Please note: All our kits will be sold via The Curious Electric Company from now on. This page is for information only. Please visit our shop to see our current range of kits or contact us to discuss your project and how we might be able to help.

Welcome to fascinating world of bats! This bat detector device converts ultrasonic sounds created by bats and convert them down to a lower frequency so that we humans can hear them.

Bats use ultra-sonic pulses to navigate and to detect prey. These pulses are very high pitch (around 5 times the maximum frequency humans can hear). This electronic circuit converts the high pitched sounds produced by bats to a human-audible level. It can also be used to listen to other high frequencies such as peeling sticky tape, compact fluorescent lights and power supplies.

This kit costs £20 for professional circuit board and all electronic components. This includes free P&P within the UK.

Here are all the parts included in the kit – quite a few of them!

Here are the printed circuit boards from this kit.

A completed circuit board.

Another interesting use for this detector is to investigate devices which make a high frequency noise (in the region of 40-120kHz). You can hear compact fluorescent lights screaming away, the squeaks from sellotape as it is unwrapped and the high frequency power supplies which power the back-lights in phones and laptops.

Buy it here

A PCB and kit of electronic parts is available to buy for £20 (including delivery within the UK) via our sister company: The Curious Electric Company. This does not include the enclosure.

Please note: While not difficult to make, this kit does require quite a lot of soldering. It is recommended for people who have already done a bit of soldering and will take in the region of 1-4 hours to solder.

Edit 12/9/13: We have now designed a laser cut wooden enclosure for this kit. It can be purchased with the kit or on its own.Plans for this enclosure are available here.

Instructions

Here are the bat detector instructions:

Download the PDF file .

Enclosure design

A laser-cut enclosure is available for this kit and looks like this (more details are here):

Check out this awesome version made by Bart, who used the enclosure plans above but made it out of clear acrylic:

You can also fit the circuit into your own enclosure.

The circuit board was designed to fit into easily available 40mm push-fit plumbing fittings as shown here:

The finished unit, using 40mm plumbing tubing as a case.

But other people have used different cases – please use whatever is available:

Here is anther bat listener built by Dick Stomp to test insect repellers (which emilt similar frequencies):

Another bat detector and enclosure:

A bat listener using the pipe and push-fit connections enclosure:

Great lettering and speaker grill on this case!

31 responses to “Bat Detector

  1. Hi Antonio,
    Yes delivery to Spain is possible. It would cost £3.50 for postage and packing (so £23.50 in total).
    Regards,

    Matt

    Quoting Guest:Hi

    I wonder if you can send Murcielago Kit to Spain.
    Being possible, how much would it cost?.

    regards

    Antonio Martin

  2. Quoting Guest:Hi.

    I am interested.
    If you can send bat detector kit to Finland, what is total price?

    Regards Juha

    Hi,
    Thanks for your interest.
    The postage to Finland would be £3.
    I have just emailed you a paypal invoice, if you would like to order one.
    Cheers,

    Matt

  3. Postage to Italy would be £3 via Royal Mail.
    Regards,
    Matt

    Quoting Guest:Hi
    I’m interested
    I live in italy
    how much for the postage?
    thank you
    Regards
    Marzia

  4. Very nice project.
    What is the shipping cost to Oslo, Norway ?

    I can pay by VISA,Mastercard,Diners Club or other methods.
    Can you ship the kit to me before the season ends ?

    regards,

    Ola

    Oslo Norway

  5. I’ve updated the ‘but it now’ button to give options for buying the kit in diffeent areas of the world.
    I try to send things out as soon as I can (generally within 2 or 3 days). Delivery time will depend upon the carrier.
    Regards,
    Matt

    Quoting Guest:Very nice project.
    What is the shipping cost to Oslo, Norway ?

