Ultrasonic Range Meter

R

roots_of_culture

Jan 1, 1970
0
Hi,
I am trying to build an ultrasonic range meter using an AU5550
(http://www.jaycar.co.nz/products_uploaded/AU5550.pdf) - 40 khz
transducer. i am using the pic16f877a to send the 40 khz pulse to the
transducer, 12v supply.

-- I realise that i need to use P/N channel hexfet power mosfet totem
pole, but i am stuck at which driver to use and how.

-- Other Driver Ideas....Circuits...
Any and all sorts of help appreciated.
 
S

Stef Mientki

Jan 1, 1970
0
roots_of_culture said:
Hi,
I am trying to build an ultrasonic range meter using an AU5550
(http://www.jaycar.co.nz/products_uploaded/AU5550.pdf) - 40 khz
transducer. i am using the pic16f877a to send the 40 khz pulse to the
transducer, 12v supply.

-- I realise that i need to use P/N channel hexfet power mosfet totem
pole, but i am stuck at which driver to use and how.

-- Other Driver Ideas....Circuits...
Any and all sorts of help appreciated.
Click to expand...
Why 12V supply ?
In my opinion 5V is enough,
take a look here
http://oase.uci.kun.nl/~mientki/pic/projects/rapid_prototyping/rapid_prototyping_us_ranger.html

Stef Mientki
 
R

roots_of_culture

Jan 1, 1970
0
Why 12V supply ?
In my opinion 5V is enough,
take a look here
http://oase.uci.kun.nl/~mientki/pic/projects/rapid_prototyping/rapid_...
Click to expand...

Im looking for a range of about 10cm- 6m, and i didnt think that a 5V
supply would be enough to drive the transducer hard enough to get the
range i desire.
And specifically 12 v supply, because i am using a 12 v car battery.

And i was also thinking that i will need a voltage regulator after the
12V battery, which will then leave me with a voltage of around 10.5 V.

i would like to use a driver circuit because the transducer is highly
capacitive and i didnt think i would be able to get sharp rise and
falls in the pulses i wish to transmit otherwise.
In the schematic below i have used schimdt trigger chip. But i want to
use a driver chip, something apart from the schimdt trigger.
(http://navdeep2u.googlepages.com/transmitting.JPG)
 
C

Chris

Jan 1, 1970
0
roots_of_culture said:
Im looking for a range of about 10cm- 6m, and i didnt think that a 5V
supply would be enough to drive the transducer hard enough to get the
range i desire.
And specifically 12 v supply, because i am using a 12 v car battery.

And i was also thinking that i will need a voltage regulator after the
12V battery, which will then leave me with a voltage of around 10.5 V.

i would like to use a driver circuit because the transducer is highly
capacitive and i didnt think i would be able to get sharp rise and
falls in the pulses i wish to transmit otherwise.
In the schematic below i have used schimdt trigger chip. But i want to
use a driver chip, something apart from the schimdt trigger.
(http://navdeep2u.googlepages.com/transmitting.JPG)
Click to expand...

Hi, Roots O' Culture. Your transducer can be seen as a capacitive
load. You're basically trying to do this (view in fixed font or M$
Notepad):

|
| .---------------.
| | |
| | | 5V-to-12V
| | | Level Translation/
| | | High-Current source/sink
| | | Buffer
| | | (Non-Inverting) |.--.| (Inverting)
| | | |\ || || /|
| | PIC o----o-----| >-----|| ||-----O< |---.
| | | | |/ || || \| |
| | | | |'--'| |
| | | | Transducer |
| | | | (1800pF) |
| | | '-------------------------------'
| | |
| | |
| | |
| '---------------'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Since you're already going with a PIC, Microchip has a pair of drivers
that will do exactly what you want -- the TC4420 (non-inverting) and
the TC4429 (inverting) high speed MOSFET drivers. They have the
capability to drive up to 6 amps with low Rds(on) MOSFETs built in, and
the IC takes care of the level translation for you. Put one on each
side of the transducer, and you're good to go. They're made to drive
capacitive loads, and have crossover protection built in. They'll
smack that T/R40-16B around real good (140 volts max!?! Is that an
aluminum, steel, or titanium case?).

Unless this is a high volume application, I don't think you're going to
be able to do better than this. The ICs are available in 8-pin DIPs,
too (CPA suffix).

