Personal Projects

Toby Haynes

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Electronics Projects

This page presents projects I've designed for my own interest and as entrepreneurial possibilities.

My services as a professional electronics designer are available through my consulting company, Phasor Electronics Design.

GPS-Disciplined Frequency Reference

This unit generates an accurate 10 MHz output signal to serve as a reference for other test equipment. It also generates a signal from 1 KHz to 5 MHz, programmable in 1-2-5 steps, and has a comb generator with usable output power above 1.5 GHz. This is useful for calibrating radio receivers. A 10 MHz crystal oven oscillator is divided to 1 Hz and compared with a 1 pulse-per-second input from a GPS receiver. An Atmel AVR microcontroller samples the phase error and digitally implements a PI feedback loop filter to stabilize the crystal oscillator. An LCD shows the internal signal generator settings and the oscillator status. 

GPS Clock

This device displays the date and time, both UTC and local, as well as provides a 1 pulse-per-second output signal accurate to +/- 100 ns. Other functions include signal quality monitoring, position,  altitude, speed, track, and averaging of position and altitude. It incorporates a GPS receiver module, LCD display, and Atmel AVR microcontroller. 

 

1296 MHz Transmit Power Amplifier 


Amplifier (top) and power supply (bottom) in 19-inch rack-mount chassis.

I designed this power amplifier for use on the 23cm band at the VA7MM moonbounce station.  Power output is 500 watts for input drive power of 6 watts. It contains a 6-tube power amplifier cavity unit (OZ9CR design adapted from an earlier military unit) and a surplus 1-tube coaxial driver unit. Tubes are 7289/3CX100A5 planar triodes modified for water cooling. The cooling system is self-contained with a radiator and blower. Internal heater resistors also keep the amplifier from getting too cold is it is used outdoors. Stepper motors are used for mechanical tuning of the driver and power amplifier. An Atmel AVR processor is used for tube current monitoring and automatic detection of faults including over-temperature, over-current, low water level or flow, and water contamination.

The high voltage power supply is a stripped-down surplus AM modulator from a RCAF VHF-band transmitter. It produces 1 amp at 1350V from a 220V line input and is automatically shut down if the amplifier detects a fault.


Remote Control Unit

 The remote control unit also uses an Atmel AVR processor and displays 7 tube cathode currents, power output (506W at lower right), and fault conditions on an LCD. Pushbuttons control the amplifier tuning. An optically-isolated asynchronous serial link connects the remote control unit to the power amplifier.


Transmit / Receive Sequencer

The sequencer uses an Atmel AVR to control the transceiver, power amplifier, receive preamplifer, and transmit/receive relay at the antenna. Switching between transmit and receive takes about 0.2 second, during which all components of the station must be activated in the proper sequence so that the receive preamplifier is not damaged. The sequencer also time-delays the transmitted Morse code signal until transmit mode is ready. In "echo test" mode, the sequencer alternately transmits for 2 seconds to fill the earth-moon-earth path with a signal, then receives for 2 seconds so that the signal can be heard for doppler shift compensation and antenna aiming.

 

Remote Controlled Antenna Switches 

This switch system is used where radios and groups of antennas are separated by long coaxial cables. Switching relay units, at both the antenna and radio sites, share one controller unit located near the radios. One of six antennas is selected at each antenna site. Multiple radios can be switched between multiple coaxial cables at the radio site. A serial data stream from the controller unit activates the relay units. The data link is optically isolated to handle large ground voltage differences between the radio and antenna sites.

 

3-Axis Motor Controller 

These two cards are used in a 3-axis motor controller for a large telescope. PI Control algorithms are used to bring the telescope to the desired position and tracking speed while limiting acceleration A and dA/dt to reduce vibration. A DSP synthesizes the winding current waveforms for stepper motors to achieve smooth rotation at the very low speeds necessary for tracking to rotation of the earth.

The DSP card (left) has a TMS320C32 60MHz floating-point processor, 32K words of RAM, boots from a flash ROM, and has an RS232 serial interface to a PC. Code is written in C. A JTAG port is used for in-circuit debugging of DSP code and programming the flash ROM.

The 3-axis motor driver card (right) has two 12-bit D/A converters and two switch-mode current regulators per axis. Through these, the DSP controls the current in each motor winding. This card uses a PIC microcontroller to interface to a keypad and to accept inputs from optical position encoders.

 

I built this JTAG interface to program and debug the DSP. The ISA card decodes and buffers ISA bus cycles and drives the ribbon cable connected to an external pod. The pod contains a JTAG controller chip and connects through a short cable to the target processor.

 

Scuba Diver Pager 

 

These underwater "pagers" let scuba divers get each other's attention using 200KHz ultrasonic signals. Diving masks block peripheral vision and foam rubber diving hoods block hearing, so divers are without communication if they're beyond arms reach. A microcontroller is used for signal processing to give 8 paging channels and an emergency channel. We developed sealed inductive pushbuttons and a water sensing circuit to turn on the pagers when they are submerged. [Partner: Robert Carlson (concept, mechanical design and fabrication, testing)]

 

Acoustic Pattern Measurement System 

 

These are components of a system used to measure the radiation pattern of an acoustic transducer in water. They include a power supply, ultrasonic transmitter and receiver, stepper motor driver, and an interface to a PC computer. The transmitter generates short ultrasonic pulses and the receiver is time-gated to measure received power of the direct signal and ignore reflections. This allows a radiation pattern to be accurately measured in a small tank. A stepper motor rotates the transducer under test and a PC records the data and plots the radiation pattern. [Partner: Robert Carlson (PC software)]

 

Acoustic Data Transmission Experiments 

 

Two ultrasonic transceivers were assembled for experiments with underwater acoustic data transmission. These include 8051 Microcontrollers, Motorola 56002 DSP's and 200 kHz sonar transmit and receiver. The equipment is splash-proof and stays in boats, while the transducers are lowered under water. Data is transmitted using pulse-position modulation with pulses in a pseudo-random time-hopping pattern to provide multipath immunity. The system also uses time delay to measure distance. Data messages were received through shallow-water at ranges up to 2000 ft. [Partners: Robert Carlson (8051 software, mechanical, field testing), Todd Walker (8051 controller board)]

 

Portable Recording Depth Sounder 

 

This 200 kHz LCD recording depth sounder has a range of 400 feet. It uses a Z80 processor, with software developed in assembly language. A keypad is used to select the range and sounding rate and to store and recall images.

 

Single Sideband Shortwave Radio Transceiver 

 

This is a 14 MHz-band ham radio transceiver. It's a single-conversion superhet that transmits and receives CW and SSB. It has a transmitter power output of 15 watts with fast T/R switching ("full break-in"). My distance record with this is from Vancouver to a ship in the Indian Ocean.

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