    I can pay by VISA,Mastercard,Diners Club or other methods.
    Can you ship the kit to me before the season ends ?

    regards,

    Ola

    Oslo Norway

  6. Hello, nice kit i think.
    Does it scan the frequencys by itself or is it possible to adjust?
    Is it also possible to adjust the volume?
    Thank you
    Bart

  7. Hi Bart,
    The circuit detects a range of frequencies, but it is not possible to adjust. Basically the ultrasonic sensor ‘hears’ everything. This is then amplified and put through a low pass filter (removing anything > 160kHz) and a high pass filter (which removes anything

  8. #11 Matthew Little 2013-09-09 15:59
    Hi Bart,
    The circuit detects a range of frequencies, but it is not possible to adjust. Basically the ultrasonic sensor ‘hears’ everything. This is then amplified and put through a low pass filter (removing anything > 160kHz) and a high pass filter (which removes anything

    Perfect, i gonna place my order tomorrow evening 🙂

  9. Hello,

    It seems to be an intersting device! But first I have some technical questions:

    -is it possible to wire an output jack in place of the intended speaker? Is there a need to place or swap a resistor?
    -RV1 is the volume control?
    -any modification possible to tune the frequency? Like a pot between the oscillator IC?

    Thanks and best wishes,
    Alex

  10. Hi Alex,
    To try and answer your qeustions:

    Yes – you could wire an output jack (for headphones/amplification) rather than the speaker. It depends what you are driving with this. With typical headphones I would suggest you do not need to add a resistor. If you are putting the output into an amplifier then I think you would need to restrict to output with a resistor (although I am unsure without more research the value to use).

    RV1 is not the volume control – rather the sensitivity control. This is adjusted for the background level of ultrasonic noise, so that anything louder than the background will be heard.
    If the RV1 value is low then the device ‘squeals’ as it picks up its own ultrasonic noise. Adjust this until it does not feedback. That is the most sensitive set-point.

    There is no way to tune the frequency with a pot. This is a pretty simple frequency divider (rather than a more complex heterdyne). Basically for every 8 pulses put into the device only 1 will appear at the output. Hence the ultrasonic pulses (in the region of 40-80kHz) will be stepped down to 5-10kHz and hence we can hear them.

    The step down ratio could be adjusted by changing the output pin from the 4024 ripple counter. I have never tried this.

    I hope that helps – let me know if you have any more questions,
    Regards,

    Matt

    Quoting Guest:Hello,

    It seems to be an intersting device! But first I have some technical questions:

    -is it possible to wire an output jack in place of the intended speaker? Is there a need to place or swap a resistor?
    -RV1 is the volume control?
    -any modification possible to tune the frequency? Like a pot between the oscillator IC?

    Thanks and best wishes,
    Alex

  11. Quoting Guest:Looks interesting. Which Ultrasonic Receiver are you using?

    Hi, Thanks for your comment.
    The kit uses this ultrasonic receiver, obtained from Rapid electronics: http://www.rapidonline.com/Electronic-Components/Ultrasonic-Transducers-30210
    Code: 35-0180
    It has a resonant frequency of 40kHz, but seems to work OK in the range required for bats: 15kHz-120kHz. Different bat species use different frequencies and in some of the more professional bat detectors (I’m afraid not this kit) the detection frequency can be tuned to help identify the bat species.
    Hope that helps, Matt.

  12. Hi Antonio,

    Yes – I can provide just the PCB, but the cost will be affected by the postage price (which is almost the same as for the full kit) – it would cost £7 including p&p to Spain.
    Regards,

    Matt

    Quoting Guest:It is posible by just PCBs ?…
    Thanks in advance

    Antonio

    Madrid

    Spain

  13. Quoting Guest:So its 3 pounds to extra for shipping to the Netherlands 🙂 ?

    Yes – Thats right +£3 for P&P to anywhere in Europe, via Royal Mail air mail. Cheers. Matt

  14. Just a belated note to say that I received the detector very promptly and within a couple of hours had built it with my 5 year old son having helped identify components and place on board. An hour or so afterwards the bats which visit our garden proved everything was working well. Andrew was delighted (even if rather tired) and took it to show his school friends the following morning! Many thanks.

