Don, I have the same transducer as you do, the 40 kHz Langevin
Now that I am done with the trailer, etc, I can start looking into
making an ultrasonic cleaner from this transducer. I would like to
hear if you have any suggestions for a simple oscillator that would
make this transducer work properly. I would prefer simple to design
Also, what kind of stainless tank would you suggest for it.
There are some schematics on Branson's website. See, e.g.,
I have a hunch (but don't know for a fact) that L1 and/or T2 in the
referenced schematic may be square-loop inductors. I have some small
squareloop toroids if you want a couple. You'd need to strip them and
wind them with what is needed. The MOSFET's cited are obsolete, no
problem. Pick any 400-volt several-amp TO-220 MOSFET, there are
many good choices at Digi-Key for a buck or two, or I could send you a
coupla those as well.
I don't have any ideas for SS tanks other than see what you can
scrounge as surplus medical or thin kitchenware. I don't think
there's anything critical other than thin is good. Ya might find a
good thin SS tank in a discarded deep fryer.
I found the "magic epoxy" at a local distributor -- for 50 bux a tube.
I've somehow managed to contain my enthusiasm for grabbing a tube.
A single 70W 'ducer probably won't have a lot more moxie than the $49
HF unit. Larger cleaners use several 'ducers.
I haven't played with my xdcr yet other than just fooling at the elex
bench. May not get around to that for a while. Truth be told, the HF
unit is working fine for me. I wanted the 'ducer for other
experiments, as perhaps coupling ultrasound directly into a
liquid-filled fouled firearm barrel with some sort of matching horn.
Don, how big of a tank can I use with this transducer. (not sure how
big is your HF tank)
Also, I have a fundamental question. What if I simply build a variable
frequency, variable power oscillator circuit with a big amplifier. I
could even attach an amplifier to a wavetek that I have. Then I could
carefully select proper resonant frequency that matches this
Which I think is easy with some ICs, a little trim pot and a
darlington of one sort or another.
Would that not be enough to make this transducer make ultrasound
What am I missing here?
I looked at that schematic. Did not really understand what it does,
specifically why there is a second transformer with two primaries.
On Thu, 01 Mar 2007 09:01:57 -0600, Ignoramus23363
Don, I found something interesting that explains why there is a second
Chapter 14) Ultrasonic cleaner schematic
Ultrasonic cleaning is a means of removing dirt and surface contamination from
intricate and/or delicate parts using powerful high frequency sound waves in
a liquid (water/detergent/solvent) bath.
An ultrasonic cleaner contains a power oscillator driving a large piezoelectric
transducer under the cleaning tank. Depending on capacity, these can be quite
A typical circuit is shown below. This is from a Branson Model 41-4000 which
is typical of a small consumer grade unit.
1, 1/2 W EDA456 |
C1 D2 |
| .1 uF | EDA456 | 2
| 200 V | +-----+---+ T1 +---+------->>------+
| R2 | _|_ C2 )|| o 4 | | |
+---/\/\---+ --- .8 uF D )|| +----+ | |
| 22K _|_ 200 V )||( + |
| 1 W - 1 o )||( )|| _|_
+-----------------+---------+ ||( O )|| L1 _x_ PT1
| R3 | 7 ||( )|| |
| +---/\/\---+ +-----+ ||( 5 + |
C \| | 10K, 1 W | F )|| +---+ | |
Q1 |--+-+--------------+ 6 o )|| | | |
E /| | D3 R4 +---+ +----+------->>------+
| +--|<|---/\/\--+ _|_
| 47, 1 W | --- Input: 115 VAC, 50/60 Hz
| | | Output: 460 VAC, pulsed 80 KHz
The power transistor (Q1) and its associated components form an self excited
driver for the piezo-transducer (PT1). I do not have specs on Q1 but based on
the circuit, it probably has a Vceo rating of at least 500 V and power rating
of at least 50 W.
Two windings on the transformer (T1, which is wound on a toroidal ferrite
core) provide drive (D) and feedback (F) respectively. L1 along with the
inherent capacitance of PT1 tunes the output circuit for maximum amplitude.
The output of this (and similar units) are bursts of high frequency (10s to
100s of KHz) acoustic waves at a 60 Hz repetition rate. The characteristic
sound these ultrasonic cleaners make during operation is due to the effects
of the bursts occuring at 60 Hz since you cannot actually hear the ultrasonic
frequencies they use.
The frequency of the ultrasound is approximately 80 KHz for this unit with a
maximum amplitude of about 460 VAC RMS (1,300 V p-p) for a 115 VAC input.
WARNING: Do not run the device with an empty tank since it expects to have
a proper load. Do not touch the bottom of the tank and avoid putting your
paws into the cleaning solution while the power is on. I don't know what,
if any, long term effects there may be but it isn't worth taking chances.
The effects definitely feel strange.
Where the device doesn't oscillate (it appears as dead as a door-nail), first
check for obvious failures such as bad connections and cracked, scorched, or
To get inside probably requires removing the bottom cover (after pulling the
plug and disposing of the cleaning solution!).
CAUTION: Confirm that all large capacitors are discharged before touching
The semiconductors (Q1, D1, D2, D3) can be tested for shorts with a multimeter
(see the document: "Basic Testing of Semiconductor Devices".
The transformer (T1) or inductor (L1) could have internal short circuits
preventing proper operation and/or blowing other parts due to excessive load
but this isn't kind of failure likely as you might think. However, where all
the other parts test good but the cleaning action appears weak without any
overheating, a L1 could be defective (open or other bad connections) detuning
the output circuit.
On Thu, 01 Mar 2007 09:13:43 -0600, Ignoramus23363
There ya go! Steminc has confirmed that these transducers can take
up to 2KV if properly matched to the load. They suggested using a bit
more liquid than "normal".
If/when I get motivated to work with my 'ducer I'll post my
wanderings and flagellations. At the moment, however, this project
is not on my priority list. It does appear to be on yours, so lead
On Thu, 01 Mar 2007 09:01:57 -0600, Ignoramus23363
The HF tank is about 6-5/8 x 5-3/8 x 2-5/8 deep.
That'd work, but tuning would be fussy. The Q of these xdcrs is about
1000, so the 3dB bandwidth is about 40 Hz at around 40 KHz. It might
be tricky to adjust a Wavetek to that degree of precision and
stability. My Wavetek wanders about 20 Hz when set as close to
40,000.0 Hz as I can get it.
Possibly, if your oscillator is stable enough and at the right freq.
If you refer to TX2, that's a gate drive current xfmr with two
secondaries, driving the MOSFET half-bridge. Circulating current in
the resonant load will "pull" the oscillator into some semblence of
On Thu, 01 Mar 2007 12:46:24 -0600, Ignoramus23363
I don't know. There may be some minimum power density for cavitation,
but I don't know how much ultrasound disperses laterally in a liquid.
It probably is related to the ducer lateral dimensions in
wavelengths. Some fishing and depthfinder sonars (higher freq) have
fairly narrow cones.
Tank size may not make much difference if the ultrasound tends to be
mostly in a cone above the 'ducer -- though little or no cleaning
would occur in regions away from the cone. Larger cleaners have
Cleaners seem to have a recommended range of depths. That may have
something to do with standing waves in the vertical column of liquid.
I don't think that this will work, even if one is willing to ride the
controls, because the resonant frequency of the transducer will vary
with temperature, which will be rising because of the high power being
applied. Temp will eventually more or less stabilize, but it will never
be constant enough. This is why such transducer drivers use the
transducer itself to set the frequency.
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