Components moved June 16th 2026, you'll need a new stencil.

The smallest, most cost-reduced, simplest pipistrelle I can make. It's just 52mm x 57mm in size. There is just a single red LED, so no spectrum display. Apart from that it has a slightly rationalized component list for the analog circuit. It looks like it should be just about £10, maybe £11, with AliExpress Pico clones.

Informal component list, all SMDs are 1206, see DigiKey shopping list for details (https://www.digikey.co.uk/en/mylists/list/0UMMV5D1IZ)

NOTE - the shopping list builds 10, not 5 - adjust numbers of components if you want fewer, but 10 gives you a better price. Also note, if you want to hit the £10 price point, buy Picos fron AliExpress not DigiKey, but make sure you buy RP2040 Pico 1, NOT Pico 2, NOT Pico W. This will save you over £2 per device. You can probably get a much better deal on 3x AAA battery holders as well, shop around.

3x 220R

2x 470R

5x 47k

3x 0.1uF

3x 22uF

1x LED

1x FERRITE

1x mic

1x op-amp

1x AUX / headphone jack

1x Power Switch

1x Pico / AliExpress clone

1x 3AAA battery holder

1x 3D print

And pipnano.uf2 to flash the Picos