Please note that this is a hobby project - I will try my best to provide any support you need, but be patient if it takes me a while to respond
VERSION 2.1
This page contains the bill of materials and assembly instructions for a single π•pistrelle bat detector, version 2.1 with all-SMD devices. Because of the exclusive use of surface-mount technology, both a hotplate (or a hot air gun) and a soldering iron are required for this assembly, the recommended hotplate can be bought from Amazon for under £8 (July 2022 price). A silicone rubber soldering mat is also recommended to protect your work surface against heat damage from the hotplate, and to give the feet of the hotplate some frictional grip - you don not want this thing to accidentally fall into your lap. You will also need some solder paste. I use a Pb63Sn37 mix because the lead keeps the melting point low enough to support a short heat cycle with the hot plate, minimizing the risk of damage to the LEDs. Also, you will need a fine-tipped soldering iron, some leaded solder (as close to Pb63Sn37 as you can find), a pair of flush cutters, and some fine tweezers to position the SMD components on the PCB.
It is recommended that you build 10 detectors at a time to achieve lowest build cost. The minimum order quantity for blank PCBs is 5, so this is a good group activity e.g. for a local bat group. If you are outside the UK, you won't be able to do this unless you intend building a VERY large number of devices - the "BatSignal" ultrasonic microphone / op-amp module is only available to order in 120-off, minimum - each PCB is a panel of 6x4 BatSignals - with a price break at 240. If you don't spend $10 on the π•pistrelle solder stencil you will struggle, but feel free to give it a shot if you fancy your chances with a syringe or a cocktail stick.
Instructions for flashing the Pico and debugging by inspecting Pico's textual output are Mac-specific. You should be able to find instructions for PC on the web - check out the Raspberry Pi website.
All links to external suppliers were good at 11th May 2022
VERSION 2.1
This page contains the bill of materials and assembly instructions for a single π•pistrelle bat detector, version 2.1 with all-SMD devices. Because of the exclusive use of surface-mount technology, both a hotplate (or a hot air gun) and a soldering iron are required for this assembly, the recommended hotplate can be bought from Amazon for under £8 (July 2022 price). A silicone rubber soldering mat is also recommended to protect your work surface against heat damage from the hotplate, and to give the feet of the hotplate some frictional grip - you don not want this thing to accidentally fall into your lap. You will also need some solder paste. I use a Pb63Sn37 mix because the lead keeps the melting point low enough to support a short heat cycle with the hot plate, minimizing the risk of damage to the LEDs. Also, you will need a fine-tipped soldering iron, some leaded solder (as close to Pb63Sn37 as you can find), a pair of flush cutters, and some fine tweezers to position the SMD components on the PCB.
It is recommended that you build 10 detectors at a time to achieve lowest build cost. The minimum order quantity for blank PCBs is 5, so this is a good group activity e.g. for a local bat group. If you are outside the UK, you won't be able to do this unless you intend building a VERY large number of devices - the "BatSignal" ultrasonic microphone / op-amp module is only available to order in 120-off, minimum - each PCB is a panel of 6x4 BatSignals - with a price break at 240. If you don't spend $10 on the π•pistrelle solder stencil you will struggle, but feel free to give it a shot if you fancy your chances with a syringe or a cocktail stick.
Instructions for flashing the Pico and debugging by inspecting Pico's textual output are Mac-specific. You should be able to find instructions for PC on the web - check out the Raspberry Pi website.
All links to external suppliers were good at 11th May 2022
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Bill of materials
1x π•pistrelle v2.1 baseboard printed circuit board available 5-off or 10-off from this page on PCBWay.com - and please do order the SMD solder stencil, it will make your assembly process much easier. In general, to minimize component prices, SHOP AROUND. The same parts can often be found with eBay sellers at a fraction of the prices charged by industrial-scale component suppliers such as Farnell, DigiKey, Mouser and RS.
But at the same time, do try to give money to the little guys like Pi Supply, The Pi Hut and Pimoroni and keep the UK's maker space healthy and vibrant.
