Title slide

v 0.90

5^th July 2026

All designed by ...

Phil Atkin

• A retired “ex Technology guy”
• From Malmsbury in Wiltshire
• He is constantly evolving designs and software, so we may find new stuff today (we all like surprises!)
• Listen to Phil talking about his detectors on BCT’s podcast Batchat. S6Ep58
• Web: https://www.pippyg.com

​

A family of Bat detectors...

Griff mini (£8) & Griff (£11)

384kHz USB microphones

• Connects via cable to app on mobile device (or desktop). The two apps are very different:
• Partner iOS app. Search “Bat Detector” in Apple app. Store
• Autoscan heterodyne & time-expanding detector and recorder
• Android app. Search “Batgizzmo” in Google Play store
• Maunal dual Heterodyne detector and recorder

Pipistrelle Mini (£16) & Nano (£14)

Handheld bat detectors

• Can be used as USB Mic (i.e. all Griff features) …PLUS …
• Autoscan heterodyne & time-expanding detector
• Spoken peak frequency & LED spectrum display (on Mini)
• Sound to headphones or speaker via 3.5mm cable

PippyG (£20)– Static/passive (overnight) recorder

• Configured by pipistrelle app (iOS & Android)

​

Note: all mics need a specific OTG connector cable (£2+)

​

Build �Process

• Order components and boards (PCBs)
• Prepare PCBs – Remove formers, mic hole
• Prepare stencil framework
• Flash Picos with Firmware
• Build and Safety
• Apply solder paste to PCBs with stencil (5min)
• Place components (20min)
• Melt solder on hotplate (10min)
• Cool then Test (10min)
• Troubleshoot faults & fix (???)
• Attach back cover & solder battery case (10m)
• Insert batteries and plug in headphones, or connect to phone, and go listen to bats!

Todays Build

• This is not complicated, but it is fiddly
• You will need patience, steady hands and good near vision
• The surface-mount components are very small, and need to be placed precisely onto the solder paste
• Take your time, double check everything
• Remember to breath!
• Enjoy the process ☺

​

Any questions just ask!

1. Build/Safety
• Todays Build
• Safety
• Practice placement
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

Safety

Hazards :

• Hotplate : 260°C
• PCBs fresh off the hotplate : 250+°C
• Soldering iron tip : 400°C
• Hot glue gun : 200°C
• Toxic material : solder paste and flux - wash your hands before eating
• Cutting risk : flush cutters are SHARP, wear (safety) glasses

​

PLEASE BE EXTRA CAREFUL TODAY

1. Build/Safety
• Todays Build
• Safety
• Practice placement
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

Components - Placement

• When using tweezers keep your hand in a natural position. Turn the board or mat if needed
• Ensure the heal of your hand is firmly grounded
• Align the component with the board before picking up, ideally resistor values the same way
• Pick up capacitors and resistors across the width
• Check the value and alignment of the text on the board, this (mostly) shows the orientation and component. If in doubt, follow the paper diagram.
• Pay particular attention to component orientation when 2 identically-valued components are next to each other
• Remember some only fit one way (polarity)

Don’t knock components already placed!

1. Build/Safety
• Todays Build
• Safety
• Practice placement
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

​

Solder Paste

• We are using non lead solder* but this has a high melting point; 232°C *Sn96.5%, Ag3%, Cu0.5%
• Carefully check the alignment of the stencil
• Solder paste is sticky and horrible - if you have long hair, PLEASE tie it back
• Apply solder paste with spreaders using firm but not hard pressure
• Check all silver pads are covered before lifting stencil
• Use magnifier to check no solder paste is connecting between pads (esp. Mic, Op. Amp & mSD)
• Clean paste from Mic hole if required
• Wash hands if you have any solder paste on them

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

Components - Order

We will be placing in the following order:

• Raspberry Pi Pico
• - mSD holder
• - Switch
• - 3.5mm Jack
• Microphone
• IC Op. Amp
• Capacitors
• Resistors
• - Ferrite Bead
• - LEDs

1. Build/Safety
2. Solder paste
3. Components
• Mini Griff
• Griff
• Mini Pipistrelle
• PippyG
• π•Pistrelle
• BatSynth
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

Mini Griff mic – 24Aug25

Raspberry Pi Pico x 1

38mm Brooch Pin

Ford-2 Microphone x 1

IC OpAmp GP 1 SOT23-5 x 1 (note pin 1)

