Misc Projects

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This is a list of breakout boards and smaller miscellaneous projects that have been created. All of the following designs are open-source, and all are welcome to modify and use these designs as they please.


This is a low quiescent current LDO and Li-Ion single cell charger and protection PCB. It integrates an SY6345 LDO, which supports input voltage range up to 40V, and has 10uA max, 7uA typical quiescent current, with the 2 populated variants of the board set for either 1.5V or 3V operation (to replace single LR44 or similar button cell, or CRxxxx type 3V button cells). The charger is an HX4064 single cell Li-Ion charger IC, with default charging current set for 83.3mA. The board was panelized to a 2x5 panel for a total of 50pcs in the order, and partially assembled with JLCPCB SMT service at a cost of $19.97 including $5.24 shipping. The unassembled components are the SY6345, HX4064, and 0.5 ohm 0805 resistor, with a cost of $0.212/board, for a total per-board cost of $0.611. Long-term testing of this board is ongoing (1.5V variant), showing an estimated ~220 day standby life (to 3.2V battery voltage) with 90mAH Li-Po cell, or an average of 17uA current draw, within the expected max of 20.5uA (2.5uA from voltage divider + 10uA LDO + 2uA from charger + 6uA from protection IC). Another 3V configured board measured at 20.59uA (4.66uA from protection IC) at 4.08V, which also meets expected max of 26uA (8uA from voltage divider + 10uA LDO + 2uA from charger + 6uA from protection IC).

Files: http://www.rev0proto.com/files/MiscProjects/lpldo_panels_v10.zip

4-cell Dummy

This is an attempt to make the cheapest possible 18650 "equipment" as legally defined for air shipment of batteries. It consists of a through-hole 4x 18650 holder, 3 PCBs, a through-hole tactile momentary switch, 1206 white LED, and 1206 62 ohm resistor. Total cost is as follows:

Source Description Link Cost
JLCPCB 10 (x15 per panel / 3 per device) PCBs, combined w/other order (50x) https://jlcpcb.com/ $6.92
LCSC 62 Ohm Resistor (combined w/other order) (100x) https://lcsc.com/en $0.24
Aliexpress 1206 White LED (100x) https://www.aliexpress.com/item/32368682563.html $0.39
Aliexpress Tactile Switch (100x) https://www.aliexpress.com/item/32897610751.html $0.88
Aliexpress 4-cell Holder (50x) https://www.aliexpress.com/item/32817873280.html $44.62
Total For 50x $53.05 ($1.06 per 4 cells, $0.27 per cell)

MS5534 Breakout

This is a breakout board for the MS5534 digital pressure sensor. It includes the sensor itself, a 22uF Tantalum decoupling capacitor, and circuitry to generate a 32kHz reference clock for the chip's ADC and supporting circuitry.

Files: http://www.rev0proto.com/files/MiscProjects/ms5534_v10.zip Clock generation circuit is incorrect, new revision needs to be made.

XBee Pro XSC Breakout

This is a breakout board for the XBee Pro XSC 900MHz radio transceiver. It includes a 300mA 3.3V LDO for powering the device from USB, and all XBee pins are broken out to standard 0.1" headers. The design is similar to the Parallax XBee USB Adapter Board, though specialized for the XBee Pro XSC. Credit goes to Justin Jordan for the original schematic made in PCB Artist.

Files: http://www.rev0proto.com/files/MiscProjects/xbee_usb_breakout_v10.zip

MCP2200 Breakout

This is a breakout board for the MCP2200 USB-to-UART bridge IC. It includes the chip, a mini-B USB connector, and four status LEDs. The IC is provided a 12MHz SMD crystal on the underside of the board, and all pins are accessible on the header.

Files: http://www.rev0proto.com/files/MiscProjects/MCP2200_v11.zip

ADC-10-4 Directional Coupler Breakout

This is a breakout board for the ADC-10-4 directional coupler from Mini-Circuits. It includes the device and SMA connectors for all four ports of the device, as well as pads for soldering on a 50 ohm terminator for the terminated port.

The device's internal construction is of the type detailed on this page: http://michaelgellis.tripod.com/direct.html The schematic for the internal construction is shown below.

Testing was performed on the device using an Anritsu MS4622B vector network analyzer using the configurations shown below. The results are summarized in the two graphs below, which show that the device compares well to and exceeds the manufacturer specifications, with the exception of insertion loss, coupling at higher frequencies, and the CPL port return loss.

Board Files: http://www.rev0proto.com/files/MiscProjects/dircoupler_v10.zip

Test Data: http://www.rev0proto.com/files/MiscProjects/ADC-10-4.zip