Bat detector
- Thread starter DD4WH
- Start date
Hi,
I could use some advice on building the detector with Edwin's excellent PCB. What difference would it make in practice if I mounted the audio board and teensy with pin headers and sockets on the reverse of the PCB rather than using the resistors? I understand I would expect more noise but would the unit be unusable for casual listening and recording?
I ask because I just put the whole project together and it worked briefly. But then I shorted out a pin on the teensy/audio assembly with the SD Card socket on the display(dumb dumb dumb). I have taken off the teensy and audio board, I think the problem is the audio board but not 100% sure. I will replace the audio board but dont want to end up having to take it apart again.
Many thanks for any guidance
Jim
I could use some advice on building the detector with Edwin's excellent PCB. What difference would it make in practice if I mounted the audio board and teensy with pin headers and sockets on the reverse of the PCB rather than using the resistors? I understand I would expect more noise but would the unit be unusable for casual listening and recording?
I ask because I just put the whole project together and it worked briefly. But then I shorted out a pin on the teensy/audio assembly with the SD Card socket on the display(dumb dumb dumb). I have taken off the teensy and audio board, I think the problem is the audio board but not 100% sure. I will replace the audio board but dont want to end up having to take it apart again.
Many thanks for any guidance
Jim
Hi Jim,
Sorry to hear you damaged something.
What is still working, and what is not working right now?
There is a small fuse on the teensy, so if that blew you might be able to fix it.
You can uses pinheaders, the resistors are just to keep the noise out. If you turn up het gain the display will start scroling so you loose a bit of sensitivity and recordings do not look as good as with the resistors but it will still work with header pins. Oh, and the whole package will be much thicker of course. I know Corbee also built one this way so the Teensy could be pulled of the mainboard.
Edwin
Sorry to hear you damaged something.
What is still working, and what is not working right now?
There is a small fuse on the teensy, so if that blew you might be able to fix it.
You can uses pinheaders, the resistors are just to keep the noise out. If you turn up het gain the display will start scroling so you loose a bit of sensitivity and recordings do not look as good as with the resistors but it will still work with header pins. Oh, and the whole package will be much thicker of course. I know Corbee also built one this way so the Teensy could be pulled of the mainboard.
Edwin
Hello Edwin, thank you for getting back to me and so quickly.
The teensy seems to be OK as far as I can determine, no way to test all the pins though without the circuit working. I concluded it was probably the audio board but I cant be sure.
Thank you for the advice, I will try with pin headers this time.... very carefully. I am very much looking forward to getting this going, its an excellent project. Even my wife is interested which is a first for my tinkering with electronics.
Jim
The teensy seems to be OK as far as I can determine, no way to test all the pins though without the circuit working. I concluded it was probably the audio board but I cant be sure.
Thank you for the advice, I will try with pin headers this time.... very carefully. I am very much looking forward to getting this going, its an excellent project. Even my wife is interested which is a first for my tinkering with electronics.
Jim
Hello Cor,
that is very neat. I hope the noise levels are reasonable. I plan something very similar but am trying to put use sockets so I can remove either board it goes pear shaped again. I found some extra long headers which should allow that. I will post a photo if it works.
Jim
that is very neat. I hope the noise levels are reasonable. I plan something very similar but am trying to put use sockets so I can remove either board it goes pear shaped again. I found some extra long headers which should allow that. I will post a photo if it works.
Jim
I would not expect the audioboard to get into trouble when you make a short on the teensy board.
Did you lose microphone audio, or headphone (playback) or both?
If the teensy does not "talk" to the audioboard the problem could still be in the teensy.
Just check the voltages on the Teensy, audioboard and mainboard before you rip it apart, or did you already disassemble the detector.
Edwin
Did you lose microphone audio, or headphone (playback) or both?
If the teensy does not "talk" to the audioboard the problem could still be in the teensy.
Just check the voltages on the Teensy, audioboard and mainboard before you rip it apart, or did you already disassemble the detector.
