Bill of materials to build single π•pistrelle (recommended to build 10 at a time to achieve lowest build cost):
1x π•pistrelle baseboard printed circuit board
1x BatSignal ultrasonic module
1x Raspberry Pi Pico (available from many outlets, typically £3.50 late 2021 pricing)
1x AdaFruit SD / SPI breakout board (I get mine from Pi Hut £2.60 inc VAT late 2021 pricing)
10x 3mm 2.2v 400mcd luminosity LEDs (I usually buy mine here)
10x 470Ω resistors (for LEDs, again I buy mine here))
4x 10kΩ resistors (for ultrasonic support circuitry and SD pullup - here)
1x 27Ω resistor (for ultrasonic support circuitry - here)
2x 3.5mm headphone jacks - here
2x 12mm x 6mm push buttons - here but can often be found very cheaply on eBay
1x rotary encoder - here
2x 22µF electrolytic capacitor - here
1x 1µF electrolytic capacitor - here
2x 0.1µF tantalum bead capacitor - here
1x LM4040 voltage reference - this is not really necessary for detecting, but helps signal capture quality for field recording - here
1x solder mount battery holder for 3 AAs - here
Additionally you will need a fine-tipped soldering iron, leaded solder (lower temperature solder is essential for assembly of the BatSignal ultrasonic module), tweezers, a small pair of pliers and some fine flush-cutting wire cutters. If you have access to a Mini Hotplate and low-temperature solder paste, that will make assembly of the BatSignal much easier.
1x π•pistrelle baseboard printed circuit board
- available 10-off from PCBWay.com
- allow at least 10 days for manufacture and delivery, late 2021 pricing approx £16.50 for 10 incl FedEx delivery from China
1x BatSignal ultrasonic module
- For UK residents only :
- Bare BatSignal PCBs for self-assembly are available directly from me for £5 plus postage for a panel of PCBs - email me for details
- For UK residents who wish to buy pre-assembled BatSignal modules, they are also occasionally available directly from me with at least 3 weeks lead time as I may need to order components and bare PCBs
- Cost of assembled, tested BatSignal modules is £50 plus postage for 10 units - again, email me for details and availability
- For those outside the UK :
- Sadly there there is no easy option, other than buying a HUGE number of PCBs
- 10x panels of 24 PCBS i.e 240 PCBs (order includes a solder stencil) - from PCBWay.com
- Sadly there there is no easy option, other than buying a HUGE number of PCBs
- 1x Knowles ultrasonic microphone (these can be found very cheaply on eBay from China, otherwise here)
- 1x ultrasonic op amp (I use Analog Devices opampyultrathingy240 - available here)
1x Raspberry Pi Pico (available from many outlets, typically £3.50 late 2021 pricing)
1x AdaFruit SD / SPI breakout board (I get mine from Pi Hut £2.60 inc VAT late 2021 pricing)
10x 3mm 2.2v 400mcd luminosity LEDs (I usually buy mine here)
10x 470Ω resistors (for LEDs, again I buy mine here))
4x 10kΩ resistors (for ultrasonic support circuitry and SD pullup - here)
1x 27Ω resistor (for ultrasonic support circuitry - here)
2x 3.5mm headphone jacks - here
2x 12mm x 6mm push buttons - here but can often be found very cheaply on eBay
1x rotary encoder - here
2x 22µF electrolytic capacitor - here
1x 1µF electrolytic capacitor - here
2x 0.1µF tantalum bead capacitor - here
1x LM4040 voltage reference - this is not really necessary for detecting, but helps signal capture quality for field recording - here
1x solder mount battery holder for 3 AAs - here
Additionally you will need a fine-tipped soldering iron, leaded solder (lower temperature solder is essential for assembly of the BatSignal ultrasonic module), tweezers, a small pair of pliers and some fine flush-cutting wire cutters. If you have access to a Mini Hotplate and low-temperature solder paste, that will make assembly of the BatSignal much easier.