​

Capacitors (5)

• 0.1uF Ceramic x 3
• 47uF Ceramic x 2

​

Resistors (5)

• 47k ohm x 3
• 470 ohm x 1
• 100 ohm x 1

​

14 components in total

Griff – 20^thOct25

Raspberry Pi Pico x 1

38mm Brooch Pin (Option)

Ford-2 Microphone x 1

IC OpAmp GP 1 x 1 (note pin 1)

​

Capacitors (5)

• 0.1uF Ceramic x 3
• 47uF Ceramic x 2

​

Resistors (5)

• 47k ohm x 3
• 470 ohm x 1
• 100 ohm x 1

​

Back Cover (Option)

14 components in total

Nano PiPistrelle – 8Jun26

Raspberry Pi Pico x 1

Switch slide x 1

Audio jack, 3.5 mm x 1

Mic mems analog Syntiant (Ford) x 1

IC opamp gp 1 x 1 (note pin 1 dot)

Capacitors (7)

• 0.1uF Ceramic x 3
• 22uF Ceramic x 3

Resistors (21)

• 47k ohm x 5
• Ferrite 500 ohm x 1
• 220 ohm x 2
• 100 ohm x 1
• 470 ohm x 2

​

LED x 1 (note polarity!)

Back cover

Battery holder AAA 3 cell pin

23 components in total

Mini PiPistrelle – 14Feb’26

Raspberry Pi Pico x 1

Switch slide x 1

Audio jack, 3.5 mm x 1

IC opamp gp 1 x 1 (note pin 1 dot)

Mic mems analog Syntiant (Ford) x 1

Capacitors (7)

• 0.1uF Ceramic x 4
• 22uF Ceramic x 3

Resistors (21)

• 47k ohm x 5
• Ferrite 500 ohm x 1
• 220 ohm x 4
• 470 ohm x 11

​

LED x 10 (note polarity!)

Back cover

Battery holder AAA 3 cell pin

43 components in total

LED Colour options

We have Red, Orange, Yellow, Green and Blue – in ANY combination you like … ideas …

PippyG v 4.04 (2/5/25)

Raspberry Pi Pico x 1

Push/Pull Micro SD card holder x1

Switch slide x 1

IC opamp gp 1 x 1 (note pin 1 dot)

Mic mems analog Syntiant (Ford) x 1

Capacitors (7)

• 47 uF tant/poly x 2
• 0.1uF Ceramic x 3
• 22uF Ceramic x 2

Resistors (21)

• 47k ohm x 3
• Ferrite 500 ohm x 2
• 470 ohm x 2

​

LED x 1 (note polarity!)

Back cover

Battery holder AA 3 cell pin

20 components in total

Bat Synth – v0.2 - April’25

Raspberry Pi Pico x 1

Power Amp module LTK5128

Capacitors

• 47 uF tant/poly x 3 (note polarity)
• 0.1uF C0G/NP0 x 1
• 1 nF Ceramic x 3

Resistors

• 47k ohm x 3
• 220 ohm x 18
• 3.3k ohm x 1
• Ferrite Bead 500 ohm x1

LED x 10 (note polarity)

Speaker 3.72 Ohm 100W

Screws, self tap x 3

Back cover

1p Coin x 6

Hotplate

• It gets hot! 250+ °C
• Do not touch silver plate or top edge
• Keep long sleeves & hair away from hot plate
• Flux fumes start at ~120°C
• Ensure filtered extractor is on
• Keep head away from fumes
• Watch for grey solder paste turning silver
• May need to hold down edges of board lightly with tweezers, DO NOT turn it
• Use care and old boards to remove from plate
• Only place next boards on hotplate when cool (<150°C)

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery

Basic Mic Test – Pips & Griff

Once the board is cool it can be tested.

• Plug the Pico mUSB into a USB power bank.
• The switch is bypassed on mUSB power so no need to switch on
• The green Pico LED should flash 5 times
• Rub fingers in front of mic to produce ultrasound
• Does the Pico LED flicker in response to the noise? respond?

​

If Yes, its looking good!

The Mic is connected.

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting mini Pipistrelle
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

Testing Griff functions (iOS)

Download the Partner iOS app. Search “Bat Detector” in Apple app. store

Open iPhone App and in settings configure:

• “Force output to device speaker” to ON
• “Hetrodyne volume” to Max
• “RTTX volume” to Max (Real Time, Time Expansion)

In the App, click on the screen to bring up bottom buttons:

• Click the “Mic Button” to turn on mic, & turn off demo mode
• Click “Heterodyne” or “Time Expansion” Button to turn on sound.

