Shared Projects by Eric

Description: This board is for the “OVM-14 Mk III” Overvoltage Protection Module designed by Robert L. Nuckolls III, as posted to the AeroElectric-List forum. There have been minor changes made to this version, as detailed in the project documentation (see below).

This board provides overvoltage protection for the charging system in an Experimental category aircraft. It’s a “crowbar” type circuit, which is intended to blow a fuse or circuit breaker in the alternator field supply or to open a relay in the AC feed from a permanent magnet stator.

The nominal trip voltages are 16.0V in normal mode and 13.7V in maintenance test mode (both values subject to 1% resistor tolerance). The design is tested and working; see performance on the last page of the documentation PDF.

This project is intended for use in Experimental category aircraft only. Do NOT install it in a CAR Part 3 or FAR Part 23 certificated aircraft without FAA Field Approval.

BOM: Cost is ~$14 for the components to populate this board. Click for a Digi-Key saved list with those parts.

Download: Click here for a .ZIP archive containing full documentation in PDF format, DipTrace v5.1.0.3 CAD files and RS-274X Gerber files.

Interface board for the DS1603NF ultrasonic liquid sensor. Powers the sensor and provides a 20mA constant current 2Hz flashing output for the cathode of an indicator LED. A pushbutton switch in the 12V supply interrupts power, which reboots the sensor and tests the flasher circuit.

Wiring: From the main bus, connect a fused wire to one side of the switch, and to the anode (+, long leg) of the indicator LED. Connect the other switch terminal to the “12V” pad, connect panel ground to the “GND” pad, and connect the cathode (-, short leg) of the indicator LED to the “LED” pad. An LED current-limiting resistor is not needed.

This project is intended for use in Experimental category aircraft only. Do NOT install it in a CAR Part 3 or FAR Part 23 certificated aircraft without FAA Field Approval.

BILL OF MATERIALS:
C1-C3: Vishay K104K15X7RF5TL2 0.1uF 50V X7R Radial Ceramic Capacitor
C4-C5: TDK Corp. FG14X7R1E475KRT06 4.7uF 25V X7R Radial Ceramic Capacitor
D1: Cree, Inc. C503B-RAN-CA0C0AA2 Clear Red LED, 5mm, 2.1V, 20mA, 22,450mcd
J1: JST S4B-XH-A-1(LF)(SN) 4-Position 2.5mm Right Angle Shrouded Header
Q1: Microchip VP2106N3-G 60V 250mA P-Channel MOSFET, TO-92-3
R1-R3: Stackpole RNMF14FTC47K0 47k-Ohm 1/4W 1% Axial Resistor
S1: Pushbutton Switch, Latching Type (Installer’s Choice)
U1: Texas Instruments SE555P Single Timer/Oscillator IC, 8-DIP
U2: Microchip CL520N3-G 20mA Linear LED Driver IC, TO-92-3

Interface board for the DS1603NF ultrasonic liquid sensor. Powers the sensor and provides a 12V output under normal condition and a grounded output under low fuel alarm condition.

Wiring: From the main bus, connect a fused wire to the “12V” pad, connect panel ground to the “GND” pad, connect a momentary pushbutton switch between the “PTT” pad and ground, and connect the “OUT” pad to an EFIS alarm input.

This project is intended for use in Experimental category aircraft only. Do NOT install it in a CAR Part 3 or FAR Part 23 certificated aircraft without FAA Field Approval.

BILL OF MATERIALS:
C1: Vishay K104K15X7RF5TL2 0.1uF 50V X7R Radial Ceramic Capacitor
C2: TDK Corp. FG14X7R1E475KRT06 4.7uF 25V X7R Radial Ceramic Capacitor
J1: JST S4B-XH-A-1(LF)(SN) 4-Position 2.5mm Right Angle Shrouded Header
Q1: Microchip TN2106N3-G 60V 300mA N-Channel MOSFET, TO-92-3
R1-R2: Stackpole RNMF14FTC4K70 4.7k-Ohm 1/4W 1% Axial Resistor
S1: Pushbutton Switch, Normally Open, Momentary Type (Installer’s Choice)

Cost: $4.15 for three.

Description: 10x analog sensor signal differential amplifier. Connect ‘IN+’ and ‘IN-’ to analog voltage signal. Connect ‘BUS’ and ‘GND’ to +11-30V DC supply. Connect ‘OUT’ to desired system input. Board is configured to use ¼" quick-connect tabs, but wires can be soldered directly if desired.

Digi-Key shopping cart here. Populate PCB as indicated on silkscreen.

TESTED / WORKING

Cost: $3.85 for three.

Description: This board is part of a USB programming adapter for the surface-mount (8-SOIC) version of the PICAXE 08M2 microcontroller. It’s basically a cheap replacement for the Revolution Education AXE-027 USB programming cable.

This board includes the standard PICAXE programming circuit consisting of 22k series and 10k pull-down resistors on the Serial In pin, as well as a 0.1uF decoupling capacitor for the PICAXE. The PICAXE is held in a zero insertion force (ZIF) socket (see Bill of Materials, below). Desolder the ZIF socket from its carrier board and resolder it to this board.

The six-pin header on this board connects to a generic FTDI FT232RL USB to RS-232 converter module. Search eBay for “FT232RL Module” and look for the red module with a jumper to select between 3.3V and 5V TTL (set the jumper to 5V). Bend the right-angle header pins on this module so they’re straight up from the board, solder this adapter onto the pins (ZIF socket facing up), then cut the pins flush.

Since many of the FT232RL modules sold on eBay use counterfeit chips, FTDI’s EEPROM programming utility, FT_PROG (here) is not a reliable way to invert the TX and RX lines as required to mimic the AXE-027 cable. Instead of relying on the ability to program the chip’s EEPROM, this board simply uses inverters comprised of two 2N7002 N-channel MOSFETs (the SOT-23-3 footprints on the board).

My Windows 10 computer recognized the serial converter module and loaded drivers automatically, but if you need drivers for an earlier version of Windows, Linux or MacOS, the FTDI Virtual COM Port drivers are available here.

Bill of Materials:

• 1 ea. FT232RL USB to RS-232 converter module (on eBay, here)
• 2 ea. 2N7002 N-channel MOSFET (SOT-23-3)
• 1 ea. 0.1uF ceramic capacitor (0603)
• 2 ea. 1k-ohm resistor (0603)
• 1 ea. 10k-ohm resistor (0603)
• 1 ea. 22k-ohm resistor (0603)
• 1 ea. 8-SOIC ZIF socket (on eBay, here)