Making a GPS Breakout Board by Etching Some Stripboard

I try something I’ve never tried before - etching stripboard/perfboard/veroboard in ferric chloride etchant.

The idea was to create a breakout board for a Quectel L80 GPS module (based on the MediaTek MT3339 chip). This module has a 0.1in (2.54mm) pin pitch, which is rare for recent GPS modules. Most have 2mm or even finer pin spacing. This module’s pin pitch is a good match for common 0.1in stripboard.

I run into all sorts of dramas with cold, weak etchant that over-etched in places while under-etching in others. But a second attempt yielded an acceptable result. All’s well that ends well.

Would I use this technique again? Probably not. But it was an experiment worth trying.

Datasheet for the Quectel L80 GPS module

Making My Arduino Controlled RDA5807M FM Radio

This video shows the assembly of my Arduino controlled RDA5807M based FM radio.

In this video I: - create a break out board for the RRD-102 module containing the RDA5807M. The module has castellated vias at a 2mm pitch. I use some stripboard to break out the connections to 0.1in pitch suitable for breadboarding. - assemble a small logic shifter board. - use hot air to remove a 5V LDO regulator and replace it with a 3.3V regulator. - put all these things together with an Arduino Pro Mini and a PAM8403 amplifier module in order to create an FM radio.

Connecting the RDA5807M FM Radio IC to an Arduino

In this video I connect a really tiny FM radio receiver IC, the RDA5807M to an Arduino. This chip came on a cheap module labelled “RRD-102” from Aliexpress.

I give a demo of the breadboarded circuit receiving a transmission from my now vintage Silicon Chip “Micromitter” low-power FM transmitter.

I’m running the module at 3.3V and the Arduino is running at 5V, so I do some level shifting of the I2C bus to avoid frying the RDA5807M.

The RRD-102 module I purchased for US$0.73 delivered: RRD-102 module.

The logic level shifter board I purchased for US$0.71 delivered: Level Shifter.

Trying Out a PAM8403 Audio Amplifier Module

I try out a cheap amplifier module featuring a PAM8403 chip by hooking it up to some speakers and playing some tunes. This device is a 3W+3W dual channel (stereo) class-D audio amp in a SOIC-16 package.

The Datasheet is available here: PAM8403 Datasheet

Designing a Doorbell Part 4 Pcb Sent to Production

I show the PCB I’ve designed for the wireless doorbell transmitter. I quickly review the schematic, then go on to show the assembly diagram. Lastly, I review the top and bottom copper layers of this two sided board.

The design has been panelized and sent for manufacture by OSH Park. With any luck, I’ll receive the physical boards in 2 to 3 weeks.

Designing a Doorbell Part 2 Demonstrating the Prototype and Talking Thru the Schematic

In this part of a multi-part series, I show off my wireless doorbell transmitter prototype. I then go on to talk about the circuit diagram, pointing out the MSP430G2211 microcontroller (same as in the TI Launchpad), the high-side switch consisting of the FDN340P p-channel MOSFET, the 433.92MHz transmitter module, and lots of other things.

Timelapse of No Knead Bread Dough Rising Made With My Raspberry Pi Camera Rig

I use my recently completed Raspberry Pi camera rig to capture 840 stills of no knead bread dough rising over a 14 hour period. With only a quarter teaspoon of yeast and quite a cold room, the dough rises slowly. The raspistill program was used to capture the stills and the Mac OS X app “Time Lapse Assembler” was used to assemble them into a video.

If you’d like to make your own no knead bread, check out this link