Here's the datasheet:

http://ww1.microchip.com/downloads/en/devicedoc/21419c.pdf

If you want to be really safe, add a 2.2 ohm non-inductive resistor (a
1 watt carbon comp is good here) in series with the transducer to limit
maximum current doesn't exceed 6A.

|
| .---------------.
| | |
| | | 5V-to-12V
| | | Level Translation/
| | | High-Current
| | | Buffer
| | | (Non-Inverting) |.--.| (Inverting)
| | | |\ || || ___ /|
| | PIC o----o-----| >-----|| ||--|___|----O< |---.
| | | | |/ || || 2.2 ohm \| |
| | | | |'--'| |
| | | | Transducer |
| | | | (1800pF) |
| | | '-------------------------------------'
| | |
| | |
| | |
| '---------------'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

On the power supply end, the TC4420 and -29 are good to 18V, so you
shouldn't need another regulator. You also want to maximize voltage.
I'd recommend using another 2.2 ohm series resistor or choke and a
large (2200uF or greater, 25WV) cap with a Transzorb for a localized
charge source and to protect against load dump.

|
|Battery ___ To XDCR Power
|B+o----|___|--o---o->
| 2.2 ohm | |
| +| /-/
| 2200uF --- ^ P6KE16A
| 25WV --- |
| | |
| | |
| === ===
| GND GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Good luck
Chris
 
R

roots_of_culture

Jan 1, 1970
0
Chris,
Thanks, that has solved my transmitting circuit.

Andrew,
you are right TC4420 is not available at hand locally, but Farnell (
$4.40) delivers within 3 days, so that is good.
Though in order to get going im using the TC4428CPA, it has a low
Rds(on) 40 ns.

As for the recieving circuit, i saw a design from national in the
Electronic Design (jan 2006) journal. it uses a 2 stage LMP7711 (17MHz)
as active filters (band pass), with a gain of 100 * 10, but these are
not available locally either. I am trying to find substitutes.
 
M

Mebart

Jan 1, 1970
0
On 28 Mar 2006 01:38:52 -0800, "roots_of_culture
<[email protected]
wrote
Chris
Thanks, that has solved my transmitting circuit

Andrew
you are right TC4420 is not available at hand locally, but Farnell
$4.40) delivers within 3 days, so that is good
Though in order to get going im using the TC4428CPA, it has a lo
Rds(on) 40 ns

As for the recieving circuit, i saw a design from national in th
Electronic Design (jan 2006) journal. it uses a 2 stage LMP771 (17MHz
as active filters (band pass), with a gain of 100 * 10, but thes ar
not available locally either. I am trying to find substitutes
Click to expand...
My receiver is a POS affair without automatic gain so I've set th
transmitter PIC to be able to PWM at two different rates and as ye
the bandpass filter eludes me (rank novice). Need to do more researc
when I'm fresh. I'm using the Dual LM833N 8pin DIP (Min 10MHz, Ma
15MHz), high slew rate. I'll have a look at the LMP7711 too

Regards

Andrew
 
C

Chris

Jan 1, 1970
0
(Rubicon) said:
Chris,

Great diagrams and advice. I've been trying myself to create a simple
but "as long a range as I can get" ultrasonic remote control using the
same transducers and 16F628A PICs. The transmitter uses an AND gate to
switch a 100V N-mosfet with the transducer, 1000uH inductor and a
100ohm resistor. At 9.5V, 60% duty cycle sending two bytes over and
over at 300bps it does work up to approx 11 meters from the receiver.
I'm working again on a bandpass filter for the receiver and once I
figure that out I'll need help hopefully from the members of this
group to get an automatic gain cirucuit built. The last time I fiddled
with bandpass filters I cut the range down to two centimeters! Not
much of a remote then!

The initial link that roots_of_culture provided for the transducer PDF
is a Jaycar branch in New Zealand and assuming that he too lives here
then acquiring the drivers may be a problem for both of us.

For roots_of_culture - one company, South Island Components, is
trade/retail has only the TC4429CPA but doesn't stock the 4420 while
other retail outlets like Jaycar, Dick Smith and Altronics don't stock
them or any of the range at all. RS components deals with the trade
and requires a company account to be opened but they do have the:
TC4421CPA - 9A Single Inverting
TC4426CPA - 1.5A Dual Inverting
TC4427CPA - 1.5A Dual Non-inverting
TC4428CPA - 1.5A Combined Single Inverting and Non-invereting
TC4429CPA - 6A Single Inverting
(Note - RS sells the TC4429CPA for NZ$10.70 + GST eachwhile South
Island Components sells them for NZ$5.48 + GST)
Other than trying a few more companies I've found online in the Yellow
pages there's Farnell in Australia I suppose. Should my assumption be
correct and you do find a source for the TC4420 in NZ could you please
post it in this NG as I'd greatly appreciate that.

Regards

Andrew.
Click to expand...

HI, Andrew. The sun never sets on Farnell (I'm in the States -- it's
Newark here). Unfortunately, the Farnell website is being updated.
But looking at the Newark site, it seems they have the same issue.

You may want to try the TC4426 (dual inverting) and TC4427 (dual
non-inverting). You'll have to leave half of each chip dormant, unless
you have something else to do with them. To my recollection, you can't
parallel outputs safely.

