Circuit boards

Andrews & Arnold Ltd make use of a lot of open source software. As a way of giving back to the community we also publish a lot of open source software, and also PCB designs which have been created by us. We plan to stock some of the more popular designs and make available to order, so please let us know if you are interested in purchasing any of these boards.

Please don't hassle to normal sales team, for more information contact We recommend you email before ordering unless you know exactly what you are planning to do with the boards.

These PCBs all made in China for Andrews & Arnold Ltd, and use the director's personal trademark / brand AJK®.

IMPORTANT: These are sold as components only

These are sold as assembled printed circuit boards, much as if you were ordering boards from a PCB manufacturer, and as such are not a complete product. They typically come in a PCB biscuit with blank panels you have to snap off (they are V cut, so snap off easily). You can use them as you wish, and they are ideal for a hobbyist or making prototypes, but if you were to use them to make a product that you put on the market you are responsible for ensuring EMC and regulatory compliance for your product as a whole. They do not come with a case or housing, so please ensure you observe ESD precautions to avoid damage (which may not immediately be apparent). Just to be clear, if popular, we may decide to make some of these a "product" in the future, with certification for CE/UKCA marking, but these are current only sold as components - assembled circuit boards.

Most boards have open source software available on the GitHub links shown. This is normally pre-loaded for your convenience, and then allows over the air updates over WiFi. Note that any software pre-loaded is just for your convenience and not part of what you are buying - it is open source software issued on a GPL licence which is "AS IS" with no warranty. However, GitHub has links for raising any issues or feature requests.

You can also make your own software for these boards. You will need a suitable lead to program them - many have USB-C so a simple USB-C lead will do, but some will need a serial lead such as the tasmotizer board (see below). Those with USB are wired to use RST and DTR to work with esptool seamlessly. You will need a suitable development environment. These modules are based on the ESP32 processor, so the ESP IDF development environment is recommended (though there is also an Arduino based IDE).

For most boards a 3D printable case design is also included on the GitHub link.

The boards all have a date code, and the GitHub project may have moved on since the boards were made. If you have any problems it is worth checking out the project from the corresponding date. This is particularly important for the 3D printed cases based on the PCB design as other date codes may not fit.

Most boards make use of Molex mini SPOX connectors - plugs and leads are not included. We are however looking at Phœnix Contact connectors (albeit more expensive) as they have push in wire plugs. So some products may be shipped with these, so avoiding need for a crimp tool. Most things could use 0.1" square pin headers instead if you are prepared to do some soldering.

If you are interested in a board that has an "order" link - you can just order it. Some are listed on Amazon, and include a link. But if not, or you have any other questions, please contact We're happy to consider having some more made if there is interest. Recent post COVID component shortages have meant that some parts are hard to come by, or expensive, so we may not be able to immediately provide boards, but we welcome your interest. And if you need similar boards designed, do get in touch. We can usually get batches of boards within 2 weeks if needed.

Shipping outside the UK

We do not ship these outside the UK at present - the hoops needed to handle this are not something we are keen to take on at this point. However, we have had reports from customers that a forwarding service like forward2me may be suitable for shipping outside the UK, and apparently works with Amazon. We don't have direct experience of them, and so are not recommending or endorsing them as such, but if you want these sent to a non UK destination such a forwarding company may be the answer. I have no idea how they handle the export issues, but if we are shipping to a UK address, it is not our problem, thankfully.

Simple PCBs

PCBs that do not have a processor, and so no software.

Tasmotizer PCB


This board is a simple serial programming / debug board, but with a number of key features that make it more useful than your average serial lead.

£18.00 Order now: Order 1 module 5060634238014

Also on Amazon

IMPORTANT: You need a USB-C lead to use this

  • Includes a 3.3V regulator to properly power the device you are working on, with enough power for a typical ESP32 based device. A lot of serial leads simply pass on the 5V from USB, which is not good for 3.3V boards and devices.
  • Includes ESD protection diodes to reduce risk of damage when being handled, but please use ESD precautions anyway.
  • Includes RTS (reset), and DTR (GPIO0), controls compatible with the tasmotizer web flashing tool and ESP IDF esptool.
  • Has a 1/10" pin header which can work with 5 pin pads on many of the PCB designs here, essential for those that do not have a USB connection themselves.
  • Has a 1/20" pin header. These headers are directly compatible with the Shelly series of devices allowing them to be flashed with tasmota, or your own software. See YouTube for more.
  • The 1/10" header does not have a RST pin, so switches the power to the device for RST. The 1/20" header has a RST pin which is used.
  • Has a serial activity LED.

There are Shelly products with 5 pin (1/10" spaced) and 7 pin (1/20" spaced) headers that use ESP8266 or ESP32 processors which will work with this board, including original Shelly 1, Shelly Dimmer, and most Shelly Plus models. Re-flashing a Shelly device is something you do at your own risk, obviously.

GitHub YouTube

Tasmotizer in use on a Shelly Plus 1

Solar System

The Solar System is a set of boards that can be used to make up a door entry and/or alarm system.

