Hi David,
I guess you know the 150kHz transducer will work in 'air', reflected off say a wall or metal screen.
Of course the air velocity will be around 330m/sec as opposed to a typical 1480m/sec in seawater.
The signal strength will be lower due to the poor air impedance match, but enough to carry out bench testing.
E

 

Below is the LTspice simulation of a gated burst using two 555 (or one 556) timer(s), but I couldn't avoid an external transistor.
By adding an emitter follower buffer (Q1) to rapidly charge C2, the circuit was able to generate the short 0.1ms output pulse (as determined by R2) with a 1s period (as determined by R1).
The U2 astable generates the 150kHz signal.
R5 allows adjusting the duty-cycle to give an approximate 50% duty-cycle output.

As you can see, the 150kHz burst from U2 is 16 cycles long.

View attachment 258787

Hi David,
I guess you know the 150kHz transducer will work in 'air', reflected off say a wall or metal screen.
Of course the air velocity will be around 330m/sec as opposed to a typical 1480m/sec in seawater.
The signal strength will be lower due to the poor air impedance match, but enough to carry out bench testing.
E

Thanks Eric, yes Thought about bench testing in air.
Instead of shelling out £40 for new second transducer for the receiver for testing, could I use a cheap Piezoelectric microphone(I don't know if a audio one could work at 150khz probably not)

or buy a cheap leaded piezo wafer set for 150khz(I think I've seen some like this advertised somewhere)

thanks again david

 

Hi David.
This is a LTspice sim of the 150kHz transducer,
Note the slow build up in resonance and after ringing.
E

 

555 is in my comfort zone at my present level of knowledge,just to get started on this

Understood, but a 555 is unlikely to reliably provide a 1m pulse without drifting to wider or narrower pulse.
Good luck with your project.

 

no external transistor

Since the schematic in #17 is acceptable, and it has an external transistor, ah gots to know -

When you started this thread, where did you see a possible need for an external transistor? And, why was that transistor not desirable?

ak

 

Since the schematic in #17 is acceptable, and it has an external transistor, ah gots to know -

When you started this thread, where did you see a possible need for an external transistor? And, why was that transistor not desirable?

ak

The first "google stuff "all had a transistor in the timing circuit for the second 555. But That not necessary.The problem now is the 10,000 to 1 ratio between t1 and t2 times in the first 555. The resistors will need to be 1meg and 100Ohms might not work to well(with diode across R2) .Plan to build one this weekend and see

 

Hi David.
This is a LTspice sim of the 150kHz transducer,
Note the slow build up in resonance and after ringing.
E
View attachment 258833View attachment 258834

Thanks great info.
So how do I connect 555 to Transducer
I was going to current amplify using transistor common collector and pulse transformer replacing Re in diagram below
to impendence match to the transducer(do I need a LC tank in there to up the voltage(Transducer spec says 12 Volts)

thanks
David

 

Hi below is the transducer I am planing to buy.
It says Power output: 100w + pulse
So what does this mean?
The 555 can do about 150ma at 10 volts(maybe) that's 1.5watts(super low duty cycle on the output, burst of 10 to 30 millsecs)
So do I need to raise this to say 50watts?

if so will simple common collector with pulse transformer do the job?

thanks

David






Nasa 150Khz Depth Transducer
Replacement depth transducer with 7m of cable.
• Supply voltage: 12V DC
• Power consumption: nominal 120mA
• Power output: 100w + pulse
• Operating frequency: nominal 150kHz
• Dimensions: Length Overall: 106mm, Face Dia: 38mm, Thread Dia: 16mm
Suitable for use with Nasa Clipper, Target & Stingray instruments.
For In-Hull mounting kit see product code: 220035, for Thru-Hull mounting kit see product code: 220048

 

Hi David,
Wind a small auto transformer, say on a RM10 ferrite core, as a step up transformer.
This PDF has info on winding etc.

E
BTW:
If you would like to confirm that I am conversant with depth sounders,
check the Information in my AAC Profile.

 

Hi David,
Wind a small auto transformer, say on a RM10 ferrite core, as a step up transformer.
This PDF has info on winding etc.

E
BTW:
If you would like to confirm that I am conversant with depth sounders,
check the Information in my AAC Profile.

I have some purpose built pulse transformers, I thought they would do the job?
I hope to built the burst generator this week end.
I also bought some 160khz vaporising transducers(5 for £5) I wonder if they will work as a receiving element for testing
if i stick on the end of the transducer!!!