The datasheets for the TC4426CPA (8-pin DIP, commercial temp range) and
TC4427CPA are available at the Microchip website:

http://ww1.microchip.com/downloads/en/devicedoc/21421d.pdf

The datasheet says they're rated for capacitive loads, and after all,
this isn't continuous use. You're only snapping the transducer a
couple dozen times, eight to twelve times a second. You really
shouldn't need a series resistor with the transducer unless you're
really cautious, especially considering the Rds(on) is typically 7 to 8
ohms. But by rounding the edges of the transition with the additional
Rds(on), you're losing some power.

http://ww1.microchip.com/downloads/en/devicedoc/21422d.pdf

Good luck
Chris
 
R

Rubicon

Jan 1, 1970
0
Hi, Roots O' Culture. Your transducer can be seen as a capacitive
load. You're basically trying to do this (view in fixed font or M$
Notepad):

|
| .---------------.
| | |
| | | 5V-to-12V
| | | Level Translation/
| | | High-Current source/sink
| | | Buffer
| | | (Non-Inverting) |.--.| (Inverting)
| | | |\ || || /|
| | PIC o----o-----| >-----|| ||-----O< |---.
| | | | |/ || || \| |
| | | | |'--'| |
| | | | Transducer |
| | | | (1800pF) |
| | | '-------------------------------'
| | |
| | |
| | |
| '---------------'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Since you're already going with a PIC, Microchip has a pair of drivers
that will do exactly what you want -- the TC4420 (non-inverting) and
the TC4429 (inverting) high speed MOSFET drivers. They have the
capability to drive up to 6 amps with low Rds(on) MOSFETs built in, and
the IC takes care of the level translation for you. Put one on each
side of the transducer, and you're good to go. They're made to drive
capacitive loads, and have crossover protection built in. They'll
smack that T/R40-16B around real good (140 volts max!?! Is that an
aluminum, steel, or titanium case?).

Unless this is a high volume application, I don't think you're going to
be able to do better than this. The ICs are available in 8-pin DIPs,
too (CPA suffix).

Here's the datasheet:

http://ww1.microchip.com/downloads/en/devicedoc/21419c.pdf

If you want to be really safe, add a 2.2 ohm non-inductive resistor (a
1 watt carbon comp is good here) in series with the transducer to limit
maximum current doesn't exceed 6A.

|
| .---------------.
| | |
| | | 5V-to-12V
| | | Level Translation/
| | | High-Current
| | | Buffer
| | | (Non-Inverting) |.--.| (Inverting)
| | | |\ || || ___ /|
| | PIC o----o-----| >-----|| ||--|___|----O< |---.
| | | | |/ || || 2.2 ohm \| |
| | | | |'--'| |
| | | | Transducer |
| | | | (1800pF) |
| | | '-------------------------------------'
| | |
| | |
| | |
| '---------------'
|
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

On the power supply end, the TC4420 and -29 are good to 18V, so you
shouldn't need another regulator. You also want to maximize voltage.
I'd recommend using another 2.2 ohm series resistor or choke and a
large (2200uF or greater, 25WV) cap with a Transzorb for a localized
charge source and to protect against load dump.

|
|Battery ___ To XDCR Power
|B+o----|___|--o---o->
| 2.2 ohm | |
| +| /-/
| 2200uF --- ^ P6KE16A
| 25WV --- |
| | |
| | |
| === ===
| GND GND
(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

Good luck
Chris
Click to expand...


Chris,

Great diagrams and advice. I've been trying myself to create a simple
but "as long a range as I can get" ultrasonic remote control using the
same transducers and 16F628A PICs. The transmitter uses an AND gate to
switch a 100V N-mosfet with the transducer, 1000uH inductor and a
100ohm resistor. At 9.5V, 60% duty cycle sending two bytes over and
over at 300bps it does work up to approx 11 meters from the receiver.
I'm working again on a bandpass filter for the receiver and once I
figure that out I'll need help hopefully from the members of this
group to get an automatic gain cirucuit built. The last time I fiddled
with bandpass filters I cut the range down to two centimeters! Not
much of a remote then!

The initial link that roots_of_culture provided for the transducer PDF
is a Jaycar branch in New Zealand and assuming that he too lives here
then acquiring the drivers may be a problem for both of us.

For roots_of_culture - one company, South Island Components, is
trade/retail has only the TC4429CPA but doesn't stock the 4420 while
other retail outlets like Jaycar, Dick Smith and Altronics don't stock
them or any of the range at all. RS components deals with the trade
and requires a company account to be opened but they do have the:
TC4421CPA - 9A Single Inverting
TC4426CPA - 1.5A Dual Inverting
TC4427CPA - 1.5A Dual Non-inverting
TC4428CPA - 1.5A Combined Single Inverting and Non-invereting
TC4429CPA - 6A Single Inverting
(Note - RS sells the TC4429CPA for NZ$10.70 + GST eachwhile South
Island Components sells them for NZ$5.48 + GST)
Other than trying a few more companies I've found online in the Yellow
pages there's Farnell in Australia I suppose. Should my assumption be
correct and you do find a source for the TC4420 in NZ could you please
post it in this NG as I'd greatly appreciate that.