All of these boards are designed to be powered from 12V DC, and would typically be supplied from an alarm system battery backup box (which is usually more like 13V or 14V).

In addition to these boards, some more general purpose boards can be used for inputs and outputs, but in practice it is simpler and cheaper to use a Shelly Plus 1 for one input and one relay output from 12V. The Shelly Plus i4 DC provides a 4 input 12V powered module as well. These make a good complement to the alarm system devices when loaded with the alarm system software (single CPU version). The Shelly Plus 1 can also run from mains, so handy if you want lights controlled from alarm armed state.

A management system is run by us if required, which provides web based config, status, logging and management of fobs for the system as a whole. However the system is designed to work well during short Internet access failures and even allow access with total WiFi failures. We can also print DESFire ID/access cards and pre-load these on to the management system. Please do ask for details. We don't currently charge for this system (and you could, instead, run your own from the open source project on GitHub), but we may do in the future - we would expect early adopters to continue to have free access.

IMPORTANT: If using the supplied software, you will need a management server of some sort, or use the one we provide, so please ask before ordering parts for this system.



Door controller

The door controller is a small 50mm x 26.5mm circuit board that is designed to be installed on the inside of a door. It fits well inside a typical exit or break glass box. It could also be fitted inside a wooden door by cutting a slot in the edge and covering with a plate and running 12V through the door and a hinge loop.

£36.00 Order now Access2 (single relay): Order 1 module 5060634238021

£48.00 Order now Access3 (larger, dual relay): Order 1 module 5060634238076

  • It can connect to a mag lock, or electric lock (Abloy locks work well). It has a solid state relay so can be used with a separate power supply for the lock, or linked to use the board 12V supply.
  • It can connect to the PN532 NFC reader (see below) for access control from the outside of the door using DESFire EV fobs/cards. The reader supply (5V) is a separate regulator to avoid short circuit on the PN532 board resetting the controller.
  • It has 6 GPIO pins which can use used for various purposes, typically a door closed reed contact, an exit button, a lock engaged contact. Some locks have additional signals such as inside handle used, or keyed lock used. The alarm system code allows all inputs and outputs to be configured as needed.
  • It includes a tamper switch to detect if any case is opened.
  • The Access3 version is slightly larger and has a second solid state relay output (so an extra 3 pin connector)


PN532 HSU NFC Reader

This is designed to work with the door controller, fitting outside the door. It can however be used for any NFC application. The PN532 chip is very flexible.

£24.00 Order now: Order 1 module 5060634238038

  • Simple header fits to a standard 2.54mm header or to a 2.5mm mini SPOX plug which would typically push back in to the hole in a door or wall, making this a very low profile reader (see image below).
  • Connects via a lead (not supplied) to the 4 pin socket on the door controller. It has GND, 3V3/5V, 3.3V Tx, and 3.3V Rx pins for High Speed UART (HSU) operation.
  • A 5th pin can be removed if not needed, or can be used as an input, typically as an adjacent door bell push (connected to GND).
  • A tamper switch is included to detect if any case is removed.
  • The front is flat with no components apart from three recessed LEDs for Red/Amber/Green status.
  • In addition to the alarm system code, PN532 library code for DESFire operation is provided on the GitHub pages. This means you can use this with your own projects instead of the Solar System door controller board.


PN532 NFC Reader on a door

Keypad2: Galaxy Keypad controller

Galaxy keypad controller

This tiny board is designed to actually fit in the void inside a Honeywell Galaxy alarm system keypad/display case (see image below).

£24.00 Order now: Order 1 module 5060634238052

  • A 4 pin connector needs to be wired (soldered) to the 4 pins on the back of the galaxy circuit board.
  • The galaxy then only needs -/+ 12V power and not the normal A/B bus. The operation of the keypad/display is then controlled completely by this board and connected to the rest of the system over WiFi.
  • Note that this does not have a USB connection for programming / debug, but has 5 pads for programming using a Tasmotizer board (see above).
Galaxy keypad controller in situ


Output module

This board provides 10 separate outputs, each of which can be switched to GND or to the supply voltage as needed. This is a good general purpose board for the alarm system as well as other applications.

£48.00 Order now: Order 1 module 5060634238083



Bell box controller

This board is designed to fit in to a typical Pyronix alarm bell box.

  • Two pin power input (12V alarm system power).
  • Eight pin connector to the bell box has:-
  • Inputs for FAULT and TAMPER.
  • Two pin 12V power feed through to the bell box.
  • Can be connected to a GPS receiver board which sets the system clock when no internet connection.


GPS module for Bell Box board

Plug in board for the Bell box to provide time reference for the system from GPS.

Air conditioning


Faikin WiFi module

This is a small PCB that can replace many of the Daikin WiFi modules.

Order Amazon 5060634238052

IMPORTANT: You need a lead for this - it can directly replace the BRP069B41 or BRP069C41 Daikin modules using the lead they use.

