Been shopping around for a modern version of "The Simple Bat Detector" to essentially replace the obsolete LM386 audio amplifiers with something more up to date and...hopefully more simple.
I essentially want to modify this circuit:
http://home.earthlink.net/~bat-detector/BatDetSch.gif
I have had a browse and there seems to be few schematics as simple with a more up to date amp.
I have been thinking about using a TDA7052A:
http://www.nxp.com/documents/data_sheet/TDA7052A_AT.pdf
Bad idea?
What do you expect from a more "up to date" amplifier?
Did you notice that the data sheet for the TDA7052A is dated 1994?
I doesn't get much simpler than an LM386. Is the 386 really obsolete? Are you having trouble finding it?
The biggest problem I see with that circuit is that it needs another 386 (or something similar) on the output to drive "normal everyday" dynamic headphones.
Since when is the LM386 obsolete ? There is nothing wrong with it.
The TDA7052A seems also fine.
You could also buy a cheap amplifier module on Ebay. They cost about 1 dollar, search Ebay for : amplifier module
Isn't ultrasonic audio a contradiction?
...R
Isn't ultrasonic audio a contradiction?
I think it is a 'down-converter' that converts the detector signals into audio range so you can 'hear' objects that are detected and the frequency of the reflected signal , after conversion has a pitch that corresponds to the distance.
That's just a SWAG (scientific wild ass guess) ....... XD
Ultrasonic is just sound (audio) higher than the 20kHz humans can hear.
I think I am just whining as I have built a second circuit which does not work although it is a copy of the first! Assuming it is an LM386N-1 that has died. Got 5 more in the post on the way anyway. Luckily I have bought a second hand 40Mhz Oscilloscope which will help me with my debugging in future.
Thought I burnt out a divder as well (missed connecting a pin to ground....it got hot...fast) but pulled it out and tested it with an LED dividing a pulsed digital signal from a nano and it works. £2 saved phew!
Can you explain what the circuit does in a way that addresses Robin's point about the ultrasonic input and my point about the LM386 being an audio range (20 hz to 20khz ) amplifier ? Why does it have an audio amplifier on the output if the input is ultrasonic ? It looks like the 4024 is dividing the 40khz frequency by 16 (40khz/16=2.5khz) yielding a frequency audible by humans.
Can you confirm that ?
link=topic=255243.msg1806271#msg1806271:
Can you explain what the circuit does in a way that addresses Robin's point about the ultrasonic input and my point about the LM386 being an audio range (20 hz to 20khz ) amplifier ? Why does it have an audio amplifier on the output if the input is ultrasonic ? It looks like the 4024 is dividing the 40khz frequency by 16 (40khz/16=2.5khz) yielding a frequency audible by humans.
Can you confirm that ?
http://www.ti.com/lit/ds/symlink/lm386.pdf Page 3 - Bandwidth.
Clearly states 300Khz. You honestly think they would cap it for some strange reason at 20kHz? What do you think a High Pass filter is for?
As far as the science, ultransonic audio is short for "sound waves over the human hearing frequency range". Bats, for example, range from 20Khz to just over 100Khz.
The LM386N chips amplify the signals from the 40Khz sensitive transducer (40Khz is the most sensitive band of it) and passes it to the divider which will take the signal and divide the frequency by 16 to give a human audible ouput.
50KHz becomes around 3.1Khz (well within human range).
IMHO, both alternative LM386 and TDA7052 are wrong . I would search a low noise amplifier, there are microchip MCP6021/2/4 for example. Power amplifier may works as a second stage. Old OPA NE5532 or NE5534 can still be competitive.
Clearly states 300Khz. You honestly think they would cap it for some strange reason at 20kHz? What do you think a High Pass filter is for?
Thanks for that answer. Excuse my ignorance. You are certainly justified in correcting my incorrect statement , although I'm not sure it is necessary to talk down to me . The purpose of this forum is not just to help you with your circuit. It is to help others learn. Thus when you post here you invite question and comments. It is up to you to decide how to respond to these. I don't think your reponse is really appropriate considering the question you were asking was:
Can you explain what the circuit does in a way that addresses Robin's point about the ultrasonic input and my point about the LM386 being an audio range (20 hz to 20khz ) amplifier ? Why does it have an audio amplifier on the output if the input is ultrasonic ? I
Your answer about the LM386 was right on (BW=300khz) , but I think you missed the fact that I got it backwards. The LM386 is actually on the INPUT and not the OUTPUT . I think an appropriate response would have been your comment about the BW
and a correction about where the LM386 was and what exactly it is doing, (meaning stage-1 has a gain of 200 and stage-2 has a gain of 20 for a total of 4000 and also that it is a High Pass filter. I'm not whining or being sensitive but was this really necessary ?
What do you think a High Pass filter is for?
considering the question you were answering was this:
Can you explain what the circuit does ?
If I knew it was a high pass filter would I be asking you to explain the circuit ?
I think "The LM386 is a H/P filter with a two stage gain of 4000" would have sufficed. No matter where you go there is always going to be someone smarter than you. One would hope they don't rub it in. I'm just saying there's no need to be cocky.
The LM386N chips amplify the signals from the 40Khz sensitive transducer (40Khz is the most sensitive band of it) and passes it to the divider
As far as I can tell from page 2 of the datasheet, IC-1 is a Gain, of 200 and IC-2 is a Gain. of 20 for a total gain of 4000.
This is probably necessary due to the low amplitude of the bat signals or because of the diissipation of the amplitude over distance between the bat and the detector. Maybe it is a long-range bat detector. in any case the amplification needs to get the signal to a level that will clock the CMOS 7-stage Ripple-Carry Binary counter.
It is an ultrasonic to audio down converter as I stated here :
It looks like the 4024 is dividing the 40khz frequency by 16 (40khz/16=2.5khz) yielding a frequency audible by humans.
Can you confirm that ?
which is basically what you are saying here ;
The LM386N chips amplify the signals from the 40Khz sensitive transducer (40Khz is the most sensitive band of it) and passes it to the divider which will take the signal and divide the frequency by 16 to give a human audible ouput.
50KHz becomes around 3.1Khz (well within human range).
The difference being my estimation of the audio output frequency was a bit off (2.5khz vs 3.1 khz) because I used 40khz for my calculation instead of 50khz. (I'm not bat-savy)