Click here for the manual for the Bat Detector App

Connect to mic via OTG (Camera) connector and cable. Play ultrasound and check:

• Series of calls scrolling across spectrogram display.
• Hetrodyne and Time Expansion modes produce the right type of noise
• Hit record, and check 5 sec recordings are stored on device

If yes to all, your detector works as a mic!

​

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Testing Griff functions (Android)

Download the Android app. (in development). Search “Batgizzmo” in Google Play store

Connect Android devices to mic via OTG cable.

Open App and click the Microphone button:

• Click OK to allow BatGizmo to access the Mic

Click Speaker button to access Audio Settings:

• Select “Dual Hetrodyne mode”, starting recommendations:
• Reference = 45kHz
• Reference 2 = 25kHz

Play ultrasound & check:

• Series of calls scrolling across spectrogram display.
• Move the hand to tune the Heterodyne frequency, to achieve the lowest (in tone) sounds from the device
• Hit record, and check 5 sec recordings are stored on device

If yes to all, your detector works as a mic!

​

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Testing Pipistrelles – mini & nano

Plug in speaker, or headphone, to 3.5mm jack

While plugging a USB power bank into Pico mUSB:

• Press and hold both left and right buttons
• All Ten LED should flash 4 times
• Rub fingers in front of mic to produce ultrasound
• LEDs flicker in response to the noise
• Do you hear Hetrodyne type sounds?
• Press left button
• Is Frequency announced?
• Press right button (Annouce= “Time Expansion”). Make ultrasound
• All LED flash
• Do you hear single Time expanded sound?
• Press right button again (Annouce= “Heterodyne”). Make ultrasound
• All LED flash
• Do you hear Heterodyne type sounds again?
• “Attach” a battery pack and check ON switch works

If yes to all, your detector works as a mini!

​

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Starting Pipistrelles

On 29^th April 2026 Phil made changes so on startup all DIY Pipistrelles now:

• When started on battery power, they act as Pipistrelle in standard (Batwalk) mode @ Vol. 5
• When started from mUSB power via Pico (without batteries) they act as a USB microphone

Other startup options, when buttons are touched :

• With both buttons touched:
• Power on over mUSB: Standard (Batwalk) mode @ volume 5
• Power on from battery: Advanced mode (see next slide) @ volume 5
• With one button touched, with Power from battery OR over mUSB:
• Left button on : Standard (BatWalk) mode @ volume 2
• Right button on : Standard (BatWalk)mode @ volume 8

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Pipistrelles Batwalk mode

With firmware later than 29/4/26 , the new simplified standard (BatWalk) user interface is:

• Single Press:
• Left button – Speak last peak frequency
• Right button – Toggle mode between Time Expansion and Heterodyne. The current mode is announced.
• Press and hold:
• Left button – Volume down. The current volume level is announced, and shown on the LEDs, from 1 (low) to 10 (high)
• Right button – Volume up. The current volume level is announced, and shown on the LEDs

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Pipistrelles Advanced mode

With firmware earlier than 29/4/26 , or if booted into advanced mode:

• Left button:
• Single : speak current frequency
• Long : enter time expansion mode
• Triple : volume down
• Double : lower freeze frequency
• If time expanding : no effect
• If scanning : freeze scanning
• If frozen : lower frequency
• Right button
• Single : toggle scanning / freeze heterodyne frequency
• Long : enter heterodyne mode
• Triple : volume up
• Double : raise freeze frequency
• If time expanding : no effect
• If scanning : freeze scanning
• If frozen : raise frequency

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting Pipistrelles
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Testing PippyG functions

Connect mUSB power, no mSD

• Pico is always on.

Connect mUSB power With mSD

• Pico LED on, onboard LED flash fast 9? times, then responds to Mic

Power off, check mSD card empty, then insert. Open Pipistrelle app, set time to SLEEP & pick a device #ID. Play chirp from App at 2/3 rds volume

• Onboard LED flash flash fast 7? times (if once, try chirp again)
• Then Pico LED flash every 5 sec, and LED not responding to noise

Power off, remove mSD and look at contents

• folder created = bats_dev###, subfolder created = year_date_mnt_??