  • Unlike the current standard Daikin WiFi module, this is not in any way "cloud based", works on local WiFi with no need for Internet access.
  • The open source software is simple to set up - providing an access point initially to allow WiFi config via a web page.
  • It provides a local web interface to control the air-conditioning unit and show status interactively.
  • It provides MQTT control and status reporting. Home Assistant discover and integration included.
  • It works with older S21 interface, and newer X50 serial interface found on ducted units. It automatically works out which.
  • It can also work (via MQTT) with an environmental monitor (see below) allowing room temperature control with reference to an external temperature sensor - e.g. one that you put by a bed, or more appropriate place in a room than on the air conditioning unit itself. But now also works with BlueCoinT remote BLE temperature sensors directly.
  • Note that this does not have a USB interface so re-programming/debug would need a tasmotizer board. Shipped with the Faikin code which allows over the air updates.
  • Very small (see picture below for comparison with standard Daikin WiFi module).
  • Includes an RGB LED which usually just shows status (red=heat, blue=cool).
  • Includes some support of older Daikin WiFi module local URLs


Size comparison


Environmental Monitor

An environmental monitor for CO₂, humidity, and temperature. This board is available in several configurations.

£30.00 Order now: Order 1 module 5060634238045

IMPORTANT: This needs some work - to get temperature you need a DS18B20 and 3 pin SPOX plug, or fitting an SCD41 (surface mount). For CO2/humidity you need an SCD41. If you want a display, you need to fit one. This is much more of a hobbyist item at present but we are considering selling complete built up modules if they are popular.

  • Can be powered from USB-C lead or 12V DC via a 2 pin socket.
  • The board can be fitted with a 1.5" waveshare RGB OLED display (not supplied, available from Amazon). This can display readings (see below).
  • The board can be fitted with 6x6 contact switches (not supplied) to work with the display to control temperature.
  • The board normally uses an SCD41 sensor which provides accurate CO₂ readings and temperature and humidity. However this is an expensive component, so the board can be supplied without this, and instead, can be used with a much cheaper DS18B20 sensor via a 3 pin socket. Using a suitable oven it should be possible to fit an SCD41.
  • With open source software it can report readings via MQTT, and can be set up with target temperature profiles over time of day to report to a Daikin controller.
  • Works with Daikin WiFi module to control temperature and report status on display.
  • Can also send MQTT controls for device such as an extraction fan when CO₂ or humidity is too high, and radiator actuator to control heating when too cold.
  • Note that these boards are slightly older, and do not have the on board humidity/temperature sensor which is shown on the current GitHub.


Environmental monitor with display on a bed head


Simple DC powered temperature/humidity monitor

An environmental monitor for humidity, and temperature. This board is intended to be DC powered via connectors, which can daisy chain in and out. Ideally 12V but can work 4V to 40V so could be powered from a USB lead if needed.

£24.00 Order now: Order 1 module 5060634238106

Works with same software as the full Environmental Monitor, so reporting over MQTT and controls for the Faikin air-con, etc.


General boards

There are a number of other ESP32 based boards for general applications, such as LED light strips, GPS, solid state relays, and even a board especially for controlling antique ASR33 teletypes. Most of these do not have any specific software.

These boards are also available cheaply as a bare board for you to build yourself, please contact us for details.


USB-A powered WiFi board

This is a general purpose board for WiFi or Bluetooth operations. It is designed to plug directly in to a standard USB-A port as it is used on a 2mm thick board. It includes a voltage regulator to run the 3.3V ESP32, and an RGB LED.

£24.00 Order now: Order 1 module 5060634238069

IMPORTANT: This is a hobbyist item - no specific firmware supplied.

There is a 5 pin programming/debug set of pads which could be used for 3.3V GPIO if needed (GPIO0, 1 and 3).

This does not have a USB chip, and only uses the USB connector for power.



ESP32 LED driver

A small ESP32 board, designed to be "in-line" with USB-C for power and 3 pin connector t serial LED strips, such as NeoPixel

Available on AmazonPower is from USB, so how many LEDs depends on USB power. Can be powered from 3 pin connector instead if more is needed.

Switches 5V output for LED data line.




ASR33 controller

You may think we are mad doing lunar billing, but this is a ridiculously specific circuit board and we will be delighted if anyone does want this board. It is likely to be made to order individually and we would love to hear your stories of its use.

IMPORTANT: This is a very specialised hobbyist board.

It is designed to work with 20mA current loop interfaces to an antique ASR33 teletype working at 110 Baud. It has an input to allow a button to turn on/off as some ASR33s have extra buttons which can be used for this (even marked "MOTOR START" in some cases). It has outputs to work solid state relays to power the teletype, and separately the motor start (this usually means linking in to the motor supply in the ASR33). The mains switching solid state relays are not included but readily available from Amazon and easy to fit in the base of a teletype.

The open source software allows working of the teletype by MQTT, and also by direct TCP connection. It also includes several interactive functions including punching large text on the paper tape, and a complete copy of the classic Colossal Cave adventure game which can be played locally with no Internet connection.


Example ASR33 usage

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