Edwin
Hi Edwin,
Yes, I took it apart. The 3.2 volts on the main board was going straight to ground. So it was dead with board power. As I say, the teensy powered up via USB and definitely at least partly working.
As it happens I was using a current limited power supply set at 100ma. In hindsight perhaps I should have turned the current limiter up to 5A and watched to where the smoke came out before pulling it apart. Hey ho, these things happen.
Jim
Yes, I took it apart. The 3.2 volts on the main board was going straight to ground. So it was dead with board power. As I say, the teensy powered up via USB and definitely at least partly working.
As it happens I was using a current limited power supply set at 100ma. In hindsight perhaps I should have turned the current limiter up to 5A and watched to where the smoke came out before pulling it apart. Hey ho, these things happen.
Jim
CorBee
Well-known member
Hi Justin,
As I am slowly waking up from hibernation Ive picked up on this part. The bat_sd you have shared helped a great deal, only one var was not declared tRecStart. Its early days still but the next version will probably have guan fields added to each wave file. Thanks for guiding us and sharing the initial code.
Regards
Cor
CorBee
Well-known member
Hi,
An update on the work thusfar in this season. Edwin has been testing adding a GPS and a temperaturesensor in the same default housing we are using for some time.
Hasnt been easy due to the limited space but it seems he has both the hardware and the software working now. I will share the update of the software allowing this later this month.
Additionally the support for the GUANO format when saving wave-files has been further extended, both GPS and temperature are also recorded.
regards
Cor
An update on the work thusfar in this season. Edwin has been testing adding a GPS and a temperaturesensor in the same default housing we are using for some time.
Hasnt been easy due to the limited space but it seems he has both the hardware and the software working now. I will share the update of the software allowing this later this month.
Additionally the support for the GUANO format when saving wave-files has been further extended, both GPS and temperature are also recorded.
regards
Cor
The GPS turned out to be quite a struggle. The code running in the Teensy and all the data lines being switched make a lot of noise. The GPS unit is very close to the busy Teensy and has problems with RFI. You have to shield the Teensy with a piece it tin plate. I bent a U shape and put it over the length of the Teensy.
I soldered it to the GND plane of the main PCB and to the GND pin near the micro USB connector.
I will post pictures later how this fits in the detector. In the attached schematic you can see how the GPS and DS18B20 sensor can be connected.
I only tried a few GPS units. Starting out with ATGM336H I quickly realized GPS reception would be a problem so I also tried a G18U8TTL, Beitian BN-180 and Ublox Neo8. Of these four the Beitian seemed to have the best immunity but I am not done testing. I hope an other NEO7 with antenna on the PCB and a variant like that could work just as well or even better. I am sure your sat-nav (the one you stick to the windshield of your car) will work better. It would have been nice if the GPS was further away form the busy Teensy. If we want better reception in this small box we need to make better shielding or use something that absorbs the RFI.
I hope to be able to post some pictures soon.
Kind regards,
Edwin
I soldered it to the GND plane of the main PCB and to the GND pin near the micro USB connector.
I will post pictures later how this fits in the detector. In the attached schematic you can see how the GPS and DS18B20 sensor can be connected.
I only tried a few GPS units. Starting out with ATGM336H I quickly realized GPS reception would be a problem so I also tried a G18U8TTL, Beitian BN-180 and Ublox Neo8. Of these four the Beitian seemed to have the best immunity but I am not done testing. I hope an other NEO7 with antenna on the PCB and a variant like that could work just as well or even better. I am sure your sat-nav (the one you stick to the windshield of your car) will work better. It would have been nice if the GPS was further away form the busy Teensy. If we want better reception in this small box we need to make better shielding or use something that absorbs the RFI.
I hope to be able to post some pictures soon.
Kind regards,
Edwin
As promised a few pictures....
Notice the ferrtite bead on the wires of the GPS module this to help keep the RFI out. I also use a switch in the GPS powerline. The GPS unit draws quite a bit of curent, if I do not need GPS info I can save battery power.
If someone has the chance to test other GPS devices and fonds one that works better please let us know.
