a vent between valve and pump so I can lockdown the vacuum when the valve is closed.

 

[-JD-]

@Open Ocean Diver thanks for the schematic.
@rsingler uses just an adjustable vent with the PWM speed control.

I tried an aquarium airline valve as a vent, but wasn't seeing much difference. Possibly just a poor valve and/or my lack of understanding what to look for. It is easy enough to experiment with the valves externally to see what works. Getting something precice and small enough to fit may be difficult.

I had also thought of a venting valve to load the output side which may be adventagous for packaging.