Thanks for all your help
David

 

Hi David.
This is a LTspice sim of the 150kHz transducer,
Note the slow build up in resonance and after ringing.
E
View attachment 258833View attachment 258834

Hi Eric(again)

Ok so it looks to me like I had a complete misunderstanding how the transducer element works.
I thought you just put a pulse into it, but from ltspice sim above it looks like the transducer need a 12volt dc supply
and the pulse is added on top(linear sum, no product mixing this time).Is that right?

it would explain the power rating of the transducer in the spec

• Power output: 100w + pulse

so the 100w is from the constant 12V DC supply to the Transducer.

thanks

David

 

Hi David,
It is not a constant 100W from PSU.
I will download their spec for that xdr and see what they are stating.
Nasa 150Khz Depth Transducer
E

 

Hi David.
Checked the online info.
What the spec is saying
Supply voltage: 12V DC
• Power consumption: nominal 120mA
• Power output: 100w + pulse

Nominal Power: 12V * 0.12A = 1.44Watts

Capable of handling up to 100W Pulsed power.
eg: 10ms pulse, say every 0.1Sec at a higher driver voltage.
As I said earlier, use a 12V to Higher voltage auto transformer drive,

It is a general purpose Yacht type transducer.
E
Typical example.

 

Hi David.
Checked the online info.
What the spec is saying
Supply voltage: 12V DC
• Power consumption: nominal 120mA
• Power output: 100w + pulse

Nominal Power: 12V * 0.12A = 1.44Watts

Capable of handling up to 100W Pulsed power.
eg: 10ms pulse, say every 0.1Sec at a higher driver voltage.
As I said earlier, use a 12V to Higher voltage auto transformer drive,

It is a general purpose Yacht type transducer.
E
Typical example.
View attachment 258952

That's really great Eric. many thanks David

 

Hi David,
Wind a small auto transformer, say on a RM10 ferrite core, as a step up transformer.
This PDF has info on winding etc.

E
BTW:
If you would like to confirm that I am conversant with depth sounders,
check the Information in my AAC Profile.

Hi Eric
could you reattach the pdf with the info on winding etc.
I can't find the PDF file attacment in the thread
thanks
David

 

Hi David,
Attached PDF for 'old' LM1812, has some helpful info.
Also, a couple of Draft LTspice sims of the Transducer drive.

In what way are you planning to use the Sounder project.?

http://www.dave-cushman.net/elect/rmcores.html

E

 

Hi David,
Attached PDF for 'old' LM1812, has some helpful info.
Also, a couple of Draft LTspice sims of the Transducer drive.

In what way are you planning to use the Sounder project.?

http://www.dave-cushman.net/elect/rmcores.html

EView attachment 259046View attachment 259047

Good Evening Eric and All
Had a fun day building the burst generator using 2 555 timers. It's all working well.
I had to fiddle around a bit the tune the 150khz(could not find my box of trimmer caps)
Anyway it seems to be working pretty well ant the duty cycle on the first 555 seems to be no problem.
I'm running it at 0.065 millsecs (I'll probably try and double this so I can get to 150 meter depth) period with 10 cycle burst of 150khz, I'll add some scope traces Later.

What I really am angling for(excuse the pun) is a NMEA depth for my OPEN CPN chart plotter.
I have spent a lot of time reading
USB Complete: The Developer's Guide
Book by Jan Axelson
but is extremely complicated.

Small steps and all that, I'll try to build the simple transmitter first.

By the way what's the sort of frequency tolerance on these Transducers, can the cope with a few percent error or not?

also any reason why I can't use IGBT instead of the NMOS(I got a few of them, high freq high power rating)

thanks again all

David

 

Hi David,
You can use other switching transistor types.
There is a little tolerance on the frequency spread of the transducers.

Which type of Chart Plotter are you using.?
Got it, ref video link.

Do you have a design in mind for the receiver section.?

E

 

Hi David,
You can use other switching transistor types.
There is a little tolerance on the frequency spread of the transducers.

Which type of Chart Plotter are you using.?
Got it, ref video link.

Do you have a design in mind for the receiver section.?

E

Open CPN on windows 7 pro platform.(using CMap 93 vector charts).Its an amazing piece of open source software.
I've been using it for 5 years or more.

For the reciever, Yes I have a design in mind(sort of!!!)
Single DIP Quad op amp configured as
1)buffer
2)active filter
3)amp
4)comparator
may be 2 and 3 merged or swapped arouns

Also I don't really want to use 2 transducers as I said early, but I have no real idea had to do the isolation from transmit to receive. I guess I'll need to use a Transistor driven by the output from the first 555.

thanks All
David

No Laughing please!!!

 

hi,
Post your draft receiver circuit when ready, I will run it in simulation.
You will need some method of TGA , Timed Gain Control in your receiver, also a Suppression set adjustment.

I am watching that OPENCPN video at thsi moment.
E