If I wrote something funny it probably was the autocorrupt function in my smartphone.
Edwin
Notice the ferrtite bead on the wires of the GPS module this to help keep the RFI out. I also use a switch in the GPS powerline. The GPS unit draws quite a bit of curent, if I do not need GPS info I can save battery power.
If someone has the chance to test other GPS devices and fonds one that works better please let us know.
If I wrote something funny it probably was the autocorrupt function in my smartphone.
Edwin
Sorry I am so late to this party, but I only accidentally discovered this project last week. Actually, I was possibly too early as I had an idea to build a similar bat detector with FFT & frequency spectrum display, as an interesting project to use the Arduino Zero when it was released (2015). Unfortunately I'm a digital sort of guy and gave up when I realised the amount of analogue circuitry it would need. (I think I found an I2S MEMS microphone and considered just hooking that up directly, but it had poor ultrasound response.) So you can imagine my excitement when I discovered your project. To give you a clue, I ordered one of Edwin's boards immediately and spent this weekend reading this entire thread (which confirmed my initial thoughts with all the talk of high-pass and low-pass filters, along with gain, pre-amps and ground loops - analogue is scary) and trying to source the rest of the components I will need. Which brings me on the my first question.
The parts list specified "LP2950Z 100 mA, Low Power Low Dropout Voltage Regulator", but I cannot find one anywhere. I started trying to find a replacement, but became confused when I found a datasheet which suggested it has a 5v output, but according to the schematic it is used to drive the 3v3 line! (I told you analogue was scary
Can you recommend a more readily available alternative?
Next I am struggling with the low esr capacitors. The only ones I can find are either surface mount or don't have the 2.54mm pitch. Can you suggest a manufacturer/series I should look for? (I could bend the leads a bit, but it won't sit so neatly on the board.)
This one is not exactly a problem, just wondering which is best. There is no specification for the resistors in the parts list (other than 1/8W for the header ones). I assume 1/4W will be fine for the rest. Is there any preference for carbon/metal film etc? (I believe metal ones have lower noise.) Am I worrying too much? (I will not be making millions of these, so spending a little extra on the best/most reliable components makes sense to me.)
I hope the final question is not too silly. It occurred to me that the audio board could be slung under the main board, making the sandwich:
Display
Teensy MCU
Teensybat
Teensy Audio
That would place the audio further away from the noise sources, at the expanse of making it a little thicker. Would that work and would there be any advantage, or is it a silly idea? (I'll probably be able to answer this myself when all the bits arrive.)
Hopefully I will have this built and working before the bats wake up.
--
David
The parts list specified "LP2950Z 100 mA, Low Power Low Dropout Voltage Regulator", but I cannot find one anywhere. I started trying to find a replacement, but became confused when I found a datasheet which suggested it has a 5v output, but according to the schematic it is used to drive the 3v3 line! (I told you analogue was scary
Can you recommend a more readily available alternative?Next I am struggling with the low esr capacitors. The only ones I can find are either surface mount or don't have the 2.54mm pitch. Can you suggest a manufacturer/series I should look for? (I could bend the leads a bit, but it won't sit so neatly on the board.)
This one is not exactly a problem, just wondering which is best. There is no specification for the resistors in the parts list (other than 1/8W for the header ones). I assume 1/4W will be fine for the rest. Is there any preference for carbon/metal film etc? (I believe metal ones have lower noise.) Am I worrying too much? (I will not be making millions of these, so spending a little extra on the best/most reliable components makes sense to me.)
I hope the final question is not too silly. It occurred to me that the audio board could be slung under the main board, making the sandwich:
Display
Teensy MCU
Teensybat
Teensy Audio
That would place the audio further away from the noise sources, at the expanse of making it a little thicker. Would that work and would there be any advantage, or is it a silly idea? (I'll probably be able to answer this myself when all the bits arrive.)
Hopefully I will have this built and working before the bats wake up.