  15. Hi

    Won’t any frequency corresponding to a multiple the 1:8 sampling rate disappear? Wouldn’t the frequency response profile have valleys centered on these frequencies?

    Craig

  16. Hi

    What can you say about the actual or theoretical frequency response of this system? I guess I would expect valleys around multiples of the 1/8 sampling frequency, but I’m really not an expert on this. I purchased it to see if I could hear the squirrels in the attic talking.

  17. Quoting Craig Hicks:Hi

    Won’t any frequency corresponding to a multiple the 1:8 sampling rate disappear? Wouldn’t the frequency response profile have valleys centered on these frequencies?

    Craig

    Hi Craig,
    Thanks for your order.
    As you have seen, this circuit is pretty simple in the way it works – the signal is amplified greatly and filtered (high pass and low pass). The amplified signal basically becomes a series of on/off pulses which are fed into the counter and every 8th pulse is outputted to the speaker.

    So an input of 40kHz will give a 5kHz output.
    Some frequency information is definitely lost with this rough way of frequency step-down. The reason that you dont get valleys of lost frequencies is that the signal is converted into an On/Off digital pulse train before the step down counter and the output is just a series of on/off clicks.

    I have tried this unit directly against a much more expensive heterodyne frequency selectable unit (my partner uses these for professional bat surveys) and I could hear virtually no difference in the output sounds. In fact I would have said this kit was more sensitive. The main benifit of the professional unit is the frequency range selection, which aids with species selection.
    Another issue with this kit which uses an ultrasonic receiver is the sensitivity range of the receiver, which has a peak around 40kHz, but again it works well over a very wide range of input signals as the analog signal is converted into a digital pulse train.

    I hope that helps – basically this is a simple and low cost unit which will probably loose the fine detail of the Bat signals, but has worked very well in practice.

    Regards, Matt

  18. Quoting David:Hi, could the detector be modified to have a LCD freq display!!

    Hi David,
    Yes – I’ve been thinking about counting the frequency and displaying it for a while. If you count the pulses after the digital counter IC (pin 6 of the 4024) and then multiply that by 8 that will give the input frequency. This could be counted using a microcontroller (such as an Arduino) and then displayed after a bit of averaging.
    Let me know if you build this – I’d love to see it.
    When I have a moment I might try this out, as thinking it through, its not too difficult.
    Have fun with you kit and thanks for your order.
    Regards, Matt

  19. Fantastic. Got the kit yesterday morning by the post, my husband and our 8-year old daughter assembled it this afternoon, fitted it in a 40 mm waste pipe as shown in the picture (excepted that it is shorter, 22 cm long in total) and it seems to be working fine. Looking towards hearing for the first time tonight the bats that we have seen in our garden!

    Only one little comment regarding the instructions: the colour codes for some resistances are not right…

  20. Hi!

    Just got the kit and keen to get started :-). Couple of questions:
    Does it matter which way round the ultrasonic receiver is installed? If yes which pin is ground?

    In the instructions it says: “This device can be tuned to different frequencies of different species of bat”. How do you do this? I am thinking that the 22k trimpot is there as a sensitivity adjuster and not as a frequency range adjuster.

    Thanks!
    Best regards
    Justin

  21. Hi Justin,
    Hope that the kit worked for you, sorry for delay in replying.
    The ultrasonic transducer does not matter which way around it is inserted.
    You are right – the trim pot is adjsuting the sensitivity, not the frequency range. This circuit cannot easily vary the fequency detected. I will adjust the instructions accordingly.

    Best regards,

    Matt

    Quoting Justin:Hi!

    Just got the kit and keen to get started :-). Couple of questions:
    Does it matter which way round the ultrasonic receiver is installed? If yes which pin is ground?

    In the instructions it says: “This device can be tuned to different frequencies of different species of bat”. How do you do this? I am thinking that the 22k trimpot is there as a sensitivity adjuster and not as a frequency range adjuster.

    Thanks!
    Best regards
    Justin

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