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 😀👍
This page contains the bill of materials and assembly instructions for a single π•pistrelle bat detector. And it's a work in progress - please keep checking back (Most recent update 09.28 May 15th 2022).
It is recommended that you build 10 detectors at a time to achieve lowest build cost, and 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 150-off, minimum, with a price break at 300.
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
Bill of materials
1x π•pistrelle v1.6MC baseboard printed circuit board available 5-off or 10-off from this page on PCBWay.com
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.
This page contains the bill of materials and assembly instructions for a single π•pistrelle bat detector. And it's a work in progress - please keep checking back (Most recent update 09.28 May 15th 2022).
It is recommended that you build 10 detectors at a time to achieve lowest build cost, and 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 150-off, minimum, with a price break at 300.
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
Bill of materials
1x π•pistrelle v1.6MC baseboard printed circuit board available 5-off or 10-off from this page on PCBWay.com
- allow at least 10 days for manufacture and delivery, late 2021 pricing approx £16.50 for 10 incl FedEx delivery from China
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.
|
A - 1x D-knob suitable for 6mm shaft B - 1x endless rotary encoder C - 2x 12mmx12mm momentary pushbutton D*, O - 4x 1uF capacitor for decoupling of voltage regulators E*, P - 2x MicroChip TC1108 330mA 3.3v LDO voltage regulator F - 10x 2.2V LEDs, 3mm pitch G - 10x 220ohm resistors I - 1x 22uF capacitor (op amp supply) J - 1x 100nF capacitor (op amp filter circuit - high pass) K - 1x 56k resistor - op amp feedback L - 1x 220 ohm resistor - op amp input M- 1x BatSignal ultrasonic microphone / op amp module - contact me for details N - 2x 100k resistor (op amp supply circuit - split / bias) Q - 1x 3.5mm headphone socket R - 1x 100nF capacitor (PWM audio - low pass filter) S - 1x 22uF capacitor (PWM audio - AC coupling / high pass filter) T - 1x 1k resistor (PWM audio - low pass filter) U - 1x 100 ohm resistor (PWM audio - line level compensation / low-pass filter) V - 1x 220 ohm resistor (PWM audio - line level compensation) W - 1x Raspberry Pi Pico X - (on backside) - 1x 3 AA battery holder PCB mount Y* - (on backside) - 1x AdaFruit SD / SPI breakout board *may be omitted for a detector-only confiiguration i.e no audio recording Note on the capacitors used in this design. Every device illustrated here is a through-hole capacitor. Note that these can be substituted with 3.2mm surface-mount MLCC parts, which leads to a much tidier and cheaper device with quicker assembly. These MLCC parts are quite easy to solder, require no cutting of leads, and can be soldered to the through-hole pads on the PCB. |
|
SUMMARY
1x π•pistrelle v1.6MC (pinout for MicroChip TC1108 LDO regulator) 1x BatSignal module 1x Raspberry Pi Pico 2x MicroChip TC1108 3.3V LDO voltage regulator 10x LED 3mm 2.2V 3mm 12x 220ohm resistor 2x 100k resistor 1x 56k resistor 1x 1k resistor 1x 100ohm resistor 3x 22uF electrolytic 2x 100nF electrolytic 2x 1uF electrolytic 2x momentary pushbuttons 1x rotary encoder 1x 3.5mm headphone adapter 1x 3AA battery holder 1x AdaFruit SD / SPI breakout Additionally you will need a fine-tipped soldering iron, leaded solder (lower temperature solder is essential for reliable assembly of the BatSignal ultrasonic module), tweezers, a small pair of pliers and some fine flush-cutting wire cutters. A Mini Hotplate or similar is requird to assemble the BatSignal. Software : pipistrelle.uf2 - complete Bat Detector software including overnight recorder facility |
Version 1.6 mockup with MLCC capacitors - a much tidier solution than using through-hole devices
|
WARNING : there is a design error on versions 1.5 and 1.6 that requires a wire
There is a design error in versions 1.5 and 1.6 of the PCB, which can be fixed by shorting two of the pins on the headphone jack. This error stops 4-pole headphone connectors - e.g Apple earbuds - from working. 3-pole connectors - for example stereo cables to connect to an external speaker or an AUX input, or higher-quality headphones - seem to work fine, but it is better to fix this problem upfront than to try to patch it later.