--
David
The LP2950 is 5V and is the wrong part number on the schematic as far as I can see - you need a 3.3V output regulator
in that position or bad things happen. Its not uncommon to see the wrong part number in a schematic as people are
lazy about creating a new device definition in the middle of laying out a PCB.... My goto LDO regulator series is the 1117
(available in several voltages), but it depends what PCB footprint was used.
in that position or bad things happen. Its not uncommon to see the wrong part number in a schematic as people are
lazy about creating a new device definition in the middle of laying out a PCB.... My goto LDO regulator series is the 1117
(available in several voltages), but it depends what PCB footprint was used.
CorBee
Well-known member
Sorry I am so late to this party, but I only accidentally discovered this project last week. Actually, I was possibly too early as I had an idea to build a similar bat detector with FFT & frequency spectrum display, as an interesting project to use the Arduino Zero when it was released (2015). Unfortunately I'm a digital sort of guy and gave up when I realised the amount of analogue circuitry it would need. (I think I found an I2S MEMS microphone and considered just hooking that up directly, but it had poor ultrasound response.) So you can imagine my excitement when I discovered your project. To give you a clue, I ordered one of Edwin's boards immediately and spent this weekend reading this entire thread (which confirmed my initial thoughts with all the talk of high-pass and low-pass filters, along with gain, pre-amps and ground loops - analogue is scary) and trying to source the rest of the components I will need. Which brings me on the my first question.
The parts list specified "LP2950Z 100 mA, Low Power Low Dropout Voltage Regulator", but I cannot find one anywhere. I started trying to find a replacement, but became confused when I found a datasheet which suggested it has a 5v output, but according to the schematic it is used to drive the 3v3 line! (I told you analogue was scary
Next I am struggling with the low esr capacitors. The only ones I can find are either surface mount or don't have the 2.54mm pitch. Can you suggest a manufacturer/series I should look for? (I could bend the leads a bit, but it won't sit so neatly on the board.)
This one is not exactly a problem, just wondering which is best. There is no specification for the resistors in the parts list (other than 1/8W for the header ones). I assume 1/4W will be fine for the rest. Is there any preference for carbon/metal film etc? (I believe metal ones have lower noise.) Am I worrying too much? (I will not be making millions of these, so spending a little extra on the best/most reliable components makes sense to me.)
I hope the final question is not too silly. It occurred to me that the audio board could be slung under the main board, making the sandwich:
Display
Teensy MCU
Teensybat
Teensy Audio
That would place the audio further away from the noise sources, at the expanse of making it a little thicker. Would that work and would there be any advantage, or is it a silly idea? (I'll probably be able to answer this myself when all the bits arrive.)
Hopefully I will have this built and working before the bats wake up.
--
David
Hi David,
Welcome aboard. These are questions where I hope Edwin will have the definitive answers. As to the sandwich, Ive started with a very wide setup with headers between all parts that looks more or less like your sandwich. I think its all possible but it also boils down to "how does it fit in a box", "how easy is it to build".r
regards
Cor
Hi David,
You are too late, the bats just woke up last evening... well at least here they did, I heard some pipistrelle, serotinte and plecauri but I guess that is just because of the warm weather we suddenly have here.
Also I just posted the board this morning. I could have thrown in some parts.....
The LP2950 is available in 3.0, 3.3 and 5 volts, LP2950-33 should be quite common any other LDO like mcp1700 3v3 can be used but observe the pinout! (The lower the noise the better)
The caps I use are Suncon SWG series 7mm high.
Moving the audioboard to the underside of the mainboard is not a bad idea, I do not know how much this will help because I have not tried it. I guess the whole stack would probably not fit in the houding I use. It will also bring the audioboard closer to some others I use like the powerbank PCB and a bluetooth board which I also have mounted on the lower side of the mainboard. (seems to be a bad noisemaker, which turns on slowly when sound is played. I have not shared any info on the bluetooth board because of that)
The dampening resistors are 1/8 or 1/6w, mainly chosen because the 1/4w resistors are quite long. I used 1/4 resistors on all other positions. I think carbon film resistors would be fine, if you do have the choice, metal oxide resistors should be lower noise so chose those.