Recommended assembly order (assembly time about 30 minutes) :
BEFORE YOU START : check you can re-flash the Pico before you do any soldering, then continue with this list
- Solder Adafruit SD interface board to back side of π•pistrelle baseboard
- Solder Raspberry Pi Pico to π•pistrelle baseboard
- Check SD card interface
- Solder resistors and LEDs associated with spectrum display
- Check LED spectrum display
- Solder ultrasonic support circuitry and headphone sockets
- Solder the headers for the ultrasonic carrier board onto the π•pistrelle baseboard
- Assemble "BatSignal" ultrasonic carrier board
- Check BatSignal and ultrasonic signal path before soldering - it is HARD to remove, make sure it works before you solder it down
- Solder BatSignal to π•pistrelle baseboard
- Re-check BatSignal and ultrasonic signal path
- Solder buttons and rotary controller
- Check buttons and rotary controller
- You should now have a working π•pistrelle scanning bat detector
- Final step - solder battery holder to back side of π•pistrelle baseboard
BEFORE YOU START : check you can re-flash the Pico before you do any soldering, then continue with this list
Solder Adafruit SD interface board to back of π•pistrelle baseboard
Solder balls
Tin the SD interface board on all 6 through-holes, and on the two large connector holes
Stick cardboard onto π•pistrelle baseboard - stands the SD card about 1/2mm away from the π•pistrelle baseboard and makes it much easier to see the quality of solder joints between SD interface and baseboard
Check SD interface is working by inserting a micro SD card and flashing the Pico with checkSD.uf2
Solder balls
Tin the SD interface board on all 6 through-holes, and on the two large connector holes
Stick cardboard onto π•pistrelle baseboard - stands the SD card about 1/2mm away from the π•pistrelle baseboard and makes it much easier to see the quality of solder joints between SD interface and baseboard
Check SD interface is working by inserting a micro SD card and flashing the Pico with checkSD.uf2
2: Solder Raspberry Pi Pico to π•pistrelle baseboard
Check Pico is working by flashing the Pico with checkPico.uf2
3: Solder resistors and LEDs associated with spectrum display
Check all LEDs work by flashing the Pico with checkLEDs.uf2
5: If you have a pre-assembled ultrasonic carrier board, go to 6, otherwise assemble ultrasonic carrier board
THIS IS TRICKY.
6: Solder the headers for the ultrasonic carrier board onto the π•pistrelle baseboard
Long side of the header will connect to the ultrasonic carrier board
7: Test the ultrasonic carrier board - see the video below for a work through of this section
First flash the Pico with pipistrelle.uf2 - this is the full production code for π•pistrelle
Now slide the ultrasonic carrier onto the long legs of the 0.1" pitch headers, but do not solder yet, push the carrier board all the way down the leads
Splay the leads outwards a little using pliers, no more than 1-2mm
Pull the carrier board back up, until friction keeps it held in place
Apply power to the π•pistrelle via USB
If everything is working well, then rubbing your fingers together near the bat should result in activity on the LED spectrum display
8: Solder the ultrasonic carrier board onto the π•pistrelle baseboard
Push the carrier board back down all the way, solder in place, and snip off the excess lead length
Check again by applying power to the π•pistrelle via USB, do the 'finger rub' test
9: Solder the battery holder onto the back surface of the π•pistrelle baseboard
Put 3 AA batteries (rechargeable or alkaline) and do the 'finger rub' test
NEVER CONNECT USB POWER WHILE ALL THRE BATTERIES ARE INSTALLED - to re-flash, remove one battery, re-flash the Pico, then put the third battery back in
10: You now have a π•pistrelle and can go detect and record bats!
Check all LEDs work by flashing the Pico with checkLEDs.uf2
5: If you have a pre-assembled ultrasonic carrier board, go to 6, otherwise assemble ultrasonic carrier board
THIS IS TRICKY.
6: Solder the headers for the ultrasonic carrier board onto the π•pistrelle baseboard
Long side of the header will connect to the ultrasonic carrier board
7: Test the ultrasonic carrier board - see the video below for a work through of this section
First flash the Pico with pipistrelle.uf2 - this is the full production code for π•pistrelle
Now slide the ultrasonic carrier onto the long legs of the 0.1" pitch headers, but do not solder yet, push the carrier board all the way down the leads
Splay the leads outwards a little using pliers, no more than 1-2mm
Pull the carrier board back up, until friction keeps it held in place
Apply power to the π•pistrelle via USB
If everything is working well, then rubbing your fingers together near the bat should result in activity on the LED spectrum display
8: Solder the ultrasonic carrier board onto the π•pistrelle baseboard
Push the carrier board back down all the way, solder in place, and snip off the excess lead length
Check again by applying power to the π•pistrelle via USB, do the 'finger rub' test
9: Solder the battery holder onto the back surface of the π•pistrelle baseboard
Put 3 AA batteries (rechargeable or alkaline) and do the 'finger rub' test
NEVER CONNECT USB POWER WHILE ALL THRE BATTERIES ARE INSTALLED - to re-flash, remove one battery, re-flash the Pico, then put the third battery back in
10: You now have a π•pistrelle and can go detect and record bats!