Regards

Andrew.
 
R

Rubicon

Jan 1, 1970
0
Chris,
Thanks, that has solved my transmitting circuit.

Andrew,
you are right TC4420 is not available at hand locally, but Farnell (
$4.40) delivers within 3 days, so that is good.
Though in order to get going im using the TC4428CPA, it has a low
Rds(on) 40 ns.

As for the recieving circuit, i saw a design from national in the
Electronic Design (jan 2006) journal. it uses a 2 stage LMP7711 (17MHz)
as active filters (band pass), with a gain of 100 * 10, but these are
not available locally either. I am trying to find substitutes.
Click to expand...

My receiver is a POS affair without automatic gain so I've set the
transmitter PIC to be able to PWM at two different rates and as yet
the bandpass filter eludes me (rank novice). Need to do more research
when I'm fresh. I'm using the Dual LM833N 8pin DIP (Min 10MHz, Max
15MHz), high slew rate. I'll have a look at the LMP7711 too.

Regards,

Andrew.
 
R

Rubicon

Jan 1, 1970
0
On Wed, 29 Mar 2006 08:14:52 GMT, (Rubicon) wrote:

First off it was rude of me not to thank you in my last post for the
Farnell source confirmation - Thanks.

Secondly where did you get that Electronic Design Jan 2006 publication
from? I've looked on the net, found its publisher (Penton
Publications) and searched the CHCH city libraries to no avail. The
Electronic Design website is only a front page that constantly reloads
itself. The Europe one wasn't helpfull either.

Regards,

Andrew.
 
J

Jonathan Kirwan

Jan 1, 1970
0
<snip>
-- Other Driver Ideas....Circuits...
Any and all sorts of help appreciated.
Click to expand...

I only today noticed that Radio Shack is selling a completed
ultrasonic ranger as part of the VEX robotics stuff they sell.
Everything is "half off" until June, I'm told. The ranger is normally
$29.99 but is now selling for $14.99. It uses 5V supply and 3cm to
300cm ranging with 40kHz. Paperwork says it uses a 10us pulse; but
with a 25us single cycle width I doubt this spec. I might believe
100us, though, or 4 cycles. (Their minimum distance of 3cm
corresponds to a trip time of 175us.) Comes with screws for mounting
and a nice enough enclosure.

Just to let you know...

Jon
 
T

[email protected]

Jan 1, 1970
0
Hey Chris,
I'm doing a project on ultrasonic ranging too and the desired distance
is 50m. It seems rather far and I wonder if TC4420/4429 could help? And
can you explain how these things work cos I'm really confused about how
6A would help driving my transducer. :-/
Thanks
Martin
 
M

Martin

Jan 1, 1970
0
Hey Chris,
I'm doing a project on ultrasonic ranging too and the desired distance
is 50m. It seems rather far and I wonder if TC4420/4429 could help? And
can you explain how these things work cos I'm really confused about how
6A would help driving my transducer. :-/
Thanks
Martin
 
J

Jonathan Kirwan

Jan 1, 1970
0
I'm doing a project on ultrasonic ranging too and the desired distance
is 50m. It seems rather far and I wonder if TC4420/4429 could help? And
can you explain how these things work cos I'm really confused about how
6A would help driving my transducer. :-/
Click to expand...

Hi, Martin. I'm no expert on this stuff, but am generally interested.
But it seems to me that 50m really is a far distance. Two problems
pop into mind -- (1) energy spreads out (ignoring dissipation of
energy at 40kHz in air) at D^2 and returns with another D^2 factor, so
this suggests to me a D^4 hurdle to overcome and that would mean a lot
of initial energy (read as very high driving voltage) to get there;
and (2) reasonable resolution over that kind of range seems vaguely
problematic, too. I also don't know what the attenuation of the usual
40kHz is in (wet) air or if there are better or worse bands nearby you
might prefer. I wonder if there is a page documenting it over
frequency...

Have you found any existing ultrasonic ranger that works at 50m?

Jon
 
M

Martin

Jan 1, 1970
0
Hi Jon,
I think 50m is way too far too actually. There's this paper on
ultrasonic ceramic transducers on
www.senscomp.com/specs/piezo%20application%20note.pdf and it explains
all the losses and such.
For a 100V pp driver with a transducer's SPL of 108dB and the
receiver's sensitivity of -75db, according to my calculations, the
voltage at the receiver at 50m is about 0.2uV :)) With the help of a
cone I think this could get up a bit but still... Do you think I can do
anything with this?
 
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