Kind regards,
Edwin
You are too late, the bats just woke up last evening... well at least here they did, I heard some pipistrelle, serotinte and plecauri but I guess that is just because of the warm weather we suddenly have here.
Also I just posted the board this morning. I could have thrown in some parts.....
The LP2950 is available in 3.0, 3.3 and 5 volts, LP2950-33 should be quite common any other LDO like mcp1700 3v3 can be used but observe the pinout! (The lower the noise the better)
The caps I use are Suncon SWG series 7mm high.
Moving the audioboard to the underside of the mainboard is not a bad idea, I do not know how much this will help because I have not tried it. I guess the whole stack would probably not fit in the houding I use. It will also bring the audioboard closer to some others I use like the powerbank PCB and a bluetooth board which I also have mounted on the lower side of the mainboard. (seems to be a bad noisemaker, which turns on slowly when sound is played. I have not shared any info on the bluetooth board because of that)
The dampening resistors are 1/8 or 1/6w, mainly chosen because the 1/4w resistors are quite long. I used 1/4 resistors on all other positions. I think carbon film resistors would be fine, if you do have the choice, metal oxide resistors should be lower noise so chose those.
Kind regards,
Edwin
Thanks Edwin. That worked better. Your parts list has LP2950Z which produced no hits. I'll see is I can order the rest of the parts tomorrow and see if I can beat the bats.
I don't know why I have the Z version in the parts list. Probably because the CAD program lists that one an not the 3, 3.3 and 5V versions but the Z as generic. If I have to work on the manual I will update the partslist. If you have any other suggestions for the construction manual, please send me an e-mail. (callsign) at gmail dot com will work just fine.
Kind regards Edwin
PE1PWF
Kind regards Edwin
PE1PWF
That sounds interesting. I have been thinking about this while waiting for all my parts to arrive. Are you using a module like HC-05/06? I was wondering about using an ESP32 as a co-processor (it would relieve the teensy of extra load - I assume it is very busy with the DSP - and has WiFi as well an Bluetooth). This would allow connection to a smart phone as well as even the internet, which would open up many possibilities:
- Playback to a bluetooth speaker (so you can sit indoors and wait for activity)
- Stream the audio live to the internet
- Connect sensors (you mentioned GPS and Temp/RH)
- Use a Bluetooth GPS (or get position from a phone)
- Upload recording files
- Send data to some AI to identify the bats
- Have a phone app to provide a bigger display and possibly extra controls
- Probably lots more!
I just used a small bluetooth audio transmitter/receiver bought for a few bucks on aliexpress. It uses an usb connector for powersupply and has two audio jacks. One is for the RX and one for the TX function. A small switch on the device can change the function of receiver or transmitter. The jackplug makes a switch that turns it on.
So nothing fancy I'm affraid.
I also use this to listen indoors and have the detector outside. Unfortunately I could not get the bluetooth RF signal out of the audio. I don't know what happens but as soon as I applied power to the unit I see a lot of noise. Before I was able to use it, but since I rebuilt my detector I can't get the noise out.
I now just have the bluetooth module plugged in a powerbank and a cable connected to the headphones jack. Of course you could also bring a wire into the house an simply connect to a line in of a portable speaker.
What you are suggesting (dwd) looks a lot more interesting but also quite complex I won't stop you if you are trying to build something like that but I'm afraid I can't help you it is not my cup of tea.
Kind regards,
Edwin
So nothing fancy I'm affraid.
I also use this to listen indoors and have the detector outside. Unfortunately I could not get the bluetooth RF signal out of the audio. I don't know what happens but as soon as I applied power to the unit I see a lot of noise. Before I was able to use it, but since I rebuilt my detector I can't get the noise out.
I now just have the bluetooth module plugged in a powerbank and a cable connected to the headphones jack. Of course you could also bring a wire into the house an simply connect to a line in of a portable speaker.
What you are suggesting (dwd) looks a lot more interesting but also quite complex I won't stop you if you are trying to build something like that but I'm afraid I can't help you it is not my cup of tea.
Kind regards,
Edwin