Not shown - 1x battery holder, PCB mount, for 3x AA batteries (on back of PCB)
A - 1x Raspberry Pi Pico (not the WiFi version, not the version with header pins - this one)
B - 1x assembled BatSignal plus 2 sets of 5x 0.1" header pins
C - 1x MEM2061-01-188-00-A microSD interface
D - 1x rotary encoder with shaft for 6mm knob (e.g Bourns PEC12R)
E - 2x momentary push button switches 12mm x 12mm (shop around on eBay for these)
F - 2x 3.5mm headphone jack (e.g SJ2-3574A-SMT-TR - shop around for low cost alternatives with the same pinout)
G - 10x LEDs 2.0V - 2.5V 3216 SMD
H - 13x 220Ω resistors 3216 SMD
I - 2x 100kΩ resistors 3216 SMD
J - 1x 47kΩ resistor 3216 SMD
K - 1x 2.2kΩ resistor 3216 SMD
L - 6x 4.7µF MLCC capacitors 3216 SMD
M - 4x 0.1µF MLCC capacitors 3216 SMD
1x π•pistrelle v2.1 baseboard printed circuit board available 5-off or 10-off from this page on PCBWay.com - and please do order the SMD solder stencil, it will make your assembly process much easier. In general, to minimize component prices, SHOP AROUND. The same parts can often be found with eBay sellers at a fraction of the prices charged by industrial-scale component suppliers such as Farnell, DigiKey, Mouser and RS.
But at the same time, do try to give money to the little guys like Pi Supply, The Pi Hut and Pimoroni and keep the UK's maker space healthy and vibrant.
Not shown - 1x battery holder, PCB mount, for 3x AA batteries (on back of PCB)
A - 1x Raspberry Pi Pico (not the WiFi version, not the version with header pins - this one)
B - 1x assembled BatSignal plus 2 sets of 5x 0.1" header pins
C - 1x MEM2061-01-188-00-A microSD interface
D - 1x rotary encoder with shaft for 6mm knob (e.g Bourns PEC12R)
E - 2x momentary push button switches 12mm x 12mm (shop around on eBay for these)
F - 2x 3.5mm headphone jack (e.g SJ2-3574A-SMT-TR - shop around for low cost alternatives with the same pinout)
G - 10x LEDs 2.0V - 2.5V 3216 SMD
H - 13x 220Ω resistors 3216 SMD
I - 2x 100kΩ resistors 3216 SMD
J - 1x 47kΩ resistor 3216 SMD
K - 1x 2.2kΩ resistor 3216 SMD
L - 6x 4.7µF MLCC capacitors 3216 SMD
M - 4x 0.1µF MLCC capacitors 3216 SMD
Videos : assembling the BatSignal module using a hotplate
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Assembling the BatSignal requires a bare BatSignal PCB (right), a MicroChip MCP622 E/S op-amp and a Knowles SiSonic SPU0410LR5H-QB ultrasonic MEMS analog microphone.
Two sets of 0.1" pitch headers pins with 5 pins each are needed to attach the BatSignal to the π•pistrelle PCB. Later revisions of the hardware may eliminate the requirement for headers. The process of assembling a BatSignal is really easy if you have a solder paste stencil for the BatSignal and want to make a large number at a time. Otherwise, to make small numbers of individual BatSignals, it is actually better to use leaded solder rather than paste - controlling the amount of paste on the PCB is pretty much impossible without a stencil, and too much paste risks solder and / or flux getting into the port of the microphone and destroying the device. Even with a stencil I have found it more reliable to solder only the op amp on the hotplate, allowing the solder paste on the microphone leads to melt. If the solder on the microphone footprint fills the hole, use a solder sucker to get it out, then reflow the board with the microphone in place. |
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Use the link on the left to order 5 or 10 π•pistrelle blank PCBs directly from PCBWay.com The BatSignal project (to allow you to order 120 or 240 BatSignals plus a SMD solder paste stencil) will be made avaliable soon. |