In subfolder:

• chirp.txt & Latlong_**.******_**.******_.html. Then clear mSD card

Set time to AWAKE, +1 to device #ID. Play chirp from App at 2/3 rds volume

• Onboard LED flash fast 7? times (if once, try chirp again)
• Pico LED flashes respond to noise

Make ultrasound noise

• Pico LED on for duration of sound.

Power off, remove mSD and look at contents

• folder created = bats_dev###, subfolder created = year_date_mnt_??

In subfolder:

• chirp.txt & Latlong_**.******_**.******_.html
• Recordings: Dev_***_date_time.wav

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
• Basic Mic Test – Pips & Griff
• Testing Griff functions (iOS)
• Testing Griff (Android)
• Testing Pipistrelles
• Starting mini Pipistrelle
• Testing π•pistrelle
• Testing PippyG functions
6. Troubleshoot
7. Cover & battery

​

Mic not working 1/2

Symptom : microphone does not work - no LED response to fingers rubbed near microphone

• Possible problems:
• Microphone has a “dry joint”,
• The mic solder pads are cross connected,
• Solder is blocking the microphone hole
• The microphone isn’t aligned with the hole
• Power not connected to Amp/Mic
• Check: Mic is aligned and hole not blocked, then:
• Check resistance between Mic casing (ring pad) and Ground (Pico pin 3) Should be connected
• Check resistance between the ends on the two 0.1uF capacitors either side of Mic. Should be 120-180Kohm.
• If above are OK: Power on device and check voltage on OpAmp.
• Some should be 3.4v. If not, suspect Pico pads 35-40 not connected.

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
1. Mic not working
2. Some LEDs not working
• Pico Connections
3. mSD not working
4. Anything else
7. Cover & battery

Mic not working – 2/2

If mic is not connected on previous two tests:

• Worth Trying: back onto the hotplate, to see if re-melting helps
• We could try removing the mic and checking for solder in hole on PCB, and on microphone, then realigning. But I have had limited success with this.
• Solution: discard the device. I may have a tested and working device you can take home with you.
• I will recycle as many components as possible, and reuse on a device for the bat group

​

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
1. Mic not working
2. Some LEDs not working
• Pico Connections
3. mSD not working
4. Anything else
7. Cover & battery

Some LEDs not working

Symptom : some LEDs do not work

• Likely problem : dry joints at the LED, the LED’s resistor, or the Pico GPIO pin.
• Typically the Pico side, or the LED joint at the edge of the board, is the problem.
• Solution : run a soldering iron over the joints connecting the Pico to the LED and re-test
• Lookup the relevant Pico pin numbers on following slide

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
1. Mic not working
2. Some LEDs not working
• Pico Connections
3. mSD not working
4. Anything else
7. Cover & battery

Pico connections

mSD not Working

Symptom: the SD card does not work / is not recognised

• Likely problem: dry joints at the SD interface, or the GPIO pins on the Pico that connect to the SD interface
• Solution: run a soldering iron over the relevant joints connecting the Pico to the SD interface and re-test. See Pico connections on previous slide
• If necessary, replace the micro-SD socket.

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
1. Mic not working
2. Some LEDs not working
• Pico Connections
3. mSD not working
4. Anything else
7. Cover & battery

Anything else not working

Symptom: anything else wrong

• Likely problem: dry joints somewhere, a bad PCB or a bad component
• Solution: discard the device. I may have a tested and working device you can take home with you.
• I will reclaim as many valuable components as possible (i.e op-amp, Pico, SD interface) and reuse on a device for the bat group

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
1. Mic not working
2. Some LEDs not working
• Pico Connections
3. mSD not working
4. Anything else
7. Cover & battery

Cover and battery

• For those that use batteries, attach battery holder to cover using double sided sticky foam.
• For devices that use hot glue:
• Using hot glue gun add blobs of glue to each of the pads on the inside of the cover. Allow to cool and remove excess.
• Put board on hotplate and heat to 100°C
• Take board off hotplate using gloves and firmly press into cover to melt hot glue, aligning battery holder pins through holes. Hold ‘til cool
• Use wire snips to cut pins. Wear (safety) glasses
• Carefully use Soldering Iron to solder battery holder pins

​

​

1. Build/Safety
2. Solder paste
3. Components
4. Hotplate
5. Cool & Test
6. Troubleshoot
7. Cover & battery