The easiest fix is to use part of the lead from an electrolytic capacitor which will be used later assembling the device. These leads are thin enough to fit through the small vias incorporated into the headphone connector solder pads.
Cut about an inch off the long lead of the capacitor, bend it to shape, and pass it through the small vias on the backside of the PCB, as shown in the photograph. The left half of the pictures shows the back side of the PCB, the right half the front side. Bend the ends of the wire that stick through to the front side of the PCB as shown here, away from rather than towards the body of the headphone jack. This puts them well out of the way of the headphone jack's leads, so the jack will sit flat and flush on the PCB. Now when you solder the headphone jack in place the two pins will be shorted.
With that sorted, actual assembly can begin.
The easiest fix is to use part of the lead from an electrolytic capacitor which will be used later assembling the device. These leads are thin enough to fit through the small vias incorporated into the headphone connector solder pads.
Cut about an inch off the long lead of the capacitor, bend it to shape, and pass it through the small vias on the backside of the PCB, as shown in the photograph. The left half of the pictures shows the back side of the PCB, the right half the front side. Bend the ends of the wire that stick through to the front side of the PCB as shown here, away from rather than towards the body of the headphone jack. This puts them well out of the way of the headphone jack's leads, so the jack will sit flat and flush on the PCB. Now when you solder the headphone jack in place the two pins will be shorted.
With that sorted, actual assembly can begin.
Videos : mounting the AdaFruit SD interface to π•pistrelle using leaded solder
It can be tricky to get the SMD pad on the π•pistrelle PCB to make a good solder connection to the through-hole pad on the SD interface, this video shows the way that works best for me. There are two tricks to a successful mount :
1) get some separation between the two PCBs so that solder can bridge the gap and form a secure electrical connection. Masking tape folded over to be sticky on both sides works well, and also holds the AdaFruit in place as you solder it to the π•pistrelle.
2) put the 0.1" headers through the holes before you try applying an iron and solder. Heat will be transferred down to the π•pistrelle SMD pad, and the header pin will wick solder down to the pad.
Take a look - it's less than 5 minutes of your time and will potentially save you hours of grief.
It isn't recommended to try this using low-temperature solder paste smeared onto the SMD pads - I've tried it and it worked out badly, messy and sticky, and still had both dry joints and shorts, so I recommend sticking to a soldering iron and the header pins.
1) get some separation between the two PCBs so that solder can bridge the gap and form a secure electrical connection. Masking tape folded over to be sticky on both sides works well, and also holds the AdaFruit in place as you solder it to the π•pistrelle.
2) put the 0.1" headers through the holes before you try applying an iron and solder. Heat will be transferred down to the π•pistrelle SMD pad, and the header pin will wick solder down to the pad.
Take a look - it's less than 5 minutes of your time and will potentially save you hours of grief.
It isn't recommended to try this using low-temperature solder paste smeared onto the SMD pads - I've tried it and it worked out badly, messy and sticky, and still had both dry joints and shorts, so I recommend sticking to a soldering iron and the header pins.
Videos : assembling the BatSignal module using a mini hotplate
|
This 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.
The easiest process is to pre-tin the leads with an iron and leaded solder, then reflow the BatSignal using a mini hotplate. |
|
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
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 - see video above
- Solder Raspberry Pi Pico to π•pistrelle baseboard
- Solder resistors and LEDs associated with spectrum display
- Check LED spectrum display by flashing Pico
- Solder ultrasonic and audio output support circuitry and headphone socket
- Solder buttons and rotary controller
- Check buttons, rotary controller and audio ouput by flashing Pico and playing with rotary and left button
- Solder the headers for the BatSignal ultrasonic carrier board onto the π•pistrelle baseboard
- Assemble BatSignal ultrasonic carrier board
- Check BatSignal and ultrasonic signal path before soldering - it is VERY 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
- You should now have a working π•pistrelle scanning bat detector
- Insert a formatted, fast micro SD card into the AdaFruit and check 'single file record' and multi-file record - you will need a smartphone and the AudioMoth app to use recordign functionality
- Final step - solder battery holder to back side of π•pistrelle baseboard
|
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 150 or 300 BatSignals plus a SMD solder paste stencil) will be made avaliable soon. |
