Aircraft Hydraulic System Electrical Tester

Challenge
Produce two identical test systems for checking installation of a jet aircraft hydraulic power system during assembly at the aircraft OEM. Required a hand-held test box with more than a dozen long harnesses to connect to wing and tail power unit electrical interfaces. Used by two technicians, one on the ground and one in the cockpit to completely check the electrical installation. Needs to check and simulate low voltage sensors and verify 3 phase wiring and voltage. All outer surfaces needed to withstand aircraft hydraulic fluid.

Technologies
3-phase 400Hz 115V, isolation amplifiers, precision voltage references, switching power supplies, high-reliability aerospace circular connectors.

Client Results
The design started with discussions and hand sketches of circuits used in past designs, but evolved over the four month project as requirements were uncovered and critical functional and safety aspects were incorporated. New circuits were developed to safely check phase wiring sequence and voltage level for the AC power system. Also developed analog circuits to simulate different types of sensors as well as digital logic to simulate different system states. Two custom anodized aluminum test boxes with their 35′ harness bundles were delivered after verification at DEB Assoc and client test buck. The hardware was accompanied by a full package of mechanical and electrical drawings, test results, PCB fab data, BOM, specifications, and operational instructions.

LED Tail Lamp Demo System

Challenge
Build a demonstration system that can drive all rear exterior lighting for a passenger car using only a three wire interface.

Technologies
SMPS, LIN serial communication, real-time embedded software on Atmel MCU.

Client Results
Client received a finished demo system with stands for the two tail modules and wiring harness to connect tails, CHMSL, battery, and keypad. The system drives 11 addressable LED lamp assemblies from a custom keypad with a LIN serial bus and real-time software. It is used for trade shows and customer demonstrations for their engineering consulting business.

High-Current Automotive Test System

Challenge
Develop a high-quality, robust, rack-mounted test system to be used in an auto supplier development and durability lab for testing 25, 5 amp, solenoid-based smart actuators at a time. The system was used to interface to a National Instruments DAQ with 310 signal lines on 5 D-sub connectors.

Technologies
125A contactor, custom contactor and micro relay drive circuits, active current limiting, current sense, PWM FET drives, custom copper bus bars

Client Results
Client received two identical black, powder-coated, vented aluminum rack-mounted assemblies with chrome pullout handles, silk-screened front panel, push-pull connectors, tri-color status indicator LED light pipes. A full set of interfacing connectors, wiring diagrams, design data, verification test results, and operational description was also included. Although initially the client requested a much less sophisticated design, discussions in the early design phase uncovered how the system was going to be used and some wish-list functions that were able to be realized in the final design. One example was incorporating fast-acting, solid-state current limiting and fault indication. The original design called for internal fuses that would have necessitated disconnecting, pulling, and opening the equipment to replace the fuse. This would have meant major downtime and hassle in an environment where this kind of fault might be expected to occur as a normal part of development. The delivered design simply indicates the fault on the front panel and self-resets when the fault condition is corrected without any danger of over-current damage to either the equipment or DUT.

LED Dome Lamp

Challenge
An auto supplier needed to fix an LED dome light design. It was behind schedule, the switch circuit didn’t work reliably, and the LED was overheating.

Technologies
High output LED, Linear current regulation, CMOS toggle on-off switching

Client Results
The design consisted of two boards, one for the LED, the other for the switch logic and regulation. I was brought in on a Thursday afternoon and introduced to the project. New design files were delivered to the client on the following Monday. These boards were fabricated and tested by the client. The new switching circuit worked perfectly and it could now be run at the full design current due to the improved heat dissipation. The design was deployed to durability vehicles on time.

Automotive USB Media Hub Design

Challenge
The client had several USB Media Hub / Charger designs in process for various auto makers. Each of the designs had EMC, performance, and functional failures that needed to be addressed. Compact packaging and high power density made for a challenging design environment.

Technologies
Buck SMPS, USB, HDMI, Audio amplifiers

Client Results
Each design was optimized in turn at the schematic and board layout level to reduce emissions to within the specified requirements of each auto maker without the addition of expensive CM chokes. Parts count and BOM cost were in most cases reduced compared to the original implementations. We were also able to eliminate the need for EMI shield on one of the designs due to improvements in the RE profile. After successfully addressing EMC issues on existing designs, the client began involving DEB Associates earlier in the design process.

Extender Card Assembly

Challenge
Client needed a mechanical, conductive aluminum frame and PCB assembly to connect high speed data lines between a motherboard and daughter card of an aerospace laser gyro data processing system. The need was to extend the card outside the flight box for test access while maintaining electrical connectivity and signal integrity.

Technologies
10 layer impedance-controlled PCB, 250 pin aerospace-grade connector system, conductive plating of machined aluminum

Client Results
Client received complete mechanical and electrical design data to fabricate the PCB and frame. The design was assembled, tested by the client and successfully deployed at the end customer.

Exhaust After Treatment System Reverse Engineering

Challenge
A client involved in re-manufacturing needed to understand how to diagnose and repair a system used for injecting chemicals into the exhaust stream in heavy duty trucks. This client needed the information to gain credibility and new business as well as enable internal staff to develop test and repair procedures. DEB Assoc was provided with a single field return system for evaluation.

Technologies
Hydraulics, solenoid valves, sensors, embedded control, electric pump.

Client Results
DEB Associates provided hydraulic and electrical schematics and operational description based on disassembly and study of the provided system. Client was able to satisfy his customer and move forward with the business.

Other Projects:

Motor Driver PCB Layout (Automotive Drive Line System)

  • Produced PCB layout artwork for a prototype lube pump driver.
  • H-bridge, CAN, micro-controller

Wire Harness Design (GPS Satellite Test System)

  • Produced drawings for release into Prime’s CAD system. Developed shielding details and BOM for “flight grade” harnesses.

LED Driver PCB for Test System

  • Designed and built PC assys to display logical indication on a test panel.

Dummy Load PCB for GPS Satellite Gyro Unit

  • Designed and built PC assys to simulate loading for Gyro flight unit.
 Automotive HVAC System Reverse Engineering
  • Contracted to reverse engineer pneumatic controls of an automotive HVAC controller and develop a test sequence for automated testing.
 Consulting on Wireless Charging System
  •  Assisted engineers in fixing problems with prototype switching power supply hardware and wireless charging receiver.
460V EMI Filter PCB Design
  • Designed an EMI filter for a high voltage industrial motor controller.
 Design Review of Wireless Office Automation Product
  •  Reviewed existing design for opportunities for cost reduction, EMI issue mitigation. Provided new circuit designs and layout concepts to engineering team.

Automotive Inverter High Voltage Side Layout

  • Implemented new MOSFET driver design on the high voltage side of a 150W automotive inverter.
Wireless Charging System Consulting
  •  Assisted with receiver tuning and prototype construction

High Voltage Fluorescent Ballast Design Analysis

  • Analyze HV DC input ballast design with functional issues
  • Advise client of required resolution
 Heavy duty turbine balance holding fixture mechanical stress certification
  • Analyzed and signed off fixture design for deployment
Automotive Inverter troubleshooting
  • Identified root cause of H-bridge shoot-through at customer’s facility
SMD Chip Replacement on Densely Populated 6-layer board
  • A local embedded systems engineering firm needed to upsize the memory chips on development boards.
  • The memory chips (8-DFN with EP) were pulled and replaced in our lab
Police Light Bar design analysis
  • Reviewed client embedded controller and light engine design to determine steps to meet new function and performance objectives