Ultrasonic Drivers

The microblower made by Murata (Digi-Key P/N 490-5856-ND) requires a “driver” that apparently Murata does not make. Do you sell a driver for the 490-5856-ND microblower (and/or P/N 490-MZB3004T04-ND and/or P/N 490-MZB3005T06-ND)

Hi bkozak,

Welcome to the Tech Forum. We do not sell a specific driver for this blower, but I did find a schematic for a recommended driver circuit.

I had already found this sketch. Any suggestions for a manufacturer who could make a few of these boards?

We do offer a board manufacturing service at Digi-Key.
Click here for info on DKRed.
If you can design the board, you can have the empty boards made at DKRed.
You would just have to solder all the components onto it.

Hello, I think I can help you with this.

Good Afternoon Houari,

I forwarded your earlier email to the Precision Fermentation engineer who actually works on our boards. I will let you know what he wants to do. My role is to integrate the instruments, pumps, valves, etc. to get the desired result and to lead the development / testing / commercialization. However, I don’t get personally involved in board design.

Bill Kozak
Consultant
Precision Fermentation
248-835-5414

Hello,

I too was able to find the schematic that was posted earlier on this thread, and discovered that it was able to drive P/N MZB1001T02, as listed at the top of the schematic. I was able to purchase an “eval kit” from here.

Unfortunately, the same circuit does not appear to drive P/N MZB3004T04. On looking at the datasheet, the resonant frequency of the MZB1001 is 24.0 to 27.0kHz. The resonant frequency for the MZB3004 is listed as 21.5 to 24.5 kHz. My guess is that the driver board is oscillating at a higher frequency than the MZB3004 will resonate at. Maybe the frequency can be changed by swapping out some of the components?

There is a different schematic on the datasheet for the MZB3004:

if the image isn't great, the datasheet can be downloaded from DigiKey's site. The schematic is on pg. 14. Fair warning - it's not much clearer.

I’m having a hard time reading/deciphering the labels, particularly at the top left corner of the screen, on Q1. The way I read it, the voltage source (I think) at the top left is Vs, and the other voltage, at the bottom right, is Vc.

The only way I can make sense of this is that the Vs is where the DC 8-18V is applied, and the Vc is routed to the rest of the schematic, but I can’t be sure because the schematic is so fuzzy.

I recreated the schematic as best I could using Altium. Here’s a PDF of the schematic I created.

MZB3004T04 Driver.pdf (56.9 KB)

Has anyone built this schematic or successfully used the MZB3004T04 microblower? If so, can you please explain/clarify the schematic?

Thanks

Agreed. My guess is it’s meant as a soft-start network of some kind. At a glance, it would appear that amps A & B are basically pre-drivers for the BJTs, amp C looks like some sort of current monitor/feedback/level control, and the network around amp B is responsible for the phase shift necessary to produce oscillation. I’d suggest dropping it into LTspice or other simulator of choice for closer study.

Hi all,

I think Rick’s explanation is accurate. Actually, amp B is a high-Q band-pass filter, which is a bit strange choice, as then the circuit is much less fail-safe. E.g. If the center frequency of the filter is too much off, or the supply voltage is too low, then the circuit won’t oscillate and that may damage the microblower.

Cheers,
heke, AsamaLab

Update:

I created a board layout based on the schematic I created in Altium, the schematic I created and posted earlier. I received the boards last week (DKRed - not a great experience either - mostly lack of communication) and was able to build one up today. I’ve tested the circuit 2 different ways, by applying power to Vin and GND at 10VDC, with a 100mA current limit. This clamped the supply to ~7VDC with no signs of life from the microblower. Applying power to Vs and GND had a similar result, clamping the supply to ~0.7VDC.

I’ve had no success with trying to contact Murata support directly, and the support available through DigiKey global tech support has been very limited, and altogether not useful.

Anyone have any additional insight on how to make this schematic work? Alternatively, is there a way to alter the schematic for the MZB1001 to change its operating frequency to match the MZB3004?

Did you mean Vc? What’s labeled Vin in your schematic is a mid-supply reference, and powering the apparatus at that node wouldn’t be expected to give favorable results.

When the current limiter clamps to one diode drop when trying to power a new circuit, I usually take that as an indication that something’s backwards, that I made an error in layout, or that I planted the wrong part. Take a careful look for silly mistakes and give it another go…

The peak-peak drive applied by the circuit in question appears to be double that developed by the first in the thread, which may have some bearing on things.

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Thanks for the suggestion. After writing my last post, I checked things over, and noticed that there was an error in the copper. The schematic was laid out correctly, but the pin mapping was wrong on one of the components. (I suppose that’s what you get for having a mechanical engineer do the PCB design/layout :face_with_diagonal_mouth:) I was able to flip the component upside down to make it work this time, and I’ll fix the layout for the next run of boards.

Anyway, with that fixed, I have a functional driver board for the MZB3004 microblower. We are feeding 8-18VDC to Vs and GND, and the blower draws 30-60mA in operation.

The next thing I’ve come up against is the need for more airflow, which brings to mind another question (again, mechanical engineer here…). Is this circuit intended to be adaptive - so that it finds the resonant frequency of the particular microblower that it’s connected to, or does the circuit operate at a fixed frequency? Because of the low current draw of a single microblower, I am hoping to be able to drive 2 blowers in parallel to get increased volume flow. Obviously, if each microblower has its own, slightly-different resonant frequency, and the drive electronics “finds home” at the resonant frequency of that particular microblower, this may not be possible. But, if the circuit has a fixed frequency and the microblowers can/will resonate at any frequency in the range stated on the datasheet (21.5 to 24.5 kHz), it seems like I could drive 2 blowers on a single circuit.

Are there any holes in this logic?

The blowers themselves appear to function as part of the the oscillatory mechanism in both instances, so a person’s probably looking at some sort of self-tuning circuit there.

I don’t have much information as to typical spreads of component characteristics, or the influence of operating somewhat off-resonance as a consequence of averaging device characteristics. A person could probably get some useful information empirically, but from a product planning standpoint I wouldn’t bet the farm on being able to happily run more than one on a given drive circuit.

That’s what I figured. Turns out we’ll be able to make a single blower work, so it’s a non-issue anyway.

